[FFmpeg-devel] [PATCH] avcodec/flacdsp: Avoid undefined operations in non debug builds

Michael Niedermayer michael at niedermayer.cc
Sat Feb 4 04:02:19 EET 2017

On Thu, Dec 15, 2016 at 01:32:18AM +0100, Michael Niedermayer wrote:
> This fixes ubsan warnings in non debug builds by using unsigned operations
> in debug builds the correct signed operations are retained so that overflows
> (which should not occur in valid files and may indicate problems in the DSP code
> or decoder) can be detected.
> Alternatively they can be changed to unsigned unconditionally, then its
> not possible though to detect overflows easily if someone wants to test
> the DSP code for overflows.
> The 2nd alternative would be to leave the code as it is and accept that
> there are undefined operations in the DSP code and that ubsan output is
> full of them in some cases.
> Similar changes would be needed in some other DSP routines
> Suggested-by: Matt Wolenetz <wolenetz at google.com>
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavcodec/flacdsp.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If you drop bombs on a foreign country and kill a hundred thousand
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"unprovoked inhuman terrorist attacks" and use it to justify dropping
more bombs and killing more people. The technology changed, the idea is old.
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