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avformat/hls: Fix DoS due to infinite loop

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Fixes: loop.m3u

The default max iteration count of 1000 is arbitrary and ideas for a better solution are welcome

Found-by: Xiaohei and Wangchu from Alibaba Security Team

Previous version reviewed-by: Steven Liu <lingjiujianke@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 7ec414892d)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2017-08-26 01:26:58 +02:00
parent 85ffdcd8ff
commit 305f37e5be
2 changed files with 25 additions and 0 deletions
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18
doc/demuxers.texi
View File

@ -300,6 +300,24 @@ used to end the output video at the length of the shortest input file,
which in this case is @file{input.mp4} as the GIF in this example loops
infinitely.
@section hls
HLS demuxer
It accepts the following options:
@table @option
@item live_start_index
segment index to start live streams at (negative values are from the end).
@item allowed_extensions
',' separated list of file extensions that hls is allowed to access.
@item max_reload
Maximum number of times a insufficient list is attempted to be reloaded.
Default value is 1000.
@end table
@section image2
Image file demuxer.

7
libavformat/hls.c
View File

@ -205,6 +205,7 @@ typedef struct HLSContext {
AVDictionary *avio_opts;
int strict_std_compliance;
char *allowed_extensions;
int max_reload;
} HLSContext;
static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
@ -1263,6 +1264,7 @@ static int read_data(void *opaque, uint8_t *buf, int buf_size)
HLSContext *c = v->parent->priv_data;
int ret, i;
int just_opened = 0;
int reload_count = 0;
restart:
if (!v->needed)
@ -1294,6 +1296,9 @@ restart:
reload_interval = default_reload_interval(v);
reload:
reload_count++;
if (reload_count > c->max_reload)
return AVERROR_EOF;
if (!v->finished &&
av_gettime_relative() - v->last_load_time >= reload_interval) {
if ((ret = parse_playlist(c, v->url, v, NULL)) < 0) {
@ -2150,6 +2155,8 @@ static const AVOption hls_options[] = {
OFFSET(allowed_extensions), AV_OPT_TYPE_STRING,
{.str = "3gp,aac,avi,flac,mkv,m3u8,m4a,m4s,m4v,mpg,mov,mp2,mp3,mp4,mpeg,mpegts,ogg,ogv,oga,ts,vob,wav"},
INT_MIN, INT_MAX, FLAGS},
{"max_reload", "Maximum number of times a insufficient list is attempted to be reloaded",
OFFSET(max_reload), AV_OPT_TYPE_INT, {.i64 = 1000}, 0, INT_MAX, FLAGS},
{NULL}
};