diff mbox series

media: av7110: prevent underflow in write_ts_to_decoder()

Message ID 9dbe6804-7fac-4ee1-9e70-c3648cb60ec8@kili.mountain (mailing list archive)
State Accepted
Delegated to: Hans Verkuil
Headers
Series media: av7110: prevent underflow in write_ts_to_decoder() |

Commit Message

Dan Carpenter March 7, 2023, 10 a.m. UTC 
  The buf[4] value comes from the user via ts_play().  It is a value in
the u8 range.  The final length we pass to av7110_ipack_instant_repack()
is "len - (buf[4] + 1) - 4" so add a check to ensure that the length is
not negative.  It's not clear that passing a negative len value does
anything bad necessarily, but it's not best practice.

With the new bounds checking the "if (!len)" condition is no longer
possible or required so remove that.

Fixes: fd46d16d602a ("V4L/DVB (11759): dvb-ttpci: Add TS replay capability")
Signed-off-by: Dan Carpenter <error27@gmail.com>
---
This is from static analysis and not tested.  I debated whether to
return 0 or -1.

 drivers/staging/media/av7110/av7110_av.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/staging/media/av7110/av7110_av.c b/drivers/staging/media/av7110/av7110_av.c
index 0bf513c26b6b..a5c5bebad306 100644
--- a/drivers/staging/media/av7110/av7110_av.c
+++ b/drivers/staging/media/av7110/av7110_av.c
@@ -823,10 +823,10 @@  static int write_ts_to_decoder(struct av7110 *av7110, int type, const u8 *buf, s
 		av7110_ipack_flush(ipack);
 
 	if (buf[3] & ADAPT_FIELD) {
+		if (buf[4] > len - 1 - 4)
+			return 0;
 		len -= buf[4] + 1;
 		buf += buf[4] + 1;
-		if (!len)
-			return 0;
 	}
 
 	av7110_ipack_instant_repack(buf + 4, len - 4, ipack);