[FFmpeg-devel] [PATCH] ARMovie/RPL demuxer rev4
Sat Mar 29 02:15:09 CET 2008
On Fri, Mar 28, 2008 at 6:06 PM, M?ns Rullg?rd <mans at mansr.com> wrote:
> "Eli Friedman" <eli.friedman at gmail.com> writes:
> > On Fri, Mar 28, 2008 at 4:38 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> >> On Fri, Mar 28, 2008 at 04:13:02PM -0700, Eli Friedman wrote:
> >> > + if (offset >= 0xFFFFFFFFUL || video_size >= 0xFFFFFFFFUL ||
> >> > + audio_size >= 0xFFFFFFFFUL)
> >> > + error |= -1;
> >> What exactly is this check good for?
> > Overflow, so it doesn't silently accept 10000000000000 as an offset.
> Quoting the C99 section on sscanf:
> [...] if the result of the conversion cannot be represented in the
> object, the behavior is undefined.
> This means that if the input contains a number too large for, in your
> case, a long, anything could be returned, including a seemingly
> sensible value. Those checks are thus pointless. If input validation
> at stage is a concern, don't use sscanf().
Oh, hmm, okay. I had assumed that all sscanf implementations would
act like the glibc one and strtoul, which return 0xFFFFFFFF for
out-of-range unsigned values.
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