2018-08-14 13:04:30

by walter harms

[permalink] [raw]
Subject: re:[PATCH] libertas_tf: prevent underflow in process_cmdrequest()

If recvlength is less than MESSAGE_HEADER_LEN (4) we would end up
corrupting memory.

Fixes: c305a19a0d0a ("libertas_tf: usb specific functions")
Signed-off-by: Dan Carpenter <[email protected]>
---
This is from static analysis. I'm not positive that this is a real
bug, but it's harmless to check.

diff --git a/drivers/net/wireless/marvell/libertas_tf/if_usb.c
b/drivers/net/wireless/marvell/libertas_tf/if_usb.c
index e92fc5001171..789337ea676a 100644
--- a/drivers/net/wireless/marvell/libertas_tf/if_usb.c
+++ b/drivers/net/wireless/marvell/libertas_tf/if_usb.c
@@ -605,9 +605,10 @@ static inline void process_cmdrequest(int recvlength,
uint8_t *recvbuff,
{
unsigned long flags;
- if (recvlength > LBS_CMD_BUFFER_SIZE) {
+ if (recvlength < MESSAGE_HEADER_LEN ||
+ recvlength > LBS_CMD_BUFFER_SIZE) {
lbtf_deb_usbd(&cardp->udev->dev,
- "The receive buffer is too large\n");
+ "The receive buffer is invalid: %d\n", recvlength);

The wording here is a bit unfortunate, and give the user a false impression (at
least me).
The problem is the paketsize not the buffer.
therefor i suggest to change that into:
"received invalid paketsize %d\n"

just my 2 cents,

re,
wh
kfree_skb(skb);
return;
}