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mcc0nnell wants to merge 2 commits into from
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remoteip: avoid pointer underflow on empty header token #756

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7e13160
remoteip: avoid pointer underflow on empty header token
mcc0nnell Sep 14, 2026
a9eb88f
test: keep proxy response tests in numeric order
mcc0nnell Sep 16, 2026
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8 changes: 4 additions & 4 deletions modules/metadata/mod_remoteip.c
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Original file line number Diff line number Diff line change
Expand Up @@ -616,12 +616,12 @@ static int remoteip_modify_request(request_rec *r)
++parse_remote;
}

eos = parse_remote + strlen(parse_remote) - 1;
while (eos >= parse_remote && *eos == ' ') {
*(eos--) = '\0';
eos = parse_remote + strlen(parse_remote);
while (eos > parse_remote && eos[-1] == ' ') {
*--eos = '\0';
}

if (eos < parse_remote) {
if (eos == parse_remote) {
if (remote) {
*(remote + strlen(remote)) = ',';
}
Expand Down
25 changes: 18 additions & 7 deletions test/modules/proxy/test_03_response.py
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Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,7 @@ def _class_scope(self, env):
conf.add([
"RemoteIPHeader X-Forwarded-For",
"RemoteIPTrustedProxy 0.0.0.0",
"RemoteIPTrustedProxy 127.0.0.1",
])
conf.end_vhost()
conf.install()
Expand All @@ -99,13 +100,6 @@ def test_proxy_03_001(self, env):
lognos=["AH01106", "AH10404"]
)

# empty backend response header values are valid
def test_proxy_03_004(self, env):
r = env.curl_get(env.mkurl("http", "test1", "/empty-header"))
assert r.response["status"] == 200
assert "x-empty" in r.response["header"]
assert r.response["body"] == b"Hello"

# checks X-Forwarded headers
def test_proxy_03_002(self, env):
if not env.httpd_is_at_least("2.4.54"):
Expand Down Expand Up @@ -139,3 +133,20 @@ def test_proxy_03_003(self, env):
env.httpd_error_log.ignore_recent(
lognos=["AH00957", "AH00959", "AH01114"]
)

# empty backend response header values are valid
def test_proxy_03_004(self, env):
r = env.curl_get(env.mkurl("http", "test1", "/empty-header"))
assert r.response["status"] == 200
assert "x-empty" in r.response["header"]
assert r.response["body"] == b"Hello"

# a trailing empty RemoteIPHeader token must not underflow the trim pointer
def test_proxy_03_005(self, env):
if not env.has_shared_module("remoteip"):
pytest.skip("need mod_remoteip for this")

r = env.curl_get(env.mkurl("http", "test1", "/forwarded"), options=[
'-H', 'X-Forwarded-For: 192.0.2.1,',
])
assert r.response["status"] == 200