BUG: using smp_processor_id() in preemptible code in tipc_crypto_xmit

[syzbot <syzbot+263f8c0d007dc09b2dda@syzkaller.appspotmail.com>]

Hello,

syzbot found the following crash on:

HEAD commit:    f4926d51 Merge git://git.kernel.org/pub/scm/linux/kernel/g..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=137a899b100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=dcc6334acae363d4
dashboard link: https://syzkaller.appspot.com/bug?extid=263f8c0d007dc09b2dda
compiler:       gcc (GCC) 10.1.0-syz 20200507

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+263f8c0d007dc09b2dda@syzkaller.appspotmail.com

BUG: using smp_processor_id() in preemptible [00000000] code: syz-executor.1/23385
caller is tipc_aead_tfm_next net/tipc/crypto.c:402 [inline]
caller is tipc_aead_encrypt net/tipc/crypto.c:639 [inline]
caller is tipc_crypto_xmit+0x80a/0x2790 net/tipc/crypto.c:1605
CPU: 1 PID: 23385 Comm: syz-executor.1 Not tainted 5.8.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 check_preemption_disabled+0x20d/0x220 lib/smp_processor_id.c:48
 tipc_aead_tfm_next net/tipc/crypto.c:402 [inline]
 tipc_aead_encrypt net/tipc/crypto.c:639 [inline]
 tipc_crypto_xmit+0x80a/0x2790 net/tipc/crypto.c:1605
 tipc_bearer_xmit_skb+0x180/0x3f0 net/tipc/bearer.c:523
 tipc_enable_bearer+0xb1d/0xdc0 net/tipc/bearer.c:331
 __tipc_nl_bearer_enable+0x2bf/0x390 net/tipc/bearer.c:995
 tipc_nl_bearer_enable+0x1e/0x30 net/tipc/bearer.c:1003
 genl_family_rcv_msg_doit net/netlink/genetlink.c:691 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:736 [inline]
 genl_rcv_msg+0x61d/0x9e0 net/netlink/genetlink.c:753
 netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2469
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:764
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cb19
Code: Bad RIP value.
RSP: 002b:00007fa3c4dc1c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000501c40 RCX: 000000000045cb19
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000a19 R14: 00000000004ccf82 R15: 00007fa3c4dc26d4
tipc: Enabled bearer <eth:vlan1>, priority 10


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