[FFmpeg-devel] [PATCH][RFC] nsv seeking

[Jai Menon]

On Wed, Apr 22, 2009 at 5:10 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Tue, Apr 21, 2009 at 09:43:16PM +0530, Jai Menon wrote:
>> On Mon, Apr 20, 2009 at 11:48 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> > On Mon, Apr 20, 2009 at 08:03:40PM +0530, Jai Menon wrote:
>> >> On Mon, Apr 20, 2009 at 6:24 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> >> > On Sun, Apr 19, 2009 at 04:46:48PM +0530, Jai Menon wrote:
>> >> >> On 4/18/09, Fran?ois Revol <revol at free.fr> wrote:
>> >> > [...]
>> >> >> @@ -348,12 +349,22 @@ static int nsv_parse_NSVf_header(AVFormatContext *s, AVFormatParameters *ap)
>> >> >> ? ? ?PRINT(("NSV got infos; filepos %"PRId64"\n", url_ftell(pb)));
>> >> >>
>> >> >> ? ? ?if (table_entries_used > 0) {
>> >> >> + ? ? ? ?int i;
>> >> >> ? ? ? ? ?nsv->index_entries = table_entries_used;
>> >> >> ? ? ? ? ?if((unsigned)table_entries >= UINT_MAX / sizeof(uint32_t))
>> >> >> ? ? ? ? ? ? ?return -1;
>> >> >> - ? ? ? ?nsv->nsvs_file_offset = av_malloc(table_entries * sizeof(uint32_t));
>> >> >> -#warning "FIXME: Byteswap buffer as needed"
>> >> >> - ? ? ? ?get_buffer(pb, (unsigned char *)nsv->nsvs_file_offset, table_entries * sizeof(uint32_t));
>> >> >> + ? ? ? ?nsv->nsvs_file_offset = av_malloc((unsigned)table_entries_used * sizeof(uint32_t));
>> >> >> +
>> >> >> + ? ? ? ?for(i=0;i<table_entries_used;i++)
>> >> >> + ? ? ? ? ? ?nsv->nsvs_file_offset[i] = get_le32(pb) + size;
>> >> >
>> >> > exploitable
>> >>
>> >> I can't think of any feasible attack vector here. Could you be a little verbose.
>> >
>> > table_entries_used * 4 overflows
>>
>> So you want the file offset table entries to be 64 bit?
>
> no i want you to make sure you allocate a table that is capable to
> hold the number of entries you write into it

Sorry, I don't quite understand. There are table_entries_used no.of
entries in the file offset table. And I'm writing exactly those amount
to the buffer.


-- 
Regards,

Jai