RepoMirrors
/
ffmpeg
mirror of https://git.ffmpeg.org/ffmpeg.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

fftools/ffmpeg_filter: Avoid DynBuf API to improve error checks 

choose_pix_fmts() used the dynamic buffer API to write strings;
as is common among uses of this API, only opening the dynamic buffer
was checked, but not the end result, leading to crashes in case
of allocation failure.
Furthermore, some static strings were duplicated; the allocations
performed here were not properly checked: Allocation failure would
be treated as "could not determine pixel format".
The first issue is fixed by switching to the AVBPrint API which allows
to easily perform checks at the end. Furthermore, the internal buffer
avoids almost all allocations in case the AVBPrint is used.
The AVBPrint also allows to solve the second issue in an elegant way,
because it allows to return the static strings directly.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2021-12-01 17:13:32 +01:00
parent cf8925a096
commit efc323062c
1 changed files with 15 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
fftools/ffmpeg_filter.c
View File

@ -83,7 +83,10 @@ static enum AVPixelFormat choose_pixel_fmt(AVStream *st, AVCodecContext *enc_ctx
return target;
}
static char *choose_pix_fmts(OutputFilter *ofilter)
/* May return NULL (no pixel format found), a static string or a string
* backed by the bprint. Nothing has been written to the AVBPrint in case
* NULL is returned. The AVBPrint provided should be clean. */
static const char *choose_pix_fmts(OutputFilter *ofilter, AVBPrint *bprint)
{
OutputStream *ost = ofilter->ost;
const AVDictionaryEntry *strict_dict = av_dict_get(ost->encoder_opts, "strict", NULL, 0);
@ -96,18 +99,12 @@ static char *choose_pix_fmts(OutputFilter *ofilter)
AVFILTER_AUTO_CONVERT_NONE);
if (ost->enc_ctx->pix_fmt == AV_PIX_FMT_NONE)
return NULL;
return av_strdup(av_get_pix_fmt_name(ost->enc_ctx->pix_fmt));
return av_get_pix_fmt_name(ost->enc_ctx->pix_fmt);
}
if (ost->enc_ctx->pix_fmt != AV_PIX_FMT_NONE) {
return av_strdup(av_get_pix_fmt_name(choose_pixel_fmt(ost->st, ost->enc_ctx, ost->enc, ost->enc_ctx->pix_fmt)));
return av_get_pix_fmt_name(choose_pixel_fmt(ost->st, ost->enc_ctx, ost->enc, ost->enc_ctx->pix_fmt));
} else if (ost->enc && ost->enc->pix_fmts) {
const enum AVPixelFormat *p;
AVIOContext *s = NULL;
uint8_t *ret;
int len;
if (avio_open_dyn_buf(&s) < 0)
exit_program(1);
p = ost->enc->pix_fmts;
if (ost->enc_ctx->strict_std_compliance > FF_COMPLIANCE_UNOFFICIAL) {
@ -116,11 +113,11 @@ static char *choose_pix_fmts(OutputFilter *ofilter)
for (; *p != AV_PIX_FMT_NONE; p++) {
const char *name = av_get_pix_fmt_name(*p);
avio_printf(s, "%s|", name);
av_bprintf(bprint, "%s%c", name, p[1] == AV_PIX_FMT_NONE ? '\0' : '|');
}
len = avio_close_dyn_buf(s, &ret);
ret[len - 1] = 0;
return ret;
if (!av_bprint_is_complete(bprint))
exit_program(1);
return bprint->str;
} else
return NULL;
}
@ -416,12 +413,13 @@ static int insert_filter(AVFilterContext **last_filter, int *pad_idx,
static int configure_output_video_filter(FilterGraph *fg, OutputFilter *ofilter, AVFilterInOut *out)
{
char *pix_fmts;
OutputStream *ost = ofilter->ost;
OutputFile *of = output_files[ost->file_index];
AVFilterContext *last_filter = out->filter_ctx;
AVBPrint bprint;
int pad_idx = out->pad_idx;
int ret;
const char *pix_fmts;
char name[255];
snprintf(name, sizeof(name), "out_%d_%d", ost->file_index, ost->index);
@ -457,13 +455,14 @@ static int configure_output_video_filter(FilterGraph *fg, OutputFilter *ofilter,
pad_idx = 0;
}
if ((pix_fmts = choose_pix_fmts(ofilter))) {
av_bprint_init(&bprint, 0, AV_BPRINT_SIZE_UNLIMITED);
if ((pix_fmts = choose_pix_fmts(ofilter, &bprint))) {
AVFilterContext *filter;
ret = avfilter_graph_create_filter(&filter,
avfilter_get_by_name("format"),
"format", pix_fmts, NULL, fg->graph);
av_freep(&pix_fmts);
av_bprint_finalize(&bprint, NULL);
if (ret < 0)
return ret;
if ((ret = avfilter_link(last_filter, pad_idx, filter, 0)) < 0)