On 26/06/2024 01:57, Michael Niedermayer wrote:
On Wed, Jun 26, 2024 at 01:35:18AM +0200, Lynne via ffmpeg-devel wrote:On 24/06/2024 01:01, Michael Niedermayer wrote:ff_aac_usac_config_decode() needs AACDecContext to be set but some callers pass NULL.I have no real testcase to implement/test this, so failing in this case seems safest. Fixes: member access within null pointer of type 'AACDecContext' (aka 'struct AACDecContext') Fixes: 69435/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AAC_LATM_fuzzer-5733527483121664 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> --- libavcodec/aac/aacdec_usac.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/libavcodec/aac/aacdec_usac.c b/libavcodec/aac/aacdec_usac.c index 132ffee9c20..4856c1786b7 100644 --- a/libavcodec/aac/aacdec_usac.c +++ b/libavcodec/aac/aacdec_usac.c @@ -348,6 +348,9 @@ int ff_aac_usac_config_decode(AACDecContext *ac, AVCodecContext *avctx, int map_pos_set = 0; uint8_t layout_map[MAX_ELEM_ID*4][3] = { 0 }; + if (!ac) + return AVERROR_PATCHWELCOME; + memset(usac, 0, sizeof(*usac)); freq_idx = get_bits(gb, 5); /* usacSamplingFrequencyIndex */This doesn't seem possible at all. There are 2 callers, parse_audio_preroll and decode_audio_specific_config_gb. Both of these will crash way before the function is called. Could you at least get a backtrace?sure libavcodec/aac/aacdec_usac.c:402:39: runtime error: member access within null pointer of type 'AACDecContext' (aka 'struct AACDecContext') SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior libavcodec/aac/aacdec_usac.c:402:39 in AddressSanitizer:DEADLYSIGNAL ================================================================= ==215602==ERROR: AddressSanitizer: SEGV on unknown address 0x000000005b10 (pc 0x00000154771e bp 0x7ffcf5049e90 sp 0x7ffcf5049e70 T0) ==215602==The signal is caused by a READ memory access. #0 0x154771d in av_channel_layout_uninit ffmpeg/libavutil/channel_layout.c:439:25 #1 0x57346e in ff_aac_usac_config_decode ffmpeg/libavcodec/aac/aacdec_usac.c:402:9 #2 0x500a0a in decode_audio_specific_config_gb ffmpeg/libavcodec/aac/aacdec.c:1050:20 #3 0x50a542 in latm_decode_audio_specific_config ffmpeg/libavcodec/aac/aacdec_latm.h:80:21 #4 0x4f8638 in read_stream_mux_config ffmpeg/libavcodec/aac/aacdec_latm.h:160:24 #5 0x4f8638 in read_audio_mux_element ffmpeg/libavcodec/aac/aacdec_latm.h:233 #6 0x4f8638 in latm_decode_frame ffmpeg/libavcodec/aac/aacdec_latm.h:275 #7 0x68f26f in decode_simple_internal ffmpeg/libavcodec/decode.c:429:20 #8 0x68f26f in decode_simple_receive_frame ffmpeg/libavcodec/decode.c:600 #9 0x68f26f in decode_receive_frame_internal ffmpeg/libavcodec/decode.c:631 #10 0x68dc9d in avcodec_send_packet ffmpeg/libavcodec/decode.c:721:15 #11 0x4d1e55 in LLVMFuzzerTestOneInput ffmpeg/tools/target_dec_fuzzer.c:534:25 [...] _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
This patch actually is correct. USAC in LATM is not supported AFAIK. LGTM with a note like:"Happens only when the LATM decoder is used, and USAC is not supported in LATM".
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