[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>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/media/tuners/si2157.c b/drivers/media/tuners/si2157.c
index 507382160e5e..ce157edd45fa 100644
--- 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;