From: Eric Dumazet edumazet@google.com
[ Upstream commit 8d61f926d42045961e6b65191c09e3678d86a9cf ]
syzbot reported a possible deadlock in netlink_set_err() [1]
A similar issue was fixed in commit 1d482e666b8e ("netlink: disable IRQs for netlink_lock_table()") in netlink_lock_table()
This patch adds IRQ safety to netlink_set_err() and __netlink_diag_dump() which were not covered by cited commit.
[1]
WARNING: possible irq lock inversion dependency detected 6.4.0-rc6-syzkaller-00240-g4e9f0ec38852 #0 Not tainted
syz-executor.2/23011 just changed the state of lock: ffffffff8e1a7a58 (nl_table_lock){.+.?}-{2:2}, at: netlink_set_err+0x2e/0x3a0 net/netlink/af_netlink.c:1612 but this lock was taken by another, SOFTIRQ-safe lock in the past: (&local->queue_stop_reason_lock){..-.}-{2:2}
and interrupts could create inverse lock ordering between them.
other info that might help us debug this: Possible interrupt unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(nl_table_lock); local_irq_disable(); lock(&local->queue_stop_reason_lock); lock(nl_table_lock); <Interrupt> lock(&local->queue_stop_reason_lock);
*** DEADLOCK ***
Fixes: 1d482e666b8e ("netlink: disable IRQs for netlink_lock_table()") Reported-by: syzbot+a7d200a347f912723e5c@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=a7d200a347f912723e5c Link: https://lore.kernel.org/netdev/000000000000e38d1605fea5747e@google.com/T/#u Signed-off-by: Eric Dumazet edumazet@google.com Cc: Johannes Berg johannes.berg@intel.com Link: https://lore.kernel.org/r/20230621154337.1668594-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/netlink/af_netlink.c | 5 +++-- net/netlink/diag.c | 5 +++-- 2 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 3a1e0fd5bf149..5968b6450d828 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -1600,6 +1600,7 @@ static int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p) int netlink_set_err(struct sock *ssk, u32 portid, u32 group, int code) { struct netlink_set_err_data info; + unsigned long flags; struct sock *sk; int ret = 0;
@@ -1609,12 +1610,12 @@ int netlink_set_err(struct sock *ssk, u32 portid, u32 group, int code) /* sk->sk_err wants a positive error value */ info.code = -code;
- read_lock(&nl_table_lock); + read_lock_irqsave(&nl_table_lock, flags);
sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list) ret += do_one_set_err(sk, &info);
- read_unlock(&nl_table_lock); + read_unlock_irqrestore(&nl_table_lock, flags); return ret; } EXPORT_SYMBOL(netlink_set_err); diff --git a/net/netlink/diag.c b/net/netlink/diag.c index c6255eac305c7..4143b2ea4195a 100644 --- a/net/netlink/diag.c +++ b/net/netlink/diag.c @@ -94,6 +94,7 @@ static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb, struct net *net = sock_net(skb->sk); struct netlink_diag_req *req; struct netlink_sock *nlsk; + unsigned long flags; struct sock *sk; int num = 2; int ret = 0; @@ -152,7 +153,7 @@ static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb, num++;
mc_list: - read_lock(&nl_table_lock); + read_lock_irqsave(&nl_table_lock, flags); sk_for_each_bound(sk, &tbl->mc_list) { if (sk_hashed(sk)) continue; @@ -173,7 +174,7 @@ static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb, } num++; } - read_unlock(&nl_table_lock); + read_unlock_irqrestore(&nl_table_lock, flags);
done: cb->args[0] = num;