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    Subject[PATCH 5.12 037/363] Bluetooth: check for zapped sk before connecting
    Date
    From: Archie Pusaka <apusaka@chromium.org>

    [ 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@chromium.org>
    Reported-by: syzbot+abfc0f5e668d4099af73@syzkaller.appspotmail.com
    Reviewed-by: Alain Michaud <alainm@chromium.org>
    Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
    Reviewed-by: Guenter Roeck <groeck@chromium.org>
    Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/bluetooth/l2cap_sock.c | 8 ++++++++
    1 file changed, 8 insertions(+)

    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;
    --
    2.30.2


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