On 12 September 2013 17:14, Arthur Mesh via RT <r...@openssl.org> wrote:
> I am not 100% sure this is a real bug, hence first tried mailing
> openssl-users instead of rt@. But since there was no reply, I am sending
> this to rt@
>
>
> 641 if (is_sslv3)
> 642 {
> <snip>
> 647 unsigned overhang =
> header_length-md_block_size;
> 648 md_transform(md_state.c, header);
> 649 memcpy(first_block, header + md_block_size,
> overhang);
>
> My suspicion lies in line 649, where we're copying overhang number of bytes
> from (header + md_block_size). I believe that copying from (header +
> md_block_size) is out-of-bound access (overrun).
>
> header is an array of 13 unsigned chars, and md_block_size == 64 (or 128
> in some
> cases). Hence (header + md_block_size) points outside of header[13].
> Assuming
> overhang > 0, by doing a memcpy(), we have a problem, no?
>
Well, in fact, this code is only run when |is_sslv3|, and in that case,
|header| is actually 75 bytes. So, the documentation is at fault.
But I guess an interesting question is: can |md_block_size| be 128 when
|is_sslv3|?
