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Message-ID: <20250718172746.1268813-1-chen.dylane@linux.dev>
Date: Sat, 19 Jul 2025 01:27:46 +0800
From: Tao Chen <chen.dylane@...ux.dev>
To: pablo@...filter.org,
kadlec@...filter.org,
davem@...emloft.net,
edumazet@...gle.com,
kuba@...nel.org,
pabeni@...hat.com,
horms@...nel.org,
ast@...nel.org,
fw@...len.de
Cc: netfilter-devel@...r.kernel.org,
coreteam@...filter.org,
netdev@...r.kernel.org,
linux-kernel@...r.kernel.org,
bpf@...r.kernel.org,
Tao Chen <chen.dylane@...ux.dev>,
syzbot+92c5daf9a23f04ccfc99@...kaller.appspotmail.com
Subject: [PATCH bpf-next] netfilter: bpf: Disable migrate before bpf_prog run
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:
<TASK>
__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@...kaller.appspotmail.com
Signed-off-by: Tao Chen <chen.dylane@...ux.dev>
---
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
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