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avcodec/pnm_parser: Remember the size of the image and do not reparse the header 

Fixes: Timeout (11sec -> 60ms)
Fixes: 14270/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PAM_fuzzer-5734809634078720

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2019-04-24 21:14:19 +02:00
parent 938cb783d4
commit 9fc1031ac2
1 changed files with 23 additions and 6 deletions
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29
libavcodec/pnm_parser.c
View File

@ -24,19 +24,35 @@
#include "parser.h" //for ParseContext
#include "pnm.h"
typedef struct PNMParseContext {
ParseContext pc;
int remaining_bytes;
}PNMParseContext;
static int pnm_parse(AVCodecParserContext *s, AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
ParseContext *pc = s->priv_data;
PNMParseContext *pnmpc = s->priv_data;
ParseContext *pc = &pnmpc->pc;
PNMContext pnmctx;
int next;
int next = END_NOT_FOUND;
int skip = 0;
for (; pc->overread > 0; pc->overread--) {
pc->buffer[pc->index++]= pc->buffer[pc->overread_index++];
}
if (pnmpc->remaining_bytes) {
int inc = FFMIN(pnmpc->remaining_bytes, buf_size);
skip += inc;
pnmpc->remaining_bytes -= inc;
if (!pnmpc->remaining_bytes)
next = skip;
goto end;
}
retry:
if (pc->index) {
pnmctx.bytestream_start =
@ -47,7 +63,6 @@ retry:
pnmctx.bytestream = (uint8_t *) buf + skip; /* casts avoid warnings */
pnmctx.bytestream_end = (uint8_t *) buf + buf_size - skip;
}
next = END_NOT_FOUND;
if (ff_pnm_decode_header(avctx, &pnmctx) < 0) {
if (pnmctx.bytestream < pnmctx.bytestream_end) {
if (pc->index) {
@ -79,9 +94,11 @@ retry:
}
if (next != END_NOT_FOUND && pnmctx.bytestream_start != buf + skip)
next -= pc->index;
if (next > buf_size)
if (next > buf_size) {
pnmpc->remaining_bytes = next - buf_size;
next = END_NOT_FOUND;
}
end:
if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
*poutbuf = NULL;
*poutbuf_size = 0;
@ -95,7 +112,7 @@ retry:
AVCodecParser ff_pnm_parser = {
.codec_ids = { AV_CODEC_ID_PGM, AV_CODEC_ID_PGMYUV, AV_CODEC_ID_PPM,
AV_CODEC_ID_PBM, AV_CODEC_ID_PAM },
.priv_data_size = sizeof(ParseContext),
.priv_data_size = sizeof(PNMParseContext),
.parser_parse = pnm_parse,
.parser_close = ff_parse_close,
};