> On Apr 11, 2025, at 16:36, Nicolas George <geo...@nsup.org> wrote: > > Zhao Zhili (HE12025-04-11): >> From: Zhao Zhili <zhiliz...@tencent.com> >> >> The macro is meant to suppress false uninitialized warnings. However, >> sometimes these 'false uninitialized warnings' are really undefined >> behavior, and leading to real issue like crash, e.g., ab792634197e. >> >> For false uninitialized warnings, it can be silenced by initialization, >> and compiler can easily optimize away unnecessary initializations. >> >> av_uninit shouldn't be used in any case. > > NAK, you are hiding the UBs, not fixing the bugs.
By the way, logic bug isn’t equal to UB, so I’m not hiding UB. Who put av_uninit in the code means there is no logic bug. If there is, the patchset fixed UB or replaced UB by deterministic logic error, which can’t be worse. > > If the author of the code put av_uninit, that means they believe the > value will always have been initialized by the part of the code > responsible for it. If that is not true, then it is a bug that can lead > to an exploitable security issue or a silent data corruption. If there is no bug for code with av_uninit, the patchset does nothing really. If there is, the patchset fixed or makes the issue deterministic. We don’t initialized all variables when declaration. But if there is a sometimes-uninitialized warning, there is some reason for compiler. Uninitialized warning isn’t the same as deprecated or unused, it should never be ignored in my opinion. > > With your changes, nothing proves that the = 0 you put there is the > right value, the bug is still there: the code expects the value to be > correctly set, but instead there is an arbitrary 0. > > At least, with av_uninit, valgrind and fuzzing can find the bugs. > > Regards, > > -- > Nicolas George > _______________________________________________ > 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". _______________________________________________ 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".
