Re: [PATCH net] can: peak_usb: fix double free of transfer buffer on URB submit error

[Vincent Mailhol <mailhol@kernel.org>]

On 16/06/2026 at 20:15, Maoyi Xie wrote:
> In peak_usb_start(), each RX URB transfer buffer is allocated with kmalloc()
> and the URB is flagged URB_FREE_BUFFER so that the final usb_free_urb() also
> frees the transfer buffer.
> 
> If usb_submit_urb() fails, the error path frees the buffer explicitly with
> kfree(buf) and then calls usb_free_urb(urb). Because URB_FREE_BUFFER is set,
> usb_free_urb() -> urb_destroy() frees the same buffer a second time, a double
> free of the transfer buffer.
> 
>   BUG: KASAN: double-free in usb_free_urb.part.0+0x91/0xb0
>   Free of addr ffff8881069ccb80 by task trigger.sh/285
> 
>   Call Trace:
>    kfree+0x113/0x3c0
>    usb_free_urb.part.0+0x91/0xb0
> 
> Drop the redundant kfree(buf); usb_free_urb() already releases the transfer
> buffer. This mirrors commit 03819abbeb11 ("net: usb: lan78xx: Fix double free
> issue with interrupt buffer allocation").
> 
> Fixes: bb4785551f64 ("can: usb: PEAK-System Technik USB adapters driver core")
> Closes: https://lore.kernel.org/linux-can/178159320216.2154888.16953451793788581739@maoyixie.com/T/#u
> Cc: stable@vger.kernel.org
> Signed-off-by: Maoyi Xie <maoyixie.tju@gmail.com>

Reviewed-by: Vincent Mailhol <mailhol@kernel.org>


Yours sincerely,
Vincent Mailhol