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ffmpeg/libavcodec/pnm.c
Michael Niedermayer 68f30567df avcodec/pnm: skip reading trailing bytes in get_pnm() 
None of the keys we support is that long and other keys
lead to decoder failure. None of the values is expected
to be longer, they are all numbers or short keywords.

This simplifies the code

Fixes: Timeout (9sec->43ms)
Fixes: 15177/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PAM_fuzzer-5080556716425216

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
2019-08-23 22:26:50 +02:00

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/*
* PNM image format
* Copyright (c) 2002, 2003 Fabrice Bellard
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdlib.h>
#include <string.h>
#include "libavutil/avassert.h"
#include "libavutil/imgutils.h"
#include "avcodec.h"
#include "internal.h"
#include "pnm.h"
static inline int pnm_space(int c)
{
return c == ' ' || c == '\n' || c == '\r' || c == '\t';
}
static void pnm_get(PNMContext *sc, char *str, int buf_size)
{
char *s;
int c;
uint8_t *bs = sc->bytestream;
const uint8_t *end = sc->bytestream_end;
/* skip spaces and comments */
while (bs < end) {
c = *bs++;
if (c == '#') {
while (c != '\n' && bs < end) {
c = *bs++;
}
} else if (!pnm_space(c)) {
break;
}
}
s = str;
while (bs < end && !pnm_space(c) && (s - str) < buf_size - 1) {
*s++ = c;
c = *bs++;
}
*s = '\0';
sc->bytestream = bs;
}
int ff_pnm_decode_header(AVCodecContext *avctx, PNMContext * const s)
{
char buf1[32], tuple_type[32];
int h, w, depth, maxval;
int ret;
if (s->bytestream_end - s->bytestream < 3 ||
s->bytestream[0] != 'P' ||
s->bytestream[1] < '1' ||
s->bytestream[1] > '7') {
s->bytestream += s->bytestream_end > s->bytestream;
s->bytestream += s->bytestream_end > s->bytestream;
return AVERROR_INVALIDDATA;
}
pnm_get(s, buf1, sizeof(buf1));
s->type= buf1[1]-'0';
if (s->type==1 || s->type==4) {
avctx->pix_fmt = AV_PIX_FMT_MONOWHITE;
} else if (s->type==2 || s->type==5) {
if (avctx->codec_id == AV_CODEC_ID_PGMYUV)
avctx->pix_fmt = AV_PIX_FMT_YUV420P;
else
avctx->pix_fmt = AV_PIX_FMT_GRAY8;
} else if (s->type==3 || s->type==6) {
avctx->pix_fmt = AV_PIX_FMT_RGB24;
} else if (s->type==7) {
w = -1;
h = -1;
maxval = -1;
depth = -1;
tuple_type[0] = '\0';
for (;;) {
pnm_get(s, buf1, sizeof(buf1));
if (!strcmp(buf1, "WIDTH")) {
pnm_get(s, buf1, sizeof(buf1));
w = strtol(buf1, NULL, 10);
} else if (!strcmp(buf1, "HEIGHT")) {
pnm_get(s, buf1, sizeof(buf1));
h = strtol(buf1, NULL, 10);
} else if (!strcmp(buf1, "DEPTH")) {
pnm_get(s, buf1, sizeof(buf1));
depth = strtol(buf1, NULL, 10);
} else if (!strcmp(buf1, "MAXVAL")) {
pnm_get(s, buf1, sizeof(buf1));
maxval = strtol(buf1, NULL, 10);
} else if (!strcmp(buf1, "TUPLTYPE") ||
/* libavcodec used to write invalid files */
!strcmp(buf1, "TUPLETYPE")) {
pnm_get(s, tuple_type, sizeof(tuple_type));
} else if (!strcmp(buf1, "ENDHDR")) {
break;
} else {
return AVERROR_INVALIDDATA;
}
}
/* check that all tags are present */
if (w <= 0 || h <= 0 || maxval <= 0 || maxval > UINT16_MAX || depth <= 0 || tuple_type[0] == '\0' ||
av_image_check_size(w, h, 0, avctx) || s->bytestream >= s->bytestream_end)
return AVERROR_INVALIDDATA;
ret = ff_set_dimensions(avctx, w, h);
if (ret < 0)
return ret;
s->maxval = maxval;
if (depth == 1) {
if (maxval == 1) {
avctx->pix_fmt = AV_PIX_FMT_MONOBLACK;
} else if (maxval < 256) {
avctx->pix_fmt = AV_PIX_FMT_GRAY8;
} else {
avctx->pix_fmt = AV_PIX_FMT_GRAY16;
}
} else if (depth == 2) {
if (maxval < 256) {
avctx->pix_fmt = AV_PIX_FMT_GRAY8A;
} else {
avctx->pix_fmt = AV_PIX_FMT_YA16;
}
} else if (depth == 3) {
if (maxval < 256) {
avctx->pix_fmt = AV_PIX_FMT_RGB24;
} else {
avctx->pix_fmt = AV_PIX_FMT_RGB48;
}
} else if (depth == 4) {
if (maxval < 256) {
avctx->pix_fmt = AV_PIX_FMT_RGBA;
} else {
avctx->pix_fmt = AV_PIX_FMT_RGBA64;
}
} else {
return AVERROR_INVALIDDATA;
}
return 0;
} else {
av_assert0(0);
}
pnm_get(s, buf1, sizeof(buf1));
w = atoi(buf1);
pnm_get(s, buf1, sizeof(buf1));
h = atoi(buf1);
if(w <= 0 || h <= 0 || av_image_check_size(w, h, 0, avctx) || s->bytestream >= s->bytestream_end)
return AVERROR_INVALIDDATA;
ret = ff_set_dimensions(avctx, w, h);
if (ret < 0)
return ret;
if (avctx->pix_fmt != AV_PIX_FMT_MONOWHITE && avctx->pix_fmt != AV_PIX_FMT_MONOBLACK) {
pnm_get(s, buf1, sizeof(buf1));
s->maxval = atoi(buf1);
if (s->maxval <= 0 || s->maxval > UINT16_MAX) {
av_log(avctx, AV_LOG_ERROR, "Invalid maxval: %d\n", s->maxval);
s->maxval = 255;
}
if (s->maxval >= 256) {
if (avctx->pix_fmt == AV_PIX_FMT_GRAY8) {
avctx->pix_fmt = AV_PIX_FMT_GRAY16;
} else if (avctx->pix_fmt == AV_PIX_FMT_RGB24) {
avctx->pix_fmt = AV_PIX_FMT_RGB48;
} else if (avctx->pix_fmt == AV_PIX_FMT_YUV420P && s->maxval < 65536) {
if (s->maxval < 512)
avctx->pix_fmt = AV_PIX_FMT_YUV420P9;
else if (s->maxval < 1024)
avctx->pix_fmt = AV_PIX_FMT_YUV420P10;
else
avctx->pix_fmt = AV_PIX_FMT_YUV420P16;
} else {
av_log(avctx, AV_LOG_ERROR, "Unsupported pixel format\n");
avctx->pix_fmt = AV_PIX_FMT_NONE;
return AVERROR_INVALIDDATA;
}
}
}else
s->maxval=1;
/* more check if YUV420 */
if (av_pix_fmt_desc_get(avctx->pix_fmt)->flags & AV_PIX_FMT_FLAG_PLANAR) {
if ((avctx->width & 1) != 0)
return AVERROR_INVALIDDATA;
h = (avctx->height * 2);
if ((h % 3) != 0)
return AVERROR_INVALIDDATA;
h /= 3;
avctx->height = h;
}
return 0;
}
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