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avutil/imgutils: Optimize memset_bytes() by using av_memcpy_backptr() 

This is strongly based on code by Marton Balint, and depends on the previous commit

Fixes: Timeout
Fixes: 11502/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WCMV_fuzzer-5664893810769920
Before: Executed clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WCMV_fuzzer-5664893810769920 in 11209 ms
After:  Executed clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WCMV_fuzzer-5664893810769920 in  4104 ms

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Marton Balint <cus@passwd.hu>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit f64c0dffa1)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2018-12-25 23:15:20 +01:00
parent 63de02051d
commit f5c6d42124
1 changed files with 5 additions and 22 deletions
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27
libavutil/imgutils.c
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@ -501,7 +501,6 @@ int av_image_copy_to_buffer(uint8_t *dst, int dst_size,
static void memset_bytes(uint8_t *dst, size_t dst_size, uint8_t *clear,
size_t clear_size)
{
size_t pos = 0;
int same = 1;
int i;
@ -521,28 +520,12 @@ static void memset_bytes(uint8_t *dst, size_t dst_size, uint8_t *clear,
if (clear_size == 1) {
memset(dst, clear[0], dst_size);
dst_size = 0;
} else if (clear_size == 2) {
uint16_t val = AV_RN16(clear);
for (; dst_size >= 2; dst_size -= 2) {
AV_WN16(dst, val);
dst += 2;
}
} else if (clear_size == 4) {
uint32_t val = AV_RN32(clear);
for (; dst_size >= 4; dst_size -= 4) {
AV_WN32(dst, val);
dst += 4;
}
} else if (clear_size == 8) {
uint32_t val = AV_RN64(clear);
for (; dst_size >= 8; dst_size -= 8) {
AV_WN64(dst, val);
dst += 8;
}
} else {
if (clear_size > dst_size)
clear_size = dst_size;
memcpy(dst, clear, clear_size);
av_memcpy_backptr(dst + clear_size, clear_size, dst_size - clear_size);
}
for (; dst_size; dst_size--)
*dst++ = clear[pos++ % clear_size];
}
// Maximum size in bytes of a plane element (usually a pixel, or multiple pixels