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Date: Sun, 25 Jun 2023 09:13:34 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
<pabeni@...hat.com>
CC: Kuniyuki Iwashima <kuniyu@...zon.com>, Kuniyuki Iwashima
<kuni1840@...il.com>, <netdev@...r.kernel.org>,
<syzbot+5da61cf6a9bc1902d422@...kaller.appspotmail.com>
Subject: [PATCH v1 net] netlink: Add sock_i_ino_irqsaved() for __netlink_diag_dump().
syzbot reported a warning in __local_bh_enable_ip(). [0]
Commit 8d61f926d420 ("netlink: fix potential deadlock in
netlink_set_err()") converted read_lock(&nl_table_lock) to
read_lock_irqsave() in __netlink_diag_dump() to prevent a deadlock.
However, __netlink_diag_dump() calls sock_i_ino() that uses
read_lock_bh() and read_unlock_bh(). read_unlock_bh() finally
enables BH even though it should stay disabled until the following
read_unlock_irqrestore().
Using read_lock() in sock_i_ino() would trigger a lockdep splat
in another place that was fixed in commit f064af1e500a ("net: fix
a lockdep splat"), so let's add another function that would be safe
to use under BH disabled.
[0]:
WARNING: CPU: 0 PID: 5012 at kernel/softirq.c:376 __local_bh_enable_ip+0xbe/0x130 kernel/softirq.c:376
Modules linked in:
CPU: 0 PID: 5012 Comm: syz-executor487 Not tainted 6.4.0-rc7-syzkaller-00202-g6f68fc395f49 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
RIP: 0010:__local_bh_enable_ip+0xbe/0x130 kernel/softirq.c:376
Code: 45 bf 01 00 00 00 e8 91 5b 0a 00 e8 3c 15 3d 00 fb 65 8b 05 ec e9 b5 7e 85 c0 74 58 5b 5d c3 65 8b 05 b2 b6 b4 7e 85 c0 75 a2 <0f> 0b eb 9e e8 89 15 3d 00 eb 9f 48 89 ef e8 6f 49 18 00 eb a8 0f
RSP: 0018:ffffc90003a1f3d0 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000000000201 RCX: 1ffffffff1cf5996
RDX: 0000000000000000 RSI: 0000000000000201 RDI: ffffffff8805c6f3
RBP: ffffffff8805c6f3 R08: 0000000000000001 R09: ffff8880152b03a3
R10: ffffed1002a56074 R11: 0000000000000005 R12: 00000000000073e4
R13: dffffc0000000000 R14: 0000000000000002 R15: 0000000000000000
FS: 0000555556726300(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000045ad50 CR3: 000000007c646000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
sock_i_ino+0x83/0xa0 net/core/sock.c:2559
__netlink_diag_dump+0x45c/0x790 net/netlink/diag.c:171
netlink_diag_dump+0xd6/0x230 net/netlink/diag.c:207
netlink_dump+0x570/0xc50 net/netlink/af_netlink.c:2269
__netlink_dump_start+0x64b/0x910 net/netlink/af_netlink.c:2374
netlink_dump_start include/linux/netlink.h:329 [inline]
netlink_diag_handler_dump+0x1ae/0x250 net/netlink/diag.c:238
__sock_diag_cmd net/core/sock_diag.c:238 [inline]
sock_diag_rcv_msg+0x31e/0x440 net/core/sock_diag.c:269
netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2547
sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:280
netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1365
netlink_sendmsg+0x925/0xe30 net/netlink/af_netlink.c:1914
sock_sendmsg_nosec net/socket.c:724 [inline]
sock_sendmsg+0xde/0x190 net/socket.c:747
____sys_sendmsg+0x71c/0x900 net/socket.c:2503
___sys_sendmsg+0x110/0x1b0 net/socket.c:2557
__sys_sendmsg+0xf7/0x1c0 net/socket.c:2586
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f5303aaabb9
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc7506e548 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f5303aaabb9
RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000003
RBP: 00007f5303a6ed60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f5303a6edf0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Fixes: 8d61f926d420 ("netlink: fix potential deadlock in netlink_set_err()")
Reported-by: syzbot+5da61cf6a9bc1902d422@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=5da61cf6a9bc1902d422
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
include/net/sock.h | 1 +
net/core/sock.c | 11 +++++++++++
net/netlink/diag.c | 2 +-
3 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index 6f428a7f3567..48bda71a8c99 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2101,6 +2101,7 @@ static inline void sock_graft(struct sock *sk, struct socket *parent)
kuid_t sock_i_uid(struct sock *sk);
unsigned long sock_i_ino(struct sock *sk);
+unsigned long sock_i_ino_bh_disabled(struct sock *sk);
static inline kuid_t sock_net_uid(const struct net *net, const struct sock *sk)
{
diff --git a/net/core/sock.c b/net/core/sock.c
index 6e5662ca00fe..99ae761ec592 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2561,6 +2561,17 @@ unsigned long sock_i_ino(struct sock *sk)
}
EXPORT_SYMBOL(sock_i_ino);
+unsigned long sock_i_ino_bh_disabled(struct sock *sk)
+{
+ unsigned long ino;
+
+ read_lock(&sk->sk_callback_lock);
+ ino = sk->sk_socket ? SOCK_INODE(sk->sk_socket)->i_ino : 0;
+ read_unlock(&sk->sk_callback_lock);
+ return ino;
+}
+EXPORT_SYMBOL(sock_i_ino_bh_disabled);
+
/*
* Allocate a skb from the socket's send buffer.
*/
diff --git a/net/netlink/diag.c b/net/netlink/diag.c
index 4143b2ea4195..e11af5514cc9 100644
--- a/net/netlink/diag.c
+++ b/net/netlink/diag.c
@@ -168,7 +168,7 @@ static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq,
NLM_F_MULTI,
- sock_i_ino(sk)) < 0) {
+ sock_i_ino_bh_disabled(sk)) < 0) {
ret = 1;
break;
}
--
2.30.2
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