CVE-2026-74456: can: peak_usb: peak_usb_start(): fix double free of transfer buffer on URB submit error

From: Greg Kroah-Hartman <[email protected]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

can: peak_usb: peak_usb_start(): fix double free of transfer buffer on URB submit error

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").

The Linux kernel CVE team has assigned CVE-2026-74456 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 3.4 with commit bb4785551f64e18b2c8bb15a3bd2b22f5ebf624d and fixed in 6.6.151 with commit 525640b93d3e5f82f4ebea4730f4e0cf799522ba
	Issue introduced in 3.4 with commit bb4785551f64e18b2c8bb15a3bd2b22f5ebf624d and fixed in 6.12.103 with commit 4bb3325075138dd5346b71589a959878b564dc0b
	Issue introduced in 3.4 with commit bb4785551f64e18b2c8bb15a3bd2b22f5ebf624d and fixed in 6.18.44 with commit 92d0de80ca2223b9c7da78020155b6cb27824cc0
	Issue introduced in 3.4 with commit bb4785551f64e18b2c8bb15a3bd2b22f5ebf624d and fixed in 7.1.8 with commit dfb17bf04a764462000f11258a7c06aa92d1f261
	Issue introduced in 3.4 with commit bb4785551f64e18b2c8bb15a3bd2b22f5ebf624d and fixed in 7.2-rc6 with commit 9b3d5a6d952c38bbcf07f903cbeadefdb56b9bc9

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-74456
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/net/can/usb/peak_usb/pcan_usb_core.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/525640b93d3e5f82f4ebea4730f4e0cf799522ba
	https://git.kernel.org/stable/c/4bb3325075138dd5346b71589a959878b564dc0b
	https://git.kernel.org/stable/c/92d0de80ca2223b9c7da78020155b6cb27824cc0
	https://git.kernel.org/stable/c/dfb17bf04a764462000f11258a7c06aa92d1f261
	https://git.kernel.org/stable/c/9b3d5a6d952c38bbcf07f903cbeadefdb56b9bc9