[FFmpeg-devel,FFmpeg-cvslog] avcodec/alsdec: Fix reading 0 mantisse bits

Am 09.09.16 um 09:11 schrieb Thilo Borgmann:
> Am 08.09.16 um 23:41 schrieb James Almer:
>>> ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu Sep  8 22:02:44 2016 +0200| [037422178d7f1d0dd09e1ce424dd61a69e77668b] | committer: Michael Niedermayer
>>>
>>> avcodec/alsdec: Fix reading 0 mantisse bits
>>>
>>> Fixes assertion failure
>>> Fixes: 848c24abc1721c9e3d1ba7bfee8d9fcc/asan_heap-oob_1d99eca_3709_567bba70d67e7d62714dcf56f26fb1da.mp4
>>>
>>> Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
>>> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
>>>
>>>> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=037422178d7f1d0dd09e1ce424dd61a69e77668b
>>> ---
>>>
>>>  libavcodec/alsdec.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
>>> index 1bb71f5..8c4ff53 100644
>>> --- a/libavcodec/alsdec.c
>>> +++ b/libavcodec/alsdec.c
>>> @@ -1527,7 +1527,7 @@ static int read_diff_float_data(ALSDecContext *ctx, unsigned int ra_frame) {
>>>              if (!get_bits1(gb)) { //uncompressed
>>>                  for (i = 0; i < frame_length; ++i) {
>>>                      if (ctx->raw_samples[c][i] != 0) {
>>> -                        raw_mantissa[c][i] = get_bits(gb, nbits[i]);
>>> +                        raw_mantissa[c][i] = nbits[i] ? get_bits(gb, nbits[i]) : 0;
>>
>> No point changing it now, but keep in mind for future reference that there's a get_bitsz()
>> function. It in fact expands to this same code you wrote.
> 
> Thanks!
> 
> Will fix it soon anyway otherwise I will forget about it.

Patch attached. Somebody please push, I can not do that from this computer.

Thanks,
Thilo
From 0cdbf565a9b43f8770e77ae2b2b1a0bfb60b0b68 Mon Sep 17 00:00:00 2001
From: Thilo Borgmann <thilo.borgmann@mail.de>
Date: Fri, 9 Sep 2016 12:29:23 +0200
Subject: [PATCH] lavc/alsdec: use get_bitsz() to simplify reading of the
 mantissa

---
 libavcodec/alsdec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

On 9/9/2016 7:35 AM, Thilo Borgmann wrote:
> Am 09.09.16 um 09:11 schrieb Thilo Borgmann:
>> > Am 08.09.16 um 23:41 schrieb James Almer:
>>>> >>> ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu Sep  8 22:02:44 2016 +0200| [037422178d7f1d0dd09e1ce424dd61a69e77668b] | committer: Michael Niedermayer
>>>> >>>
>>>> >>> avcodec/alsdec: Fix reading 0 mantisse bits
>>>> >>>
>>>> >>> Fixes assertion failure
>>>> >>> Fixes: 848c24abc1721c9e3d1ba7bfee8d9fcc/asan_heap-oob_1d99eca_3709_567bba70d67e7d62714dcf56f26fb1da.mp4
>>>> >>>
>>>> >>> Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
>>>> >>> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
>>>> >>>
>>>>> >>>> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=037422178d7f1d0dd09e1ce424dd61a69e77668b
>>>> >>> ---
>>>> >>>
>>>> >>>  libavcodec/alsdec.c | 2 +-
>>>> >>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>> >>>
>>>> >>> diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
>>>> >>> index 1bb71f5..8c4ff53 100644
>>>> >>> --- a/libavcodec/alsdec.c
>>>> >>> +++ b/libavcodec/alsdec.c
>>>> >>> @@ -1527,7 +1527,7 @@ static int read_diff_float_data(ALSDecContext *ctx, unsigned int ra_frame) {
>>>> >>>              if (!get_bits1(gb)) { //uncompressed
>>>> >>>                  for (i = 0; i < frame_length; ++i) {
>>>> >>>                      if (ctx->raw_samples[c][i] != 0) {
>>>> >>> -                        raw_mantissa[c][i] = get_bits(gb, nbits[i]);
>>>> >>> +                        raw_mantissa[c][i] = nbits[i] ? get_bits(gb, nbits[i]) : 0;
>>> >>
>>> >> No point changing it now, but keep in mind for future reference that there's a get_bitsz()
>>> >> function. It in fact expands to this same code you wrote.
>> > 
>> > Thanks!
>> > 
>> > Will fix it soon anyway otherwise I will forget about it.
> Patch attached. Somebody please push, I can not do that from this computer.

Pushed.

> 
> Thanks,
> Thilo
> 
> 
> 0001-lavc-alsdec-use-get_bitsz-to-simplify-reading-of-the.patch
> 
> 
> From 0cdbf565a9b43f8770e77ae2b2b1a0bfb60b0b68 Mon Sep 17 00:00:00 2001
> From: Thilo Borgmann <thilo.borgmann@mail.de>
> Date: Fri, 9 Sep 2016 12:29:23 +0200
> Subject: [PATCH] lavc/alsdec: use get_bitsz() to simplify reading of the
>  mantissa
> 
> ---
>  libavcodec/alsdec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
> index 8c4ff53..3986347 100644
> --- a/libavcodec/alsdec.c
> +++ b/libavcodec/alsdec.c
> @@ -1527,7 +1527,7 @@ static int read_diff_float_data(ALSDecContext *ctx, unsigned int ra_frame) {
>              if (!get_bits1(gb)) { //uncompressed
>                  for (i = 0; i < frame_length; ++i) {
>                      if (ctx->raw_samples[c][i] != 0) {
> -                        raw_mantissa[c][i] = nbits[i] ? get_bits(gb, nbits[i]) : 0;
> +                        raw_mantissa[c][i] = get_bitsz(gb, nbits[i]);
>                      }
>                  }
>              } else { //compressed
> -- 2.5.4 (Apple Git-61)
> 
> 
> 
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