Commit bfe7aa6c authored Feb 01, 2018 by Andrey Ryabinin Committed by Linus Torvalds Feb 01, 2018

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 df4c0e36 ("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 df4c0e36.

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 1a3241ff

fs/dcache.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -195,7 +195,7 @@ static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char
		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;

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