[media] si2157: Bounds check firmware

When reading the firmware and sending commands, the length
must be bounds checked to avoid overrunning the size of the command
buffer and smashing the stack if the firmware is not in the
expected format. Add the proper check.

Cc: stable@kernel.org
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

diff --git a/drivers/media/tuners/si2157.c b/drivers/media/tuners/si2157.c
index 507382160e5e7524022c782240c36f98c1b54871..ce157edd45fa1adb3dd382037dd421f8b8590091 100644 (file)
--- a/drivers/media/tuners/si2157.c
+++ b/drivers/media/tuners/si2157.c
@@ -166,6 +166,10 @@ static int si2157_init(struct dvb_frontend *fe)
 
        for (remaining = fw->size; remaining > 0; remaining -= 17) {
                len = fw->data[fw->size - remaining];
+               if (len > SI2157_ARGLEN) {
+                       dev_err(&client->dev, "Bad firmware length\n");
+                       goto err_release_firmware;
+               }
                memcpy(cmd.args, &fw->data[(fw->size - remaining) + 1], len);
                cmd.wlen = len;
                cmd.rlen = 1;