audio:decode: lack check of av_frame_alloc

[void0red]

TL;DR

we perfom a fuzz on mpv and find this bug.
here lacks a fail alloc check

mpv/audio/decode/ad_lavc.c

Line 106 in f1c9daa

ctx->avframe = av_frame_alloc();

and it will crash at below if avframe is null

mpv/audio/decode/ad_lavc.c

Line 203 in f1c9daa

int ret = avcodec_receive_frame(avctx, priv->avframe);

by the way, I think avctx and avpkt need to be checked too.

Important Information

mpv 1c9daa-dirty Copyright © 2000-2023 mpv/MPlayer/mplayer2 projects
 built on Thu Jun 15 08:49:22 2023
FFmpeg version: 4.4.2-0ubuntu0.22.04.1
FFmpeg library versions:
   libavutil       56.70.100
   libavcodec      58.134.100
   libavformat     58.76.100
   libswscale      5.9.100
   libavfilter     7.110.100
   libswresample   3.9.100

Log file

AddressSanitizer:DEADLYSIGNAL
=================================================================
==3186==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000120 (pc 0x7f55f5dce830 bp 0x619000005f80 sp 0x7ffed7e502f0 T0)
==3186==The signal is caused by a READ memory access.
==3186==Hint: address points to the zero page.
    #0 0x7f55f5dce830  (/lib/x86_64-linux-gnu/libavcodec.so.58+0x27c830) (BuildId: 275d20beefaac834b14cd4f8c8754d59beec5c48)
    #1 0x7f55f5dcf99a in avcodec_receive_frame (/lib/x86_64-linux-gnu/libavcodec.so.58+0x27d99a) (BuildId: 275d20beefaac834b14cd4f8c8754d59beec5c48)
    #2 0x555cac024e89 in receive_frame /root/mpv/build/../audio/decode/ad_lavc.c:203:15
    #3 0x555cac147832 in lavc_process /root/mpv/build/../filters/f_decoder_wrapper.c:1271:20
    #4 0x555cac176249 in mp_filter_graph_run /root/mpv/build/../filters/filter.c:262:13
    #5 0x555cac2ac635 in run_playloop /root/mpv/build/../player/playloop.c:1245:9
    #6 0x555cac28ea29 in play_current_file /root/mpv/build/../player/loadfile.c:1688:9
    #7 0x555cac28ea29 in mp_play_files /root/mpv/build/../player/loadfile.c:1874:13
    #8 0x555cac297d54 in mpv_main /root/mpv/build/../player/main.c:438:9
    #9 0x7f55f4d81d8f  (/lib/x86_64-linux-gnu/libc.so.6+0x29d8f) (BuildId: 69389d485a9793dbe873f0ea2c93e02efaa9aa3d)
    #10 0x7f55f4d81e3f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e3f) (BuildId: 69389d485a9793dbe873f0ea2c93e02efaa9aa3d)
    #11 0x555cabf50914 in _start (/root/mpv/build/mpv+0x150914) (BuildId: 8783f8dbcdeb230f5b3395c900aeb5a2c07e1ed9)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/lib/x86_64-linux-gnu/libavcodec.so.58+0x27c830) (BuildId: 275d20beefaac834b14cd4f8c8754d59beec5c48)
==3186==ABORTING