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* src/hash.c (jhash_string): Don't read past end of string.

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Original patch from Dmitry Goncharov <dgoncharov@users.sf.net>.
This commit is contained in:
Paul Smith 2019-10-05 11:23:31 -04:00
parent a4a173928f
commit bd7d03f8cd
1 changed files with 45 additions and 30 deletions
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75
src/hash.c
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@ -16,6 +16,7 @@ this program. If not, see <http://www.gnu.org/licenses/>. */
#include "makeint.h"
#include "hash.h"
#include <assert.h>
#define CALLOC(t, n) ((t *) xcalloc (sizeof (t) * (n)))
#define MALLOC(t, n) ((t *) xmalloc (sizeof (t) * (n)))
@ -364,7 +365,8 @@ round_up_2 (unsigned long n)
r += val; \
} while(0);
unsigned jhash(unsigned const char *k, int length)
unsigned int
jhash(unsigned const char *k, int length)
{
unsigned int a, b, c;
@ -408,12 +410,16 @@ unsigned jhash(unsigned const char *k, int length)
return c;
}
#define UINTSZ sizeof (unsigned int)
#ifdef WORDS_BIGENDIAN
/* The ifs are ordered from the first byte in memory to the last. */
#define sum_up_to_nul(r, p, flag) \
#define sum_up_to_nul(r, p, plen, flag) \
do { \
unsigned int val; \
memcpy(&val, (p), 4); \
unsigned int val = 0; \
size_t pn = (plen); \
size_t n = pn < UINTSZ ? pn : UINTSZ; \
memcpy (&val, (p), n); \
if ((val & 0xFF000000) == 0) \
flag = 1; \
else if ((val & 0xFF0000) == 0) \
@ -427,51 +433,60 @@ unsigned jhash(unsigned const char *k, int length)
/* First detect the presence of zeroes. If there is none, we can
sum the 4 bytes directly. Otherwise, the ifs are ordered as in the
big endian case, from the first byte in memory to the last. */
#define sum_up_to_nul(r, p, flag) \
do { \
unsigned int val; \
unsigned int zeroes; \
memcpy(&val, (p), 4); \
zeroes = ((val - 0x01010101) & ~val); \
if (!(zeroes & 0x80808080)) \
r += val; \
else if ((val & 0xFF) == 0) \
flag = 1; \
else if ((val & 0xFF00) == 0) \
r += val & 0xFF, flag = 1; \
else if ((val & 0xFF0000) == 0) \
r += val & 0xFFFF, flag = 1; \
else \
r += val, flag = 1; \
#define sum_up_to_nul(r, p, plen, flag) \
do { \
unsigned int val = 0; \
size_t pn = (plen); \
size_t n = pn < UINTSZ ? pn : UINTSZ; \
memcpy (&val, (p), n); \
flag = ((val - 0x01010101) & ~val) & 0x80808080; \
if (!flag) \
r += val; \
else if (val & 0xFF) \
{ \
if ((val & 0xFF00) == 0) \
r += val & 0xFF; \
else if ((val & 0xFF0000) == 0) \
r += val & 0xFFFF; \
else \
r += val; \
} \
} while (0)
#endif
/* This function performs magic which is correct but causes ASAN heartburn
when we pass in a global constant string (at least). */
__attribute__((no_sanitize_address))
unsigned jhash_string(unsigned const char *k)
unsigned int
jhash_string(unsigned const char *k)
{
unsigned int a, b, c;
unsigned int have_nul = 0;
unsigned const char *start = k;
size_t klen = strlen ((const char*)k);
/* Set up the internal state */
a = b = c = JHASH_INITVAL;
/* All but the last block: affect some 32 bits of (a,b,c) */
for (;;) {
sum_up_to_nul(a, k, have_nul);
sum_up_to_nul(a, k, klen, have_nul);
if (have_nul)
break;
k += 4;
sum_up_to_nul(b, k, have_nul);
k += UINTSZ;
assert (klen >= UINTSZ);
klen -= UINTSZ;
sum_up_to_nul(b, k, klen, have_nul);
if (have_nul)
break;
k += 4;
sum_up_to_nul(c, k, have_nul);
k += UINTSZ;
assert (klen >= UINTSZ);
klen -= UINTSZ;
sum_up_to_nul(c, k, klen, have_nul);
if (have_nul)
break;
k += 4;
k += UINTSZ;
assert (klen >= UINTSZ);
klen -= UINTSZ;
jhash_mix(a, b, c);
}