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avformat/vividas: Check for input length in get_v() 

Fixes: out of array read
Fixes: 15286/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5658245101780992

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2019-06-27 00:02:31 +02:00
parent 2bbea155bf
commit e69106e70c
1 changed files with 6 additions and 5 deletions
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11
libavformat/vividas.c
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@ -178,12 +178,13 @@ static void decode_block(uint8_t *src, uint8_t *dest, unsigned size,
}
}
static uint32_t get_v(uint8_t *p)
static uint32_t get_v(uint8_t *p, int len)
{
uint32_t v = 0;
const uint8_t *end = p + len;
do {
if (v >= UINT_MAX / 128 - *p)
if (p >= end || v >= UINT_MAX / 128 - *p)
return v;
v <<= 7;
v += *p & 0x7f;
@ -204,7 +205,7 @@ static uint8_t *read_vblock(AVIOContext *src, uint32_t *size,
decode_block(tmp, tmp, 4, key, k2, align);
n = get_v(tmp);
n = get_v(tmp, 4);
if (n < 4)
return NULL;
@ -241,13 +242,13 @@ static uint8_t *read_sb_block(AVIOContext *src, unsigned *size,
k2 = *key;
decode_block(ibuf, sbuf, 8, *key, &k2, 0);
n = get_v(sbuf+2);
n = get_v(sbuf+2, 6);
if (sbuf[0] != 'S' || sbuf[1] != 'B' || (expected_size>0 && n != expected_size)) {
uint32_t tmpkey = recover_key(ibuf, expected_size);
k2 = tmpkey;
decode_block(ibuf, sbuf, 8, tmpkey, &k2, 0);
n = get_v(sbuf+2);
n = get_v(sbuf+2, 6);
if (sbuf[0] != 'S' || sbuf[1] != 'B' || expected_size != n)
return NULL;
*key = tmpkey;