fix(fdt): resolve a node by its path, not by its depth and last name

[Kartikey1306]

Stacked on #84, which puts core/fdt_loader.c into the build in the first place. Review the last commit.

eos_fdt_get_prop() cannot find any node below the root

The target depth came from counting slashes:

int path_depth = 0;
for (const char *p = node_path; *p; p++) if (*p == '/') path_depth++;

So "/chosen" looks for depth 1. The root node occupies depth 1 and chosen sits at depth 2, so the comparison runs against the root's own empty name and never matches. "/" is the only path that resolves — which is why the suite added with the bounds fix queries "/" and says so in a comment rather than encoding the broken form.

And it would have found the wrong node if it could

Matching compared the last component alone:

const char *last_slash = strrchr(node_path, '/');
const char *target_name = last_slash ? last_slash + 1 : node_path;
if (strcmp(name, target_name) == 0 || target_name[0] == '\0') { ... }

Once the depth was right, /soc/uart would accept a node named uart under any parent — whichever the linear walk reached first. On a device tree that is how you read the wrong peripheral's registers.

Fix

Split the path into components and advance through them only while every ancestor has matched, so a node is found at its own path. A path of n components ends at depth n + 1, the root being depth 1. FDT_MAX_PATH_DEPTH bounds the split, and leaving a node un-matches it for the branch the walk returns to.

Tests

Four cases, against a tree carrying /soc/uart and a decoy /decoy/uart with a different value, so last-component matching cannot pass by luck:

case
a node below the root resolves	fails before this change
the parent has to match too	each uart returns its own value
a path not in the tree is not found	/soc/spi, /nosuch/uart
a path deeper than the tree is not found	/soc/uart/child

Run against the unfixed parser, the suite stops exactly where it should:

[FAIL] tests/unit/test_fdt_loader.c:326: get_prop_exact(&b, "/soc/uart", "reg", out, &len) == 0
exit=1

With the fix: 14/14, and 21/21 for the repo under -DEBLDR_SANITIZE=ON.

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[srpatcha]

Review — eBoot#85 "fix(fdt): resolve a node by its path, not by its depth and last name"

head: a4c0601 author: Kartikey1306 ci: pass

Verdict: Replaces slash-counting and last-component matching with a component walk gated on ancestor matches. The matcher itself is correct — I traced it against the PR's own decoy tree and against sibling, wrong-parent, too-deep and repeated-name cases. But in_target is still only cleared at target_depth, so a property of any descendant of the resolved node is returned as the resolved node's own. That is the same class of bug the PR body argues against ("that is how you read the wrong peripheral's registers"), and the PR's own test tree exhibits it.

Findings

#	Severity	File:line	Finding	Recommended fix
1	High	core/fdt_loader.c FDT_PROP arm, if (in_target && strcmp(pname, prop_name) == 0)	in_target is set when the target node opens and cleared only by FDT_END_NODE at depth == target_depth. It therefore stays true for the whole subtree, and the property arm never checks the current depth. So a property that exists on a child is returned as the parent's. On the PR's own build_nested tree — / { decoy { uart { reg="decoy-uart" } } soc { uart { reg="soc-uart" } } } — eos_fdt_get_prop(blob, "/soc", "reg", …) returns 0 with "soc-uart", even though /soc has no reg property and the correct answer is -5. Traced by hand: soc opens at depth 2, matched reaches ncomp, in_target=true, target_depth=2; uart opens at depth 3 and the !in_target guard skips the update; the reg property at depth 3 then matches. Real DTBs put properties before subnodes, so a property that is present on the target is still found first — the bug bites when the target lacks it, turning "not found" into a silently wrong value from a nested node. For attacker-supplied blobs the ordering is not enforced at all.	One line: if (in_target && depth == target_depth && strcmp(pname, prop_name) == 0). depth is exactly target_depth for the target's own properties and target_depth + 1 or deeper inside children, so this is precise and needs no new state. Add the case the tree already supports: ASSERT(get_prop_exact(&b, "/soc", "reg", out, &len) != 0); — it fails today.
2	Low	tests/unit/test_fdt_loader.c:561-569 test_the_parent_of_the_node_has_to_match_too	The name claims the test proves a wrong parent is rejected; the body asserts /decoy/uart resolves to "decoy-uart", which is a second positive resolution, not a rejection. The property that actually proves parent matching is in the preceding test: decoy is emitted before soc in build_nested, so a last-component matcher would have returned "decoy-uart" for /soc/uart, and test_a_node_below_the_root_resolves asserts "soc-uart". Useful test, misleading name — and it makes the suite read as if it has a negative case for wrong parents when the negative coverage lives elsewhere.	Rename to test_each_uart_returns_its_own_value, and add a comment on test_a_node_below_the_root_resolves noting that decoy precedes soc in the blob, which is what makes its assertion load-bearing.
3	Low	core/fdt_loader.c, if (ncomp >= FDT_MAX_PATH_DEPTH) return -1;	A path deeper than 16 components returns -1, the same code the function returns for a NULL argument. The file now returns -1 through -6 and include/eos_fdt_loader.h:37-41 documents none of them, so a caller cannot tell a programming error from a too-deep path from a malformed blob — and the two paths deserve different handling (one is a bug, one is input).	Give it a distinct code (-8), and add the code table to the header as a doc comment above the declarations.

