[PATCH] firewire: prevent integer overflow on 32bit systems

[Dan Carpenter]

In TCODE_STREAM_DATA mode, on 32bit systems, the "sizeof(*e) +
request->length" operation can overflow leading to memory corruption.

Fixes: 18e9b10fcdc0 ("firewire: cdev: add closure to async stream ioctl")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
 drivers/firewire/core-cdev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index fb6c651214f3..314de0384035 100644
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -587,6 +587,9 @@ static int init_request(struct client *client,
 	    request->length < 4)
 		return -EINVAL;
 
+	if (request->length > ULONG_MAX - sizeof(*e))
+		return -EINVAL;
+
 	e = kmalloc(sizeof(*e) + request->length, GFP_KERNEL);
 	if (e == NULL)
 		return -ENOMEM;
-- 
2.30.1