In the Linux kernel, the following vulnerability has been resolved: net: mana: Add NULL guards in teardown path to prevent panic on attach

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

net: mana: Add NULL guards in teardown path to prevent panic on attach failure

When queue allocation fails partway through, the error cleanup frees
and NULLs apc->tx_qp and apc->rxqs. Multiple teardown paths such as
mana_remove(), mana_change_mtu() recovery, and internal error handling
in mana_alloc_queues() can subsequently call into functions that
dereference these pointers without NULL checks:

• mana_chn_setxdp() dereferences apc->rxqs[0], causing a NULL pointer
  dereference panic (CR2: 0000000000000000 at mana_chn_setxdp+0x26).
• mana_destroy_vport() iterates apc->rxqs without a NULL check.
• mana_fence_rqs() iterates apc->rxqs without a NULL check.
• mana_dealloc_queues() iterates apc->tx_qp without a NULL check.

Add NULL guards for apc->rxqs in mana_fence_rqs(),
mana_destroy_vport(), and before the mana_chn_setxdp() call. Add a
NULL guard for apc->tx_qp in mana_dealloc_queues() to skip TX queue
draining when TX queues were never allocated or already freed.