bcachefs: Fix shift overflow in btree_lost_data()

Kent Overstreet · Kent Overstreet · commit f108ddd467b5 · 2024-05-20T05:37:26.000-04:00
Reported-by: syzbot+29f65db1a5fe427b5c56@syzkaller.appspotmail.com Fixes: 55936af ("bcachefs: Flag btrees with missing data") Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
diff --git a/fs/bcachefs/bcachefs_format.h b/fs/bcachefs/bcachefs_format.h
@@ -1555,6 +1555,12 @@ enum btree_id {
 	BTREE_ID_NR
 };
 
+/*
+ * Maximum number of btrees that we will _ever_ have under the current scheme,
+ * where we refer to them with bitfields
+ */
+#define BTREE_ID_NR_MAX		64
+
 static inline bool btree_id_is_alloc(enum btree_id id)
 {
 	switch (id) {
diff --git a/fs/bcachefs/recovery.c b/fs/bcachefs/recovery.c
@@ -35,6 +35,9 @@
 
 void bch2_btree_lost_data(struct bch_fs *c, enum btree_id btree)
 {
+	if (btree >= BTREE_ID_NR_MAX)
+		return;
+
 	u64 b = BIT_ULL(btree);
 
 	if (!(c->sb.btrees_lost_data & b)) {

Original file line number	Diff line number	Diff line change
`@@ -35,6 +35,9 @@`
`35`	`35`
`36`	`36`	`void bch2_btree_lost_data(struct bch_fs *c, enum btree_id btree)`
`37`	`37`	`{`
	`38`	`+ if (btree >= BTREE_ID_NR_MAX)`
	`39`	`+ return;`
	`40`	`+`
`38`	`41`	`u64 b = BIT_ULL(btree);`
`39`	`42`
`40`	`43`	`if (!(c->sb.btrees_lost_data & b)) {`