CVE-2025-39873

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

can: xilinx_can: xcan_write_frame(): fix use-after-free of transmitted SKB

can_put_echo_skb() takes ownership of the SKB and it may be freed during or after the call.

However, xilinx_can xcan_write_frame() keeps using SKB after the call.

Fix that by only calling can_put_echo_skb() after the code is done touching the SKB.

The tx_lock is held for the entire xcan_write_frame() execution and also on the can_get_echo_skb() side so the order of operations does not matter.

An earlier fix commit 3d3c817c3a40 ("can: xilinx_can: Fix usage of skb memory") did not move the can_put_echo_skb() call far enough.

[mkl: add "commit" in front of sha1 in patch description] [mkl: fix indention]

This flaw represents minimal risk to Red Hat environments because the vulnerable code is not present in supported Red Hat Enterprise Linux releases. Furthermore, the affected driver targets Xilinx Controller Area Network (CAN) hardware controllers, which are specific to embedded platforms and not utilized in standard enterprise server environments. Consequently, standard enterprise installations are not exposed to this vulnerability.