In the fate sample field_size is larger than the number of bytes
remaining in the buffer. Furthermore the bytes to bits conversion was
prone to integer overflow when sizing the GetBitContext.
Fixes CVE-2011-3947
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
---
libavcodec/mjpegbdec.c | 7 +++++--
1 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/libavcodec/mjpegbdec.c b/libavcodec/mjpegbdec.c
index 4ad17ab..e0dc5e1 100644
--- a/libavcodec/mjpegbdec.c
+++ b/libavcodec/mjpegbdec.c
@@ -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 */
@@ -111,8 +114,8 @@ 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;
if (ff_mjpeg_decode_sos(s, NULL, NULL) < 0 &&
--
1.7.7.3
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