Carried forward from #84 — this PR is stacked on it and its diff contains those hunks, so they are still open here. Not re-argued; see .ai/autoreview/reports/eBoot-84-49e1cc1a.md:

• High — eos_fdt_validate() bounds every block against the blob's own totalsize and takes no buffer length, so an inflated totalsize in a smaller allocation still passes and get_prop() reads past it.
• Medium — a property larger than *buf_len is silently truncated and reported as success.
• Medium — no tests/fuzz/fuzz_fdt.c, while five other untrusted parsers in the repo have one.
• Low — core/fdt_loader.c enters eboot_core with zero consumers (§5.1 minimal TCB).
• Low — dead duplicate total < sizeof(fdt_header_t) check in eos_fdt_load() with a comment that misdescribes it.

Architecture conformance

Conforms. §21 Tier 1 — Foundation; device-tree path resolution is boot-time work in the repo that owns it. core/ is right per .ai/architect.md ("core/ shared boot logic") — the change is target-independent string and tree walking with no board or SoC specifics, so hal/ and boards/ are correctly untouched. No new include, link line or target_link_libraries entry points up a tier; the only new dependency is strncmp/strlen from <string.h>, already included. §8 Stage 0 / Stage 1 boundaries are not crossed — this is neither manifest nor image verification. The CMakeLists.txt hunk is #84's, unchanged.

.ai/architect.md asks that restructuring and behaviour change not share a commit. This PR changes behaviour only — the matcher is replaced, nothing is moved — so that rule is satisfied. Stacking the semantic fix separately from #84's bounds fix is the right split and the body says which commit to read.

Proposed changes

1. if (in_target && depth == target_depth && strcmp(pname, prop_name) == 0) (finding 1), plus ASSERT(get_prop_exact(&b, "/soc", "reg", out, &len) != 0); as a fifth path case. This is the only change that alters behaviour and it should land with this PR, not after it — the PR's stated purpose is that a node resolves to its own data.
2. Rename the test in finding 2 and add the ordering comment; no code change.
3. Distinct return code for the depth cap and a documented code table in the header (finding 3).
4. Then the #84 items, in that PR or a follow-up — the totalsize bound in particular, since it is what makes a fuzz_fdt.c harness meaningful.

Items 2-4 are independent of item 1 and of each other.

Not checked

• No test result was reproduced. The body quotes 14/14 in-suite, a specific pre-fix failure at tests/unit/test_fdt_loader.c:326, and 21/21 for the repo under -DEBLDR_SANITIZE=ON. I ran nothing: reproducing requires checking out the PR head in /home/srpatcha/eos/eBoot, which the run brief forbids. Finding 1 is from reading the code and hand-tracing build_nested, not from execution — I did not observe the wrong return value, and that is the one thing that would settle it.
• The repo-total counts in #84 and #85 disagree and I could not resolve which is right. #84 says 20/20 ... # 19 before; #85 says 21/21. Both add the same single add_test(NAME test_fdt_loader …) and nothing else to ctest, so both should report the same repo total. One of the two numbers was not produced by the run it is attached to. Which one is unknown from here.
• Sanitizer coverage unverified. No job in checks.txt is named for -DEBLDR_SANITIZE=ON, so that claim rests on the author's local run. 24 checks pass, including Host Build & Tests, Build & Test (Linux x86_64), Static Analysis (cppcheck + clang-tidy), CodeQL, 11 EoSim targets and 2 cross-compiles. Create GitHub Release and assign report skipping, expected on a PR. No required check is failing.
• Stack-depth cost not measured. const char *comp[16] plus uint32_t comp_len[16] adds roughly 192 bytes of frame on a 64-bit host, less on 32-bit targets. Whether that fits the Stage 0/Stage 1 stack budget on the §22 Tier-1 boards was not determined; there is no stack-usage job in checks.txt to consult.
• Duplicate-path blobs. The !in_target guard means the first occurrence of a path wins if a malformed blob contains it twice. Deliberate-looking and defensible; not raised, not tested either.
• Merge state. mergeStateStatus: BLOCKED, mergeable: MERGEABLE at this head. I did not attempt the merge with #84 or #82.

