[PATCHv2] si2157: Bounds check firmware

[Laura Abbott <labbott@fedoraproject.org>]

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>
---
v2: Set the return code properly
---
 drivers/media/tuners/si2157.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/media/tuners/si2157.c b/drivers/media/tuners/si2157.c
index 5073821..0e1ca2b 100644
--- a/drivers/media/tuners/si2157.c
+++ b/drivers/media/tuners/si2157.c
@@ -166,6 +166,11 @@ 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");
+			ret = -EINVAL;
+			goto err_release_firmware;
+		}
 		memcpy(cmd.args, &fw->data[(fw->size - remaining) + 1], len);
 		cmd.wlen = len;
 		cmd.rlen = 1;
-- 
2.4.3