[PATCH 3/3] assoc_array: trim the final shortcut word when skip_to_level is chunk-aligned
Michael Bommarito <[email protected]>
| Newsgroups | gmane.linux.kernel,gmane.linux.kernel.lsm |
|---|---|
| Message-ID | <[email protected]> |
assoc_array_walk() masks off the bits past shortcut->skip_to_level in
the final word of a shortcut before testing it, gated on
round_up(sc_level, chunk_size) > skip_to_level. Once sc_level is
word-aligned (every word after the first) round_up() is a no-op and the
guard never fires for the word that contains skip_to_level, so its stale
high bits leak into the dissimilarity word and can steer the walk down
the wrong descendant.
Test sc_level + ASSOC_ARRAY_KEY_CHUNK_SIZE > skip_to_level directly; an
exact-multiple skip_to_level ends on the boundary and stays untrimmed.
Fixes: 3cb989501c26 ("Add a generic associative array implementation.")
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Michael Bommarito <[email protected]>
---
lib/assoc_array.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/assoc_array.c b/lib/assoc_array.c
index bcc6e0a013eb8..1de2c337f8fcf 100644
--- a/lib/assoc_array.c
+++ b/lib/assoc_array.c
@@ -255,7 +255,7 @@ assoc_array_walk(const struct assoc_array *array,
sc_segments = shortcut->index_key[sc_level >> ASSOC_ARRAY_KEY_CHUNK_SHIFT];
dissimilarity = segments ^ sc_segments;
- if (round_up(sc_level, ASSOC_ARRAY_KEY_CHUNK_SIZE) > shortcut->skip_to_level) {
+ if (sc_level + ASSOC_ARRAY_KEY_CHUNK_SIZE > shortcut->skip_to_level) {
/* Trim segments that are beyond the shortcut */
int shift = shortcut->skip_to_level & ASSOC_ARRAY_KEY_CHUNK_MASK;
dissimilarity &= ~(ULONG_MAX << shift);
--
2.53.0