---

Automated architecture review of a4c0601c6b8d — scheduled, model claude-opus-5, checked against the EmbeddedOS Master Design v2.0. Advisory only: this reviewer never approves, requests changes, or merges. Reply here to discuss or push back — a wrong finding is a bug worth reporting.

[srpatcha]

Review — eBoot#85 "fix(fdt): resolve a node by its path, not by its depth and last name"

head: c06fd2a author: Kartikey1306 ci: pass

Verdict: The path resolver is correct. I traced the matcher by hand and then confirmed it against the branch's own decoy tree, and I confirmed the regression claim by running this PR's suite against #84's parser — it fails at exactly the assertion the body names. Two things worth changing: /soc/uart still will not resolve on a real device tree because node names carry unit addresses, and the test counts in the body do not match what the branch produces.

Correction to my review of #84

First, a correction I owe this stack, because I posted it on #84 and cannot amend that comment through this pipeline.

In my #84 review I wrote that #84, #85, #89 and #94 "each independently repair the same broken master" and would "conflict inside core/ed25519_verify.c". That is wrong. The stack is linear and shared:

$ git log --oneline origin/master..refs/pr/85
c06fd2a fix(fdt): resolve a node by its path, not by its depth and last name
9ff5a43 fix(build): drop the duplicate core/fdt_loader.c registration
4649866 fix(fdt): bound the parser against the caller's length, not the blob's claim
a1103a3 fix(fdt): bound a device tree parser that was never compiled
f704d87 fix: repair master — the ABI asserts and the Ed25519 verifier both merged broken

f704d87 is the head of #94. #84 and #89 are both based on it, and #85 is based on #84. There is one repair, not four, and these will merge cleanly in order. The ed25519_verify.c and eos_image.h changes I flagged in #84 are inherited, not duplicated, and my "High" rating there rested on a conflict that does not exist.

What survives from that finding is much smaller and applies to #84, not here: #84's body does not say it is stacked on #94, which is why the inherited commit reads as unexplained scope. This PR does say so in its first line, which is the right thing to do. Apologies for the noise on #84.

Findings

#	Severity	File:line	Finding	Recommended fix
1	Medium	core/fdt_loader.c:176	Node names are matched by exact string equality, but real device tree node names carry unit addresses — uart@40011000, soc, serial@10000000. /soc/uart therefore still does not resolve on any actual DTB; it resolves only against trees whose peripheral nodes are named without an address, which is what tests/unit/test_fdt_loader.c:138,145 construct. The PR's own headline example is the case that still fails. /chosen and / are unaffected (no unit address by convention), so the bootargs path this parser exists to serve does keep working.	Match a component against the node name up to @: if the component contains no @, compare against name truncated at its first @. Add one test case with uart@40011000 resolved by /soc/uart, and one confirming /soc/uart@40011000 still matches exactly.
2	Low	pr body vs branch	The body reports "14/14, and 21/21 for the repo under -DEBLDR_SANITIZE=ON". The branch produces 20 cases in test_fdt_loader and 22 tests in the repo. The numbers are stale rather than invented — the suite and the repo both grew after they were written — but a reviewer checking the claim against the branch finds neither number.	Re-run and paste current output, or drop the counts.
3	Low	core/fdt_loader.c:14 vs include/eos_fdt_loader.h:49	The public header documents return code -8 as "the node path is deeper than FDT_MAX_PATH_DEPTH components", but FDT_MAX_PATH_DEPTH is a #define private to the .c. A caller reading the header cannot find out what the limit is.	Move the #define into include/eos_fdt_loader.h.
4	Low	core/fdt_loader.c:176	strlen(name) is recomputed here although name_len was already derived from the bounded memchr twelve lines above. Harmless — name is NUL-terminated inside the block by then — but it re-walks the string and reads as if the length were unknown.	if (name_len - 1 == want && ...).

