[vlc-devel] [PATCH] demux: stl: fix heap-buffer-overflow

[Shaleen Jain]

Oh sorry, I meant; add a guard to prevent attempting allocation if we 
have 0 elements.
Zero elements are not  valid and allocating 0 stl_entry_t may or may 
not return a NULL pointer.
Regards,
Shaleen Jain

On Tue, Jul 4, 2017 at 4:41 PM, Rémi Denis-Courmont <remi at remlab.net> 
wrote:
> Le 4 juillet 2017 10:16:41 GMT+03:00, Shaleen Jain 
> <shaleen.jain95 at gmail.com> a écrit :
>> According to the spec calloc can return a NULL or a unique pointer
>> value if either of the arguments are 0 depending on the 
>> implementation.
>> 
>> Add a guard to prevent member access if we get a non-null pointer in
>> the above case.
>> ---
>>  modules/demux/stl.c | 2 ++
>>  1 file changed, 2 insertions(+)
>> 
>> diff --git a/modules/demux/stl.c b/modules/demux/stl.c
>> index 9a0d5a131e..9d27a79458 100644
>> --- a/modules/demux/stl.c
>> +++ b/modules/demux/stl.c
>> @@ -243,6 +243,8 @@ static int Open(vlc_object_t *object)
>>      const mtime_t program_start = ParseTextTimeCode(&header[256], 
>> fps);
>>      const size_t tti_count = ParseInteger(&header[238], 5);
>>      msg_Dbg(demux, "Detected EBU STL : CCT=%d TTI=%zu start=%8.8s 
>> %"PRId64, cct, tti_count, &header[256], program_start);
>> +    if(!tti_count)
>> +        return VLC_EGENERIC;
>> 
>>      demux_sys_t *sys = malloc(sizeof(*sys));
>>      if(!sys)
> 
> I am confused by the description here. If 0 elements is a valid 
> situation, then the error predicate is wrong as NULL would be 
> conditionally valid return.
> --
> Rémi Denis-Courmont
> Typed on an inconvenient virtual keyboard
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.videolan.org/pipermail/vlc-devel/attachments/20170704/4518d43d/attachment.html>