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[BUG] ebtree: string_equal_bits() could return garbage on identical strings

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(from ebtree 6.0.2)

When inserting duplicates on x86/x86_64, the assembler optimization
does not support equal strings that both end up with a zero, and
can return garbage in the bit number, possibly causing a segfault
for its users. The only case where this can happen appears to be
in ebst_insert().
(cherry picked from commit 006152c62ae56d151188626e6074a79be3928858)
This commit is contained in:
Willy Tarreau 2010-09-28 11:28:19 +02:00
parent a56235c5d3
commit a97e73a0a1
1 changed files with 3 additions and 3 deletions
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6
ebtree/ebtree.h
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@ -793,7 +793,8 @@ static forceinline int check_bits(const unsigned char *a,
* may be rechecked. It is only passed here as a hint to speed up the check. * may be rechecked. It is only passed here as a hint to speed up the check.
* The caller is responsible for not passing an <ignore> value larger than any * The caller is responsible for not passing an <ignore> value larger than any
* of the two strings. However, referencing any bit from the trailing zero is * of the two strings. However, referencing any bit from the trailing zero is
* permitted. * permitted. Equal strings are reported as equal up to and including the last
* zero.
*/ */
static forceinline int string_equal_bits(const unsigned char *a, static forceinline int string_equal_bits(const unsigned char *a,
const unsigned char *b, const unsigned char *b,
@ -818,9 +819,8 @@ static forceinline int string_equal_bits(const unsigned char *a,
if (c) if (c)
break; break;
if (!d) if (!d)
break; return (beg << 3) + 8; /* equal bytes + zero */
} }
/* OK now we know that a and b differ at byte <beg>, or that both are zero. /* OK now we know that a and b differ at byte <beg>, or that both are zero.
* We have to find what bit is differing and report it as the number of * We have to find what bit is differing and report it as the number of
* identical bits. Note that low bit numbers are assigned to high positions * identical bits. Note that low bit numbers are assigned to high positions