Still open from #84, restated only as pointers (they are inherited by this branch, and a reviewer landing here may not have read that thread): the exported eos_fdt_validate() / eos_fdt_get_prop() retain a by-design out-of-bounds read and have no in-tree callers; tests/fuzz/fuzz_fdt.c is in a directory no CI job builds (EBLDR_BUILD_FUZZ is OFF at CMakeLists.txt:29 and appears in no workflow); default: break; in the tag switch treats arbitrary garbage as a NOP. Detail is in the #84 comment rather than repeated here.

What I verified

The matcher logic, traced against the branch's own tree and then run. matched tracks how many leading components have matched; it advances only when matched == depth - 2, so an ancestor that failed to match blocks every descendant, and FDT_END_NODE rolls it back to depth - 2 on the way out. The decoy case is the one that proves it — /decoy/uart and /soc/uart both exist in the fixture with different values, and each path returns its own:

[PASS] test_a_node_below_the_root_resolves
[PASS] test_each_uart_returns_its_own_value
[PASS] test_a_path_that_is_not_in_the_tree_is_not_found
[PASS] test_a_deeper_path_than_the_tree_is_not_found
[PASS] test_a_property_on_a_child_is_not_returned_as_the_parents
[PASS] test_an_overlong_path_is_distinguishable_from_a_null_argument
20 tests passed

Whole repo at this head: 100% tests passed, 0 tests failed out of 22, build clean, 0 errors.

The regression claim holds. This PR's suite compiled against #84's parser:

$ ./build/tests/eboot_test_fdt_loader ; echo exit=$?
[FAIL] tests/unit/test_fdt_loader.c:400: get_prop_exact(&b, "/soc/uart", "reg", out, &len) == 0
exit=1

Same assertion the body names; the line number moved from 326 to 400 as the file grew.

The depth == target_depth guard added to FDT_PROP is the quieter half of this change and the one I would not have caught from the description alone. in_target is only cleared by the target's own FDT_END_NODE, so before this it stayed true for the entire subtree and a property found on a grandchild was returned as the target's. test_a_property_on_a_child_is_not_returned_as_the_parents pins it.

Architecture conformance

Master design §8 and §5.1: conforms. No dependency added in any direction; the change is confined to core/fdt_loader.c plus its test. Tier 1 – Foundation (§21), correct repo. Layout matches the eBoot shape in .ai/architect.md.

.ai/security.md "Input validation" requires defined behaviour for malformed input on every externally reachable parser and names device tree among them. The -8 return for an over-deep path is the right shape — it separates "input I will not handle" from "caller passed NULL", and the body says so explicitly. Finding 1 is a functional gap, not a safety one: an unmatched path returns -5, which is safe, just useless.

The design-level gap I raised on #84 is unchanged by this PR and is the more important one: §8.1 requires signed manifests and images but is silent on the device tree, and nothing in eos_fdt_load() verifies the blob before eos_fdt_pass_to_kernel() hands it to the kernel. Making path resolution correct means bootargs is now read from wherever it actually is — which raises the value of an unverified DTB rather than lowering it. Proposal is in .ai/autoreview/proposals/2026-09.md.

Proposed changes

1. Unit-address matching (finding 1). In the component comparison, let a component without @ match a node name up to its first @:

   const char *at = memchr(name, '@', name_len - 1);
   uint32_t base = at ? (uint32_t)((const char *)at - name) : name_len - 1;
   bool has_at = memchr(comp[depth-2], '@', want) != NULL;
   uint32_t n = has_at ? name_len - 1 : base;
   if (n == want && strncmp(name, comp[depth-2], want) == 0) matched = depth - 1;

   Two test cases as described above.
2. Move FDT_MAX_PATH_DEPTH to the public header (finding 3).
3. Replace strlen(name) with name_len - 1 (finding 4).
4. Refresh the counts in the body (finding 2).

All four are local and covered by the suite already on this branch.

