[FFmpeg-devel] [PATCH] Fix the wmavoice-7k fate test (failures on OpenBSD)

[Ronald S. Bultje]

Hi,

On Sat, Aug 7, 2010 at 6:12 AM, Martin Storsj? <martin at martin.st> wrote:
> I checked out the wmavoice-7k fate test failures that occurred on OpenBSD,
> and actually got crashes in these tests on Mac OS X, too, under some
> compilation configurations.
>
> I tracked down the issue to aw_pulse_set2, where the loop around lines
> 1071- may write outside of the use_mask buffer if pulse_off starts out
> negative.
>
> The first patch fixes the issue and makes the test pass on OpenBSD, but
> it's a bit ugly. The second patch also fixes the issue, but changes the
> output of the test (but it still sounds the same to me). I believe this is
> the more correct way to fix the issue, but requires the reference sample
> in the testsuite to be updated.

I think neither are correct. The pulse exclusion length should not be
affected, but the ones with a negative offset should be skipped. Given
that, the second patch is definitely wrong, but the first patch is
probably not right either.

Since checking length and recalculating length, offset (and so on)
would affect speed significantly, I feel the better (and safer) thing
to do is to pad use_mask with two uint16_ts _before_ the pointer start
(similar to how we pad it with two uint16_ts _after_ currently). That
way, even if idx is the minimum value (-23), it would still write in
valid memory (use_mask[-23 >> 4] = use_mask[-2]). these values should
be initialized to zero, similar to the post-use_mask-pad values. At
the same time, no length checks are necessary, and thus the code is
safe even with negative offset values.

Ronald