CVE-2022-49087 — rxrpc: fix a race in rxrpc_exit_net()

Affected: Linux

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

rxrpc: fix a race in rxrpc_exit_net()

Current code can lead to the following race:

CPU0 CPU1

rxrpc_exit_net() rxrpc_peer_keepalive_worker() if (rxnet->live)

rxnet->live = false; del_timer_sync(&rxnet->peer_keepalive_timer);

timer_reduce(&rxnet->peer_keepalive_timer, jiffies + delay);

cancel_work_sync(&rxnet->peer_keepalive_work);

rxrpc_exit_net() exits while peer_keepalive_timer is still armed, leading to use-after-free.

syzbot report was:

ODEBUG: free active (active state 0) object type: timer_list hint: rxrpc_peer_keepalive_timeout+0x0/0xb0 WARNING: CPU: 0 PID: 3660 at lib/debugobjects.c:505 debug_print_object+0x16e/0x250 lib/debugobjects.c:505 Modules linked in: CPU: 0 PID: 3660 Comm: kworker/u4:6 Not tainted 5.17.0-syzkaller-13993-g88e6c0207623 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: netns cleanup_net RIP: 0010:debug_print_object+0x16e/0x250 lib/debugobjects.c:505 Code: ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 af 00 00 00 48 8b 14 dd 00 1c 26 8a 4c 89 ee 48 c7 c7 00 10 26 8a e8 b1 e7 28 05 <0f> 0b 83 05 15 eb c5 09 01 48 83 c4 18 5b 5d 41 5c 41 5d 41 5e c3 RSP: 0018:ffffc9000353fb00 EFLAGS: 00010082 RAX: 0000…

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CVE-2022-49087 — rxrpc: fix a race in rxrpc_exit_net()