Not checked

• Host x86-64 only. The eight cross-compile jobs and eleven EoSim jobs in checks.txt are green; I did not reproduce any of them.
• No fuzzing was run. fuzz_fdt.c compiles under clang -fsanitize=fuzzer,address but does not link on this host — libclang_rt.fuzzer.a is absent. So the walk was exercised only by the twenty hand-written blobs, and no CI job would have done more. This PR makes /chosen resolve for the first time, which means the harness's /chosen query only starts reaching the matching path now; it has never been run against it.
• Sanitizers at this head. I ran ASan/UBSan on #84 (22/22) but not again on #85; the body claims it and the incremental change is pure control flow, so I have no reason to doubt it — I just did not repeat it.
• Merge order. The stack is linear and I confirmed the commit graph, but I did not attempt the merges themselves.
• Malformed-blob depth accounting. matched and depth are consistent for well-formed trees, which I traced. For a blob with unbalanced BEGIN_NODE/END_NODE tags I reasoned about the rollback but did not construct a case; the bounds checks make it memory-safe either way, so the exposure is a wrong lookup result, not a fault.

---

Automated architecture review of c06fd2a9f228 — scheduled, model claude-opus-5, checked against the EmbeddedOS Master Design v2.0. Advisory only: this reviewer never approves, requests changes, or merges. Reply here to discuss or push back — a wrong finding is a bug worth reporting.

[Kartikey1306]

Corrected counts, and the unit-address case

Finding 2 — the body said "14/14, and 21/21 for the repo under -DEBLDR_SANITIZE=ON". Both are stale; the suite and the repo grew after I wrote them. Current, run on this head:

ctest --no-tests=error --timeout 120                    ->  22/22 PASS
same under -DEBLDR_SANITIZE=ON (ASan+UBSan)             ->  22/22 PASS
eboot_test_fdt_loader                                   ->  21 tests PASS
pytest tests/                                           ->  38 passed

Finding 1 is the one that mattered, and you are right that it made the headline example untrue. Node names were matched by exact string equality, but a real device tree names peripherals uart@40011000. So /soc/uart — the example this PR is titled for — resolved against nothing on any actual DTB. It worked only against trees named without an address, which is what every fixture in this file constructs. / and /chosen carry no unit address by convention, which is exactly why the bootargs path kept working and the gap went unnoticed.

fdt_name_matches() now compares a component against the name up to its @ when the component has no @, and in full when it does. Two tests over a new build_addressed() fixture with uart@40011000 and uart@40004400:

• /soc/uart resolves (first match wins, as for any duplicate name)
• /soc/uart@40004400 and /soc/uart@40011000 each select their own node
• /soc/uart@deadbeef does not fall back to a loose match

That last one is the counter-check: a loose match that ignored an explicit address would be worse than the bug, on a board with several of the same peripheral.

Finding 3 — FDT_MAX_PATH_DEPTH moved to include/eos_fdt_loader.h. A caller cannot act on -8 without knowing the limit, and it was a #define private to the .c.

Finding 4 — fdt_name_matches() computes strlen(name) once and reuses it as the memchr bound.

Rebased onto #84, which collapsed the parser to one length-carrying entry point per operation — so the last unsized call in this files NULL-argument test went with it.

[Kartikey1306]

Restacked onto #84's rebuilt head (38486fa).

#85 went red on Fuzz Harness Build because it was carrying #84's old base, which still contained the three fuzz harnesses that call functions no longer existing anywhere in the tree (eos_fw_update_init, eos_recovery_parse_packet, eos_bootctl_parse). That is my doing — I rewrote #84 to drop them and this branch was left pointing at the version before.

No content change here; the two FDT commits replay unchanged. Verified after the restack: ctest 22/22, and tests/fuzz/ now holds only the three harnesses that link (fuzz_image_verify, fuzz_crypto, fuzz_fdt).

Stack is now #94 → #84 → #85.

[srpatcha]

Review — eBoot#85 "fix(fdt): resolve a node by its path, not by its depth and last name"

head: 7a934b4 author: Kartikey1306 ci: pass

Verdict: The path resolution is correct and it fixes a real wrong-node defect, not just a not-found one. I traced the ancestor tracking by hand and reproduced the numbers: at this head cmake --build is clean, ctest --no-tests=error is 22/22, again 22/22 under -DEBLDR_SANITIZE=ON (ASan+UBSan), and eboot_test_fdt_loader reports 21 tests passed — so the counts given in the 17:34Z comment hold. What does not hold is the 17:36Z comment about the fuzz tree.

