netdev - [PATCH] net: nfc: fix panic in accept()

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Message-ID: <1340639612.10893.84.camel@edumazet-glaptop>
Date:	Mon, 25 Jun 2012 17:53:32 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Sasha Levin <levinsasha928@...il.com>
Cc:	Dave Jones <davej@...hat.com>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	David Miller <davem@...emloft.net>,
	lauro.venancio@...nbossa.org, aloisio.almeida@...nbossa.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	linux-wireless <linux-wireless@...r.kernel.org>
Subject: [PATCH] net: nfc: fix panic in accept()

From: Eric Dumazet <edumazet@...gle.com>

Sasha Levin reported following panic :

[ 2136.383310] BUG: unable to handle kernel NULL pointer dereference at
00000000000003b0
[ 2136.384022] IP: [<ffffffff8114e400>] __lock_acquire+0xc0/0x4b0
[ 2136.384022] PGD 131c4067 PUD 11c0c067 PMD 0 
[ 2136.388106] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
[ 2136.388106] CPU 1 
[ 2136.388106] Pid: 24855, comm: trinity-child1 Tainted: G        W
3.5.0-rc2-sasha-00015-g7b268f7 #374  
[ 2136.388106] RIP: 0010:[<ffffffff8114e400>]  [<ffffffff8114e400>]
__lock_acquire+0xc0/0x4b0
[ 2136.388106] RSP: 0018:ffff8800130b3ca8  EFLAGS: 00010046
[ 2136.388106] RAX: 0000000000000086 RBX: ffff88001186b000 RCX:
0000000000000000
[ 2136.388106] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
0000000000000000
[ 2136.388106] RBP: ffff8800130b3d08 R08: 0000000000000001 R09:
0000000000000000
[ 2136.388106] R10: 0000000000000000 R11: 0000000000000001 R12:
0000000000000002
[ 2136.388106] R13: 00000000000003b0 R14: 0000000000000000 R15:
0000000000000000
[ 2136.388106] FS:  00007fa5b1bd4700(0000) GS:ffff88001b800000(0000)
knlGS:0000000000000000
[ 2136.388106] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2136.388106] CR2: 00000000000003b0 CR3: 0000000011d1f000 CR4:
00000000000406e0
[ 2136.388106] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[ 2136.388106] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
0000000000000400
[ 2136.388106] Process trinity-child1 (pid: 24855, threadinfo
ffff8800130b2000, task ffff88001186b000)
[ 2136.388106] Stack:
[ 2136.388106]  ffff8800130b3cd8 ffffffff81121785 ffffffff81236774
000080d000000001
[ 2136.388106]  ffff88001b9d6c00 00000000001d6c00 ffffffff130b3d08
ffff88001186b000
[ 2136.388106]  0000000000000000 0000000000000002 0000000000000000
0000000000000000
[ 2136.388106] Call Trace:
[ 2136.388106]  [<ffffffff81121785>] ? sched_clock_local+0x25/0x90
[ 2136.388106]  [<ffffffff81236774>] ? get_empty_filp+0x74/0x220
[ 2136.388106]  [<ffffffff8114e97a>] lock_acquire+0x18a/0x1e0
[ 2136.388106]  [<ffffffff836b37df>] ? rawsock_release+0x4f/0xa0
[ 2136.388106]  [<ffffffff837c0ef0>] _raw_write_lock_bh+0x40/0x80
[ 2136.388106]  [<ffffffff836b37df>] ? rawsock_release+0x4f/0xa0
[ 2136.388106]  [<ffffffff836b37df>] rawsock_release+0x4f/0xa0
[ 2136.388106]  [<ffffffff8321cfe8>] sock_release+0x18/0x70
[ 2136.388106]  [<ffffffff8321d069>] sock_close+0x29/0x30
[ 2136.388106]  [<ffffffff81236bca>] __fput+0x11a/0x2c0
[ 2136.388106]  [<ffffffff81236d85>] fput+0x15/0x20
[ 2136.388106]  [<ffffffff8321de34>] sys_accept4+0x1b4/0x200
[ 2136.388106]  [<ffffffff837c165c>] ? _raw_spin_unlock_irq+0x4c/0x80
[ 2136.388106]  [<ffffffff837c1669>] ? _raw_spin_unlock_irq+0x59/0x80
[ 2136.388106]  [<ffffffff837c2565>] ? sysret_check+0x22/0x5d
[ 2136.388106]  [<ffffffff8321de8b>] sys_accept+0xb/0x10
[ 2136.388106]  [<ffffffff837c2539>] system_call_fastpath+0x16/0x1b
[ 2136.388106] Code: ec 04 00 0f 85 ea 03 00 00 be d5 0b 00 00 48 c7 c7
8a c1 40 84 e8 b1 a5 f8 ff 31 c0 e9 d4 03 00 00 66 2e 0f 1f 84 00 00 00
00 00 <49> 81 7d 00 60 73 5e 85 b8 01 00 00 00 44 0f 44 e0 83 fe 01 77 
[ 2136.388106] RIP  [<ffffffff8114e400>] __lock_acquire+0xc0/0x4b0
[ 2136.388106]  RSP <ffff8800130b3ca8>
[ 2136.388106] CR2: 00000000000003b0
[ 2136.388106] ---[ end trace 6d450e935ee18982 ]---
[ 2136.388106] Kernel panic - not syncing: Fatal exception in interrupt

rawsock_release() should test if sock->sk is NULL before calling
sock_orphan()/sock_put()

Reported-by: Sasha Levin <levinsasha928@...il.com>
Tested-by: Sasha Levin <levinsasha928@...il.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Samuel Ortiz <sameo@...ux.intel.com>
---
 net/nfc/rawsock.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/nfc/rawsock.c b/net/nfc/rawsock.c
index ec1134c..208416e 100644
--- a/net/nfc/rawsock.c
+++ b/net/nfc/rawsock.c
@@ -54,11 +54,12 @@ static int rawsock_release(struct socket *sock)
 {
 	struct sock *sk = sock->sk;
 
-	pr_debug("sock=%p\n", sock);
-
-	sock_orphan(sk);
-	sock_put(sk);
+	pr_debug("sock=%p sk=%p\n", sock, sk);
 
+	if (sk) {
+		sock_orphan(sk);
+		sock_put(sk);
+	}
 	return 0;
 }
 


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