Commit b6776488 authored Jan 20, 2021 by George Burgess IV

mp4: fix potential dereferences of NULL

clang's static analyzer wasn't happy about the potential load of NULL
from mLastTrack on line (after this patch) 4606:

> frameworks/av/media/extractors/mp4/MPEG4Extractor.cpp:4663:32:
warning: Access to field 'meta' results in a dereference of a null
pointer (loaded from field 'mLastTrack')
[clang-analyzer-core.NullDereference]

Since there's a NULL check above, the analyzer assumes `mLastTrack` may be
NULL here. This doesn't seem like an unreasonable assumption to me.

While I'm in the area, looks like we may have the same issue with MP3,
so I've opportunistically added a NULL check there.

Bug: None
Test: TreeHugger
Change-Id: I1e1be8bdb36fd059e1f4eabc165650389d02e45e

parent e392f2cf

media/extractors/mp4/MPEG4Extractor.cpp

+7 −0

Original line number	Diff line number	Diff line
		@@ -4505,6 +4505,9 @@ status_t MPEG4Extractor::updateAudioTrackInfoFromESDS_MPEG4Audio(

		if (objectTypeIndication == 0x6B \|\| objectTypeIndication == 0x69) {
		// mp3 audio
		if (mLastTrack == NULL)
		return ERROR_MALFORMED;

		AMediaFormat_setString(mLastTrack->meta,AMEDIAFORMAT_KEY_MIME, MEDIA_MIMETYPE_AUDIO_MPEG);
		return OK;
		}
		@@ -4595,6 +4598,10 @@ status_t MPEG4Extractor::updateAudioTrackInfoFromESDS_MPEG4Audio(
		if (offset >= csd_size \|\| csd[offset] != 0x01) {
		return ERROR_MALFORMED;
		}

		if (mLastTrack == NULL) {
		return ERROR_MALFORMED;
		}
		// formerly kKeyVorbisInfo
		AMediaFormat_setBuffer(mLastTrack->meta,
		AMEDIAFORMAT_KEY_CSD_0, &csd[offset], len1);