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authorMartin Storsjö <martin@martin.st>2021-10-18 12:31:38 +0300
committerMartin Storsjö <martin@martin.st>2021-10-18 14:34:30 +0300
commitab792634197e364ca1bb194f9abe36836e42f12d (patch)
tree8e3c793852db8d197e90cb0b4552517e7a297183 /libavcodec/avdct.h
parentfd3bd5c492834bd100bb2462d1e1dc25a66f28f8 (diff)
downloadffmpeg-ab792634197e364ca1bb194f9abe36836e42f12d.tar.gz
seek: Fix crashes in ff_seek_frame_binary if built with latest Clang 14
Passing an uninitialized variable as argument to a function is undefined behaviour (UB). The compiler can assume that UB does not happen. Hence, the compiler can assume that the variables are never uninitialized when passed as argument, which means that the codepaths that initializes them must be taken. In ff_seek_frame_binary, this means that the compiler can assume that the codepaths that initialize pos_min and pos_max are taken, which means that the conditions "if (sti->index_entries)" and "if (index >= 0)" can be optimized out. Current Clang git versions (upcoming Clang 14) enabled an optimization that does this, which broke the current version of this function (which intentionally left the variables uninitialized, but silencing warnings about being uninitialized). See [1] for discussion on the matter. [1] https://reviews.llvm.org/D105169#3069555 Signed-off-by: Martin Storsjö <martin@martin.st>
Diffstat (limited to 'libavcodec/avdct.h')
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