mjpegbdec: Fix overflow in SOS.

Based in part by a fix from Michael Niedermayer <michaelni@gmx.at>

Fixes CVE-2011-3947

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
(cherry picked from commit b57d262412)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>
(cherry picked from commit 083a8a0037)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>
This commit is contained in:
Alex Converse 2012-01-25 13:39:24 -08:00 committed by Reinhard Tartler
parent 96ed18cab1
commit 6ae95a0b93
1 changed files with 5 additions and 2 deletions

View File

@ -59,6 +59,9 @@ read_header:
s->restart_count = 0;
s->mjpb_skiptosod = 0;
if (buf_end - buf_ptr >= 1 << 28)
return AVERROR_INVALIDDATA;
init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
skip_bits(&hgb, 32); /* reserved zeros */
@ -109,8 +112,8 @@ read_header:
av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs);
if (sos_offs)
{
// init_get_bits(&s->gb, buf+sos_offs, (buf_end - (buf+sos_offs))*8);
init_get_bits(&s->gb, buf_ptr+sos_offs, field_size*8);
init_get_bits(&s->gb, buf_ptr + sos_offs,
8 * FFMIN(field_size, buf_end - buf_ptr - sos_offs));
s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
s->start_code = SOS;
ff_mjpeg_decode_sos(s, NULL, NULL);