[PATCH 4.1 15/86] [media] si2157: Bounds check firmware

[Greg Kroah-Hartman]

4.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Laura Abbott <labbott@xxxxxxxxxxxxxxxxx>

commit a828d72df216c36e9c40b6c24dc4b17b6f7b5a76 upstream.

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.

Signed-off-by: Laura Abbott <labbott@xxxxxxxxxxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/media/tuners/si2157.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/media/tuners/si2157.c
+++ b/drivers/media/tuners/si2157.c
@@ -165,6 +165,10 @@ static int si2157_init(struct dvb_fronte
 
 	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;


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