Patch "Bluetooth: check for zapped sk before connecting" has been added to the 5.12-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    Bluetooth: check for zapped sk before connecting

to the 5.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     bluetooth-check-for-zapped-sk-before-connecting.patch
and it can be found in the queue-5.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit c93169d8f271e727938395d71e15a91a36d812e3
Author: Archie Pusaka <apusaka@xxxxxxxxxxxx>
Date:   Tue Mar 23 16:32:20 2021 +0800

    Bluetooth: check for zapped sk before connecting
    
    [ Upstream commit 3af70b39fa2d415dc86c370e5b24ddb9fdacbd6f ]
    
    There is a possibility of receiving a zapped sock on
    l2cap_sock_connect(). This could lead to interesting crashes, one
    such case is tearing down an already tore l2cap_sock as is happened
    with this call trace:
    
    __dump_stack lib/dump_stack.c:15 [inline]
    dump_stack+0xc4/0x118 lib/dump_stack.c:56
    register_lock_class kernel/locking/lockdep.c:792 [inline]
    register_lock_class+0x239/0x6f6 kernel/locking/lockdep.c:742
    __lock_acquire+0x209/0x1e27 kernel/locking/lockdep.c:3105
    lock_acquire+0x29c/0x2fb kernel/locking/lockdep.c:3599
    __raw_spin_lock_bh include/linux/spinlock_api_smp.h:137 [inline]
    _raw_spin_lock_bh+0x38/0x47 kernel/locking/spinlock.c:175
    spin_lock_bh include/linux/spinlock.h:307 [inline]
    lock_sock_nested+0x44/0xfa net/core/sock.c:2518
    l2cap_sock_teardown_cb+0x88/0x2fb net/bluetooth/l2cap_sock.c:1345
    l2cap_chan_del+0xa3/0x383 net/bluetooth/l2cap_core.c:598
    l2cap_chan_close+0x537/0x5dd net/bluetooth/l2cap_core.c:756
    l2cap_chan_timeout+0x104/0x17e net/bluetooth/l2cap_core.c:429
    process_one_work+0x7e3/0xcb0 kernel/workqueue.c:2064
    worker_thread+0x5a5/0x773 kernel/workqueue.c:2196
    kthread+0x291/0x2a6 kernel/kthread.c:211
    ret_from_fork+0x4e/0x80 arch/x86/entry/entry_64.S:604
    
    Signed-off-by: Archie Pusaka <apusaka@xxxxxxxxxxxx>
    Reported-by: syzbot+abfc0f5e668d4099af73@xxxxxxxxxxxxxxxxxxxxxxxxx
    Reviewed-by: Alain Michaud <alainm@xxxxxxxxxxxx>
    Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>
    Reviewed-by: Guenter Roeck <groeck@xxxxxxxxxxxx>
    Signed-off-by: Marcel Holtmann <marcel@xxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index f1b1edd0b697..c99d65ef13b1 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -179,9 +179,17 @@ static int l2cap_sock_connect(struct socket *sock, struct sockaddr *addr,
 	struct l2cap_chan *chan = l2cap_pi(sk)->chan;
 	struct sockaddr_l2 la;
 	int len, err = 0;
+	bool zapped;
 
 	BT_DBG("sk %p", sk);
 
+	lock_sock(sk);
+	zapped = sock_flag(sk, SOCK_ZAPPED);
+	release_sock(sk);
+
+	if (zapped)
+		return -EINVAL;
+
 	if (!addr || alen < offsetofend(struct sockaddr, sa_family) ||
 	    addr->sa_family != AF_BLUETOOTH)
 		return -EINVAL;