[FFmpeg-devel] FFv1 race condition backport

Michael Niedermayer michael at niedermayer.cc
Tue Aug 5 14:12:32 EEST 2025


Hi everyone

If someone wants the FFv1 frame threading race fix backported:
its these 2 commits:
8d5efc218245c3f0559f48837b3e63e2932525e0 and bcf08c11710cab5db8eb3d0774e1a93e322fb821

If these are not backported, our choice is to leave the bug or to disable
frame threading in favor of slice threading
ATM all release branches prior to 7.1 disable the code because of this
bug

(we could also make slice threading the default and leave frame threading
 as an option, that would probably need a check for FFv1 outside the ffv1 codec)

i have a testcase that reliably triggers the bug and hits an assertion
(if asserts are enabled, i suspect its possible to construct a out of array
 access for this with enough effort but i have no testcase for that)

I have too much on my todo ATM to backport this, especially as simply
switching to slice threading (or upgrading to 7.1) fixes it.

thx

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The misfortune of the wise is better than the prosperity of the fool.
-- Epicurus
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