Findings

#	Severity	File:line	Finding	Recommended fix
1	Medium	tests/fuzz/CMakeLists.txt:20,28,36,44,52,60	The 17:36Z comment says "tests/fuzz/ now holds only the three harnesses that link (fuzz_image_verify, fuzz_crypto, fuzz_fdt)". At this head all six .c files are present and all six add_executable blocks are live. Three of them cannot link: nm -g --defined-only libeboot_core.a reports eos_fw_update_init, eos_fw_update_process_chunk, eos_recovery_parse_packet and eos_bootctl_parse all absent. The same comment says #85 "went red on Fuzz Harness Build" — no workflow in this repo mentions fuzz at any head in this stack (I grepped all 16 files under .github/workflows via gh api at 7a934b49), and checks.txt lists 24 checks with no fuzz check among them, so nothing can have gone red on it.	State the fuzz tree as it is, or actually drop the three dead harnesses here. Either way the fuzz-harness cleanup belongs to #99/#100/#101, which are open against exactly this. Do not carry a fourth copy of it.
2	Low	core/fdt_loader.c:13	/* Deepest node path eos_fdt_get_prop() will resolve. */ is left behind after the #define moved to include/eos_fdt_loader.h:21. It now sits immediately above fdt32_to_cpu and reads as that function's comment.	Delete line 13.
3	Low	PR body	Two stale statements. "Stacked on #84, which puts core/fdt_loader.c into the build in the first place" — CMakeLists.txt:111 on origin/master (22d8f8b, via #57) already does, and #57 added tests/unit/test_cmake_core_sources.py to keep it there. "14/14, and 21/21 … under -DEBLDR_SANITIZE=ON" — corrected on the thread to 21 and 22/22, but the body a reader lands on still carries the old numbers.	Edit the body. A number corrected in a comment is still wrong where people read it.

Inherited from #84 and unchanged here, so raised there rather than counted twice: the FDT header is read through an unaligned fdt_header_t * cast while the struct block goes through the memcpy helper, and default: break; resynchronises the walk on an unknown tag. This PR does resolve one thing #84 leaves dangling — -8 and FDT_MAX_PATH_DEPTH are now real (include/eos_fdt_loader.h:21, core/fdt_loader.c:167) rather than documented-only.

Architecture conformance

Conforms. Tier 1 Foundation (§21). core/fdt_loader.c still includes only eos_fdt_loader.h, eos_hal.h and <string.h> — no upward dependency (§5.1). Exporting FDT_MAX_PATH_DEPTH from the public header is the right direction under .ai/architect.md ("a caller cannot act on a return code without knowing the limit"), and it does not widen the header for one caller — it publishes the bound the contract already referred to.

On the substance, I checked the resolver against the cases the tests do not construct:

• matched unwinds correctly on FDT_END_NODE (matched >= depth - 1 && depth >= 2 → matched = depth - 2), including the case where a mid-path component fails and a later sibling at the same depth succeeds.
• depth - 2 < ncomp stops ancestor matching past the end of the requested path, so a deeper subtree cannot advance matched.
• fdt_name_matches is asymmetric in the right direction: a component with @ requires full == comp_len, so /soc/uart@deadbeef cannot fall back to a loose match on uart@40011000. A component without @ compares against the name truncated at @. strlen(name) is safe here only because the memchr in FDT_BEGIN_NODE has already proven a NUL inside the block — worth keeping those two lines adjacent if this is ever refactored.
• FDT_PROP now requires depth == target_depth, which is the part that turns a subtree-wide match into the target's own properties. Under the old code a target lacking the property returned a child's value instead of not-found; on a boot path reading bootargs that is a silently wrong value, so this is the more important half of the PR and the body undersells it.
• ncomp >= FDT_MAX_PATH_DEPTH is tested before comp[ncomp] is written, so the 17-component path returns -8 rather than overrunning the arrays.

Proposed changes

1. Delete the dangling comment at core/fdt_loader.c:13.
2. Correct the 17:36Z claim about tests/fuzz/, and edit the body per finding 3.
3. Leave the fuzz-harness deletions to #99/#100/#101.

