Revision 447ac906e189535e77dcb1f4bbe3f1bc917d4c12 authored by Patrick Steinhardt on 01 December 2022, 14:45:31 UTC, committed by Junio C Hamano on 05 December 2022, 06:14:16 UTC
The `struct attr_stack` tracks the stack of all patterns together with their attributes. When parsing a gitattributes file that has more than 2^31 such patterns though we may trigger multiple out-of-bounds reads on 64 bit platforms. This is because while the `num_matches` variable is an unsigned integer, we always use a signed integer to iterate over them. I have not been able to reproduce this issue due to memory constraints on my systems. But despite the out-of-bounds reads, the worst thing that can seemingly happen is to call free(3P) with a garbage pointer when calling `attr_stack_free()`. Fix this bug by using unsigned integers to iterate over the array. While this makes the iteration somewhat awkward when iterating in reverse, it is at least better than knowingly running into an out-of-bounds read. While at it, convert the call to `ALLOC_GROW` to use `ALLOC_GROW_BY` instead. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 34ace8b
base85.c
#include "cache.h"
#undef DEBUG_85
#ifdef DEBUG_85
#define say(a) fprintf(stderr, a)
#define say1(a,b) fprintf(stderr, a, b)
#define say2(a,b,c) fprintf(stderr, a, b, c)
#else
#define say(a) do { /* nothing */ } while (0)
#define say1(a,b) do { /* nothing */ } while (0)
#define say2(a,b,c) do { /* nothing */ } while (0)
#endif
static const char en85[] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
'U', 'V', 'W', 'X', 'Y', 'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
'u', 'v', 'w', 'x', 'y', 'z',
'!', '#', '$', '%', '&', '(', ')', '*', '+', '-',
';', '<', '=', '>', '?', '@', '^', '_', '`', '{',
'|', '}', '~'
};
static char de85[256];
static void prep_base85(void)
{
int i;
if (de85['Z'])
return;
for (i = 0; i < ARRAY_SIZE(en85); i++) {
int ch = en85[i];
de85[ch] = i + 1;
}
}
int decode_85(char *dst, const char *buffer, int len)
{
prep_base85();
say2("decode 85 <%.*s>", len / 4 * 5, buffer);
while (len) {
unsigned acc = 0;
int de, cnt = 4;
unsigned char ch;
do {
ch = *buffer++;
de = de85[ch];
if (--de < 0)
return error("invalid base85 alphabet %c", ch);
acc = acc * 85 + de;
} while (--cnt);
ch = *buffer++;
de = de85[ch];
if (--de < 0)
return error("invalid base85 alphabet %c", ch);
/* Detect overflow. */
if (0xffffffff / 85 < acc ||
0xffffffff - de < (acc *= 85))
return error("invalid base85 sequence %.5s", buffer-5);
acc += de;
say1(" %08x", acc);
cnt = (len < 4) ? len : 4;
len -= cnt;
do {
acc = (acc << 8) | (acc >> 24);
*dst++ = acc;
} while (--cnt);
}
say("\n");
return 0;
}
void encode_85(char *buf, const unsigned char *data, int bytes)
{
say("encode 85");
while (bytes) {
unsigned acc = 0;
int cnt;
for (cnt = 24; cnt >= 0; cnt -= 8) {
unsigned ch = *data++;
acc |= ch << cnt;
if (--bytes == 0)
break;
}
say1(" %08x", acc);
for (cnt = 4; cnt >= 0; cnt--) {
int val = acc % 85;
acc /= 85;
buf[cnt] = en85[val];
}
buf += 5;
}
say("\n");
*buf = 0;
}
#ifdef DEBUG_85
int main(int ac, char **av)
{
char buf[1024];
if (!strcmp(av[1], "-e")) {
int len = strlen(av[2]);
encode_85(buf, av[2], len);
if (len <= 26) len = len + 'A' - 1;
else len = len + 'a' - 26 - 1;
printf("encoded: %c%s\n", len, buf);
return 0;
}
if (!strcmp(av[1], "-d")) {
int len = *av[2];
if ('A' <= len && len <= 'Z') len = len - 'A' + 1;
else len = len - 'a' + 26 + 1;
decode_85(buf, av[2]+1, len);
printf("decoded: %.*s\n", len, buf);
return 0;
}
if (!strcmp(av[1], "-t")) {
char t[4] = { -1,-1,-1,-1 };
encode_85(buf, t, 4);
printf("encoded: D%s\n", buf);
return 0;
}
}
#endif
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