syzkaller reported an issue: BUG: assuming non migratable context at ./include/linux/filter.h:703 in_atomic(): 0, irqs_disabled(): 0, migration_disabled() 0 pid: 5829, name: sshd-session 3 locks held by sshd-session/5829: #0: ffff88807b4e4218 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1667 [inline] #0: ffff88807b4e4218 (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_sendmsg+0x20/0x50 net/ipv4/tcp.c:1395 #1: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #1: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #1: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: __ip_queue_xmit+0x69/0x26c0 net/ipv4/ip_output.c:470 #2: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #2: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #2: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: nf_hook+0xb2/0x680 include/linux/netfilter.h:241 CPU: 0 UID: 0 PID: 5829 Comm: sshd-session Not tainted 6.16.0-rc6-syzkaller-00002-g155a3c003e55 #0 PREEMPT(full) Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120 __cant_migrate kernel/sched/core.c:8860 [inline] __cant_migrate+0x1c7/0x250 kernel/sched/core.c:8834 __bpf_prog_run include/linux/filter.h:703 [inline] bpf_prog_run include/linux/filter.h:725 [inline] nf_hook_run_bpf+0x83/0x1e0 net/netfilter/nf_bpf_link.c:20 nf_hook_entry_hookfn include/linux/netfilter.h:157 [inline] nf_hook_slow+0xbb/0x200 net/netfilter/core.c:623 nf_hook+0x370/0x680 include/linux/netfilter.h:272 NF_HOOK_COND include/linux/netfilter.h:305 [inline] ip_output+0x1bc/0x2a0 net/ipv4/ip_output.c:433 dst_output include/net/dst.h:459 [inline] ip_local_out net/ipv4/ip_output.c:129 [inline] __ip_queue_xmit+0x1d7d/0x26c0 net/ipv4/ip_output.c:527 __tcp_transmit_skb+0x2686/0x3e90 net/ipv4/tcp_output.c:1479 tcp_transmit_skb net/ipv4/tcp_output.c:1497 [inline] tcp_write_xmit+0x1274/0x84e0 net/ipv4/tcp_output.c:2838 __tcp_push_pending_frames+0xaf/0x390 net/ipv4/tcp_output.c:3021 tcp_push+0x225/0x700 net/ipv4/tcp.c:759 tcp_sendmsg_locked+0x1870/0x42b0 net/ipv4/tcp.c:1359 tcp_sendmsg+0x2e/0x50 net/ipv4/tcp.c:1396 inet_sendmsg+0xb9/0x140 net/ipv4/af_inet.c:851 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg net/socket.c:727 [inline] sock_write_iter+0x4aa/0x5b0 net/socket.c:1131 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x6c7/0x1150 fs/read_write.c:686 ksys_write+0x1f8/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7 The cant_migrate() check in __bpf_prog_run requires to disable migrate before running the bpf_prog, it seems that migrate is not disabled in the above execution path. Fixes: fd9c663b9ad6 ("bpf: minimal support for programs hooked into netfilter framework") Reported-by: syzbot+92c5daf9a23f04ccfc99@syzkaller.appspotmail.com Signed-off-by: Tao Chen --- net/netfilter/nf_bpf_link.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/netfilter/nf_bpf_link.c b/net/netfilter/nf_bpf_link.c index a054d3b216d..b6ed1b844cc 100644 --- a/net/netfilter/nf_bpf_link.c +++ b/net/netfilter/nf_bpf_link.c @@ -11,13 +11,18 @@ static unsigned int nf_hook_run_bpf(void *bpf_prog, struct sk_buff *skb, const struct nf_hook_state *s) { + u32 ret; const struct bpf_prog *prog = bpf_prog; struct bpf_nf_ctx ctx = { .state = s, .skb = skb, }; - return bpf_prog_run(prog, &ctx); + migrate_disable(); + ret = bpf_prog_run(prog, &ctx); + migrate_enable(); + + return ret; } struct bpf_nf_link { -- 2.48.1