fs/dcache: Use read_word_at_a_time() in dentry_string_cmp()
dentry_string_cmp() performs the word-at-a-time reads from 'cs' and may
read slightly more than it was requested in kmallac(). Normally this
would make KASAN to report out-of-bounds access, but this was
workarounded by commit df4c0e36f1b1 ("fs: dcache: manually unpoison
dname after allocation to shut up kasan's reports").
This workaround is not perfect, since it allows out-of-bounds access to
dentry's name for all the code, not just in dentry_string_cmp().
So it would be better to use read_word_at_a_time() instead and revert
commit df4c0e36f1b1.
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/dcache.c b/fs/dcache.c
index 5c7df1d..7fd39f4 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -195,7 +195,7 @@
unsigned long a,b,mask;
for (;;) {
- a = *(unsigned long *)cs;
+ a = read_word_at_a_time(cs);
b = load_unaligned_zeropad(ct);
if (tcount < sizeof(unsigned long))
break;