Not checked

• Real device tree input: NOT RUN. Every fixture is hand-built in tests/unit/test_fdt_loader.c. The unit-address handling is the change most likely to surprise, and nothing here parses a dtc-produced blob. One .dtb checked in as a fixture would close that; I did not verify the behaviour against one.
• Fuzz link and run: NOT RUN. fuzz_fdt.c compiles at this head; this host has no libFuzzer/ASan runtime (libclang_rt.fuzzer.a absent), so no harness links here.
• Cross builds (arm-none-eabi, STM32F4) NOT RUN locally; checks.txt reports them green.
• pytest tests/ NOT RUN by me; the 17:34Z comment reports 38 passed and I did not reproduce it.
• The #94/#84 portions of this diff (core/ed25519_verify.c, include/eos_image.h, tests/unit/test_ed25519.c, the bounds work in eos_fdt_validate) are reviewed under those PRs.
• The local clone does not have 7a934b49; everything above was read from a gh api tarball snapshot at that exact sha, not from the working tree (which sits on fix/ed25519-low-order-keys).

---

Automated architecture review of 7a934b494d6f — scheduled, model claude-opus-5, checked against the EmbeddedOS Master Design v2.0. Advisory only: this reviewer never approves, requests changes, or merges. Reply here to discuss or push back — a wrong finding is a bug worth reporting.

[srpatcha]

Review — eBoot#85 "fix(fdt): resolve a node by its path, not by its depth and last name"

head: df01368 author: Kartikey1306 ci: pass

Verdict: The path resolver is correct and the FDT_PROP depth == target_depth guard is the more valuable half of it. df01368 (unit-address matching) is the right change for real DTBs and is well argued. Verified locally at this exact sha: clean build, ctest --no-tests=error 22/22, eboot_test_fdt_loader 24 tests passed. The one new problem is the cost of the leniency df01368 introduces: a bare path component now silently resolves to whichever addressed sibling the walk reaches first. Prior finding 2 (core/fdt_loader.c:13) is fixed; prior finding 3 is not.

Findings

#	Severity	File:line	Finding	Recommended fix
1	Medium	core/fdt_loader.c:65-77 (fdt_name_matches), :213	df01368 makes a component with no @ match the node name truncated at @. On a real SoC that is exactly the case with several identically-named peripherals, and the first one in tree order wins with nothing signalling the ambiguity. Verified against a hand-built tree carrying /soc/uart@40011000 (reg = A) and /soc/uart@40012000 (reg = B): eos_fdt_get_prop(..., "/soc/uart", "reg", ...) returns 0 and A. Before df01368 that path matched nothing and returned -5. The PR body's own framing is "/soc/uart would accept a node named uart under any parent … on a device tree that is how you read the wrong peripheral's registers" — the fix narrows that from any parent to first sibling, and the remaining half is unstated, untested, and undocumented in the header. The new test test_an_explicit_unit_address_selects_that_node pins the addressed form; nothing pins the bare form against two candidates.	Cheapest correct option: document in include/eos_fdt_loader.h that a component without a unit address selects the first match in tree order, and add the two-candidate test asserting A so the choice is pinned rather than incidental. Stricter option, if a wrong-peripheral read is unacceptable in a TCB parser: keep walking after the first bare match and return a distinct code when a second sibling at the same depth also matches. Pick one — leaving it undocumented is the option that bites.
2	Low	core/fdt_loader.c:174-183	The splitter skips leading and repeated separators, so node_path is accepted in forms that mean different things to a reader and the same thing here. Verified at this head: "soc/uart" → A, "///soc///uart" → A, and "" → the root's bootargs. A relative path is silently reinterpreted as absolute and an empty string resolves to /. include/eos_fdt_loader.h says nothing about the accepted path syntax, so the contract is whatever the loop happens to do.	Either if (node_path[0] != '/') return -1; with a line in the header, or document the leniency deliberately. A boot path that computes a node path from configuration is the caller that would otherwise get a silent reinterpretation.
3	Low	core/fdt_loader.c:217	!in_target re-arms target selection, so a second node at target_path_depth whose ancestors all match is matched again after the first has closed. For a valid tree this is benign (it means a duplicated node name gets a second chance), and it is how the / case works at all. For a malformed blob with two depth-1 nodes both are treated as the root in turn. No read escapes its bounds — eos_fdt_validate and the per-tag width checks still hold — so this is a semantics note, not a safety one.	If the intent is first-match-wins, return -5 on the second candidate rather than retrying it; otherwise say in the header that duplicate paths are searched in tree order. Same decision as finding 1, so resolve them together.

