Re: [PATCH] can: mcba_usb: fix memory leak in mcba_usb

On 10.06.2021 00:58:33, Pavel Skripkin wrote:

Syzbot reported memory leak in SocketCAN driver
for Microchip CAN BUS Analyzer Tool. The problem
was in unfreed usb_coherent.

In mcba_usb_start() 20 coherent buffers are allocated
and there is nothing, that frees them:

	1) In callback function the urb is resubmitted and that's all
	2) In disconnect function urbs are simply killed, but
	   URB_FREE_BUFFER is not set (see mcba_usb_start)
           and this flag cannot be used with coherent buffers.

Fail log:
[ 1354.053291][ T8413] mcba_usb 1-1:0.0 can0: device disconnected
[ 1367.059384][ T8420] kmemleak: 20 new suspected memory leaks (see /sys/kernel/debug/kmem)

So, all allocated buffers should be freed with usb_free_coherent()
explicitly

NOTE:
The same pattern for allocating and freeing coherent buffers
is used in drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c

Fixes: 51f3baad7de9 ("can: mcba_usb: Add support for Microchip CAN BUS Analyzer")
Reported-and-tested-by: syzbot+57281c762a3922e14dfe@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <redacted>

Applied to linux-can/testing.

Tnx,
Marc

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