From: Eric Dumazet edumazet@google.com
[ Upstream commit 1946014ca3b19be9e485e780e862c375c6f98bad ]
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: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000 RDX: ffff888029196140 RSI: ffffffff815efad8 RDI: fffff520006a7f52 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff815ea4ae R11: 0000000000000000 R12: ffffffff89ce23e0 R13: ffffffff8a2614e0 R14: ffffffff816628c0 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe1f2908924 CR3: 0000000043720000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> __debug_check_no_obj_freed lib/debugobjects.c:992 [inline] debug_check_no_obj_freed+0x301/0x420 lib/debugobjects.c:1023 kfree+0xd6/0x310 mm/slab.c:3809 ops_free_list.part.0+0x119/0x370 net/core/net_namespace.c:176 ops_free_list net/core/net_namespace.c:174 [inline] cleanup_net+0x591/0xb00 net/core/net_namespace.c:598 process_one_work+0x996/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 </TASK>
Fixes: ace45bec6d77 ("rxrpc: Fix firewall route keepalive") Signed-off-by: Eric Dumazet edumazet@google.com Cc: David Howells dhowells@redhat.com Cc: Marc Dionne marc.dionne@auristor.com Cc: linux-afs@lists.infradead.org Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/rxrpc/net_ns.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/rxrpc/net_ns.c b/net/rxrpc/net_ns.c index b312aab80fed..9a76b74af37b 100644 --- a/net/rxrpc/net_ns.c +++ b/net/rxrpc/net_ns.c @@ -116,8 +116,8 @@ static __net_exit void rxrpc_exit_net(struct net *net) struct rxrpc_net *rxnet = rxrpc_net(net);
rxnet->live = false; - del_timer_sync(&rxnet->peer_keepalive_timer); cancel_work_sync(&rxnet->peer_keepalive_work); + del_timer_sync(&rxnet->peer_keepalive_timer); rxrpc_destroy_all_calls(rxnet); rxrpc_destroy_all_connections(rxnet); rxrpc_destroy_all_peers(rxnet);