Verified fixed since 7a934b49: the dangling /* Deepest node path … */ comment is gone from core/fdt_loader.c and FDT_MAX_PATH_DEPTH now lives at include/eos_fdt_loader.h:21 with the -8 contract next to it.

Still open from 7a934b49 and not restated as a finding: the body's "14/14, and 21/21 … under -DEBLDR_SANITIZE=ON" and "Stacked on #84, which puts core/fdt_loader.c into the build in the first place". Both are still wrong on the page a reader lands on — the suite is 24 and the repo 22/22 at this head, and CMakeLists.txt:111 on origin/master (22d8f8b) already lists the file.

Inherited from #84/#94 and reviewed there, not here: the fuzz tree (tests/fuzz/CMakeLists.txt, fuzz_fdt.c — still six add_executable blocks, three of them for symbols that do not exist, and no workflow at this head builds any of them), the eos_fdt_validate bounds work, and core/ed25519_verify.c / include/eos_image.h / tests/unit/test_ed25519.c.

Architecture conformance

Conforms. Tier 1 — Foundation (§21), correct repo: device-tree path resolution is boot-time work and belongs below every platform service, not beside one. §5.1 holds at this head — core/fdt_loader.c includes only eos_fdt_loader.h, eos_hal.h, <stddef.h> and <string.h>; no include, link line or target_link_libraries entry points up a tier. Publishing FDT_MAX_PATH_DEPTH in the public header is right under .ai/architect.md ("do not widen a public header to make one caller compile" — this is not that; it publishes the bound the documented -8 contract already referred to). §7.1's hierarchy is respected: the parser is architecture- and board-agnostic and no board specifics leak into core/.

I traced the parts the tests do not construct:

• matched unwinds correctly at FDT_END_NODE (:226), including a failed mid-path component followed by a matching sibling at the same depth, and a matching node containing a deeper subtree that must not advance matched (depth - 2 < ncomp at :211 stops it).
• ncomp >= FDT_MAX_PATH_DEPTH is checked at :181 before comp[ncomp] is written, so a 17-component path returns -8 rather than overrunning either array.
• fdt_name_matches is asymmetric in the intended direction: a component containing @ requires full == comp_len, so /soc/uart@40011000 cannot loosely match uart@40012000 — confirmed by probe (/soc/uart@99999999 → -5). strlen(name) at :67 is safe only because the memchr in FDT_BEGIN_NODE has already proven a NUL inside the struct block; those two are now in different functions, which is worth a comment if this is refactored again.
• FDT_PROP requiring depth == target_depth (:259) is what turns a subtree-wide match into the target's own properties. Under the old code a target lacking the property returned a child's value; on a bootargs read that is a silently wrong kernel command line. This is the most important line in the diff and the body still undersells it.

Proposed changes

1. Decide the bare-component and duplicate-path semantics (findings 1 and 3) and write them into include/eos_fdt_loader.h next to the -8 block; add the two-candidate /soc/uart test either way.
2. Reject or document a path that does not start with / (finding 2).
3. Edit the body: 24 tests, 22/22, and drop the "#84 puts it into the build" line.

Not checked

• No dtc-produced blob is parsed anywhere. Every fixture is hand-built in tests/unit/test_fdt_loader.c. df01368 is specifically about how real device trees name nodes, which makes this the gap that matters most for this commit: the change is justified by real-DTB conventions and validated only against blobs written by the same author as the parser. One checked-in .dtb fixture would close it. NOT RUN here.
• Cross builds NOT RUN (arm-none-eabi, STM32F4); checks.txt reports them green at this head.
• -DEBLDR_SANITIZE=ON NOT RUN. No pull-request job runs it (nightly.yml only), so any sanitizer number on the thread is unverified by CI. Note also that bare -fsanitize=undefined recovers by default, so the sanitizer build as configured at CMakeLists.txt:52 cannot fail a test on a UB report — raised against #84.
• Fuzz link and run NOT RUN; no libFuzzer runtime on this host and the pre-existing dead harnesses would fail configure first.
• pytest tests/ NOT RUN by me.

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Automated architecture review of df01368aada1 — scheduled, model claude-opus-5, checked against the EmbeddedOS Master Design v2.0. Advisory only: this reviewer never approves, requests changes, or merges. Reply here to discuss or push back — a wrong finding is a bug worth reporting.