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

bridge: stp: Fix a potential use-after-free when deleting a bridge

The three STP timers are not supposed to be armed while the bridge is
administratively down. They are synchronously deactivated when the
bridge is put administratively down and the various call sites check for
'IFF_UP' before arming them.

This check is missing from br_topology_change_detection() and it is
possible to engineer a situation in which the topology change timer is
armed while the bridge is administratively down, resulting in a
use-after-free [1] when the bridge is deleted.

Fix by adding the missing check and for good measures synchronously
shutdown the three timers when the bridge is deleted.

[1]
ODEBUG: free active (active state 0) object: ffff88811662b9b0 object type: timer_list hint: br_topology_change_timer_expired (net/bridge/br_stp_timer.c:120)
WARNING: lib/debugobjects.c:629 at debug_print_object+0x1bc/0x450, CPU#9: ip/359

https://git.kernel.org/stable/c/297a747f59bff6573196d7236178144d66524e68

https://git.kernel.org/stable/c/2a00517db8de4be7df3d483b215c5544fb30a191

https://git.kernel.org/stable/c/39283907a25e5caf0f2bd2947f6e56644b01e2b7

https://git.kernel.org/stable/c/40cbfa3a28e0919469d1b086629bb3ce38a83593

https://git.kernel.org/stable/c/4c40eec06eeac37c58e47a6058eb32901218d5d4

https://git.kernel.org/stable/c/b4b3458ef88df4798632619f018791d4344bcd92

https://git.kernel.org/stable/c/c86579b0a2d201792bcb59316629f4ba4758cfc8

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