Patch "Bluetooth: Fix use-after-free bugs caused by sco_sock_timeout" has been added to the 6.1-stable tree

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

    Bluetooth: Fix use-after-free bugs caused by sco_sock_timeout

to the 6.1-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-fix-use-after-free-bugs-caused-by-sco_sock.patch
and it can be found in the queue-6.1 subdirectory.

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



commit f30805c174ebd25e1f311bdd554afaeac4b93d97
Author: Duoming Zhou <duoming@xxxxxxxxxx>
Date:   Thu Apr 25 22:23:45 2024 +0800

    Bluetooth: Fix use-after-free bugs caused by sco_sock_timeout
    
    [ Upstream commit 483bc08181827fc475643272ffb69c533007e546 ]
    
    When the sco connection is established and then, the sco socket
    is releasing, timeout_work will be scheduled to judge whether
    the sco disconnection is timeout. The sock will be deallocated
    later, but it is dereferenced again in sco_sock_timeout. As a
    result, the use-after-free bugs will happen. The root cause is
    shown below:
    
        Cleanup Thread               |      Worker Thread
    sco_sock_release                 |
      sco_sock_close                 |
        __sco_sock_close             |
          sco_sock_set_timer         |
            schedule_delayed_work    |
      sco_sock_kill                  |    (wait a time)
        sock_put(sk) //FREE          |  sco_sock_timeout
                                     |    sock_hold(sk) //USE
    
    The KASAN report triggered by POC is shown below:
    
    [   95.890016] ==================================================================
    [   95.890496] BUG: KASAN: slab-use-after-free in sco_sock_timeout+0x5e/0x1c0
    [   95.890755] Write of size 4 at addr ffff88800c388080 by task kworker/0:0/7
    ...
    [   95.890755] Workqueue: events sco_sock_timeout
    [   95.890755] Call Trace:
    [   95.890755]  <TASK>
    [   95.890755]  dump_stack_lvl+0x45/0x110
    [   95.890755]  print_address_description+0x78/0x390
    [   95.890755]  print_report+0x11b/0x250
    [   95.890755]  ? __virt_addr_valid+0xbe/0xf0
    [   95.890755]  ? sco_sock_timeout+0x5e/0x1c0
    [   95.890755]  kasan_report+0x139/0x170
    [   95.890755]  ? update_load_avg+0xe5/0x9f0
    [   95.890755]  ? sco_sock_timeout+0x5e/0x1c0
    [   95.890755]  kasan_check_range+0x2c3/0x2e0
    [   95.890755]  sco_sock_timeout+0x5e/0x1c0
    [   95.890755]  process_one_work+0x561/0xc50
    [   95.890755]  worker_thread+0xab2/0x13c0
    [   95.890755]  ? pr_cont_work+0x490/0x490
    [   95.890755]  kthread+0x279/0x300
    [   95.890755]  ? pr_cont_work+0x490/0x490
    [   95.890755]  ? kthread_blkcg+0xa0/0xa0
    [   95.890755]  ret_from_fork+0x34/0x60
    [   95.890755]  ? kthread_blkcg+0xa0/0xa0
    [   95.890755]  ret_from_fork_asm+0x11/0x20
    [   95.890755]  </TASK>
    [   95.890755]
    [   95.890755] Allocated by task 506:
    [   95.890755]  kasan_save_track+0x3f/0x70
    [   95.890755]  __kasan_kmalloc+0x86/0x90
    [   95.890755]  __kmalloc+0x17f/0x360
    [   95.890755]  sk_prot_alloc+0xe1/0x1a0
    [   95.890755]  sk_alloc+0x31/0x4e0
    [   95.890755]  bt_sock_alloc+0x2b/0x2a0
    [   95.890755]  sco_sock_create+0xad/0x320
    [   95.890755]  bt_sock_create+0x145/0x320
    [   95.890755]  __sock_create+0x2e1/0x650
    [   95.890755]  __sys_socket+0xd0/0x280
    [   95.890755]  __x64_sys_socket+0x75/0x80
    [   95.890755]  do_syscall_64+0xc4/0x1b0
    [   95.890755]  entry_SYSCALL_64_after_hwframe+0x67/0x6f
    [   95.890755]
    [   95.890755] Freed by task 506:
    [   95.890755]  kasan_save_track+0x3f/0x70
    [   95.890755]  kasan_save_free_info+0x40/0x50
    [   95.890755]  poison_slab_object+0x118/0x180
    [   95.890755]  __kasan_slab_free+0x12/0x30
    [   95.890755]  kfree+0xb2/0x240
    [   95.890755]  __sk_destruct+0x317/0x410
    [   95.890755]  sco_sock_release+0x232/0x280
    [   95.890755]  sock_close+0xb2/0x210
    [   95.890755]  __fput+0x37f/0x770
    [   95.890755]  task_work_run+0x1ae/0x210
    [   95.890755]  get_signal+0xe17/0xf70
    [   95.890755]  arch_do_signal_or_restart+0x3f/0x520
    [   95.890755]  syscall_exit_to_user_mode+0x55/0x120
    [   95.890755]  do_syscall_64+0xd1/0x1b0
    [   95.890755]  entry_SYSCALL_64_after_hwframe+0x67/0x6f
    [   95.890755]
    [   95.890755] The buggy address belongs to the object at ffff88800c388000
    [   95.890755]  which belongs to the cache kmalloc-1k of size 1024
    [   95.890755] The buggy address is located 128 bytes inside of
    [   95.890755]  freed 1024-byte region [ffff88800c388000, ffff88800c388400)
    [   95.890755]
    [   95.890755] The buggy address belongs to the physical page:
    [   95.890755] page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88800c38a800 pfn:0xc388
    [   95.890755] head: order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
    [   95.890755] anon flags: 0x100000000000840(slab|head|node=0|zone=1)
    [   95.890755] page_type: 0xffffffff()
    [   95.890755] raw: 0100000000000840 ffff888006842dc0 0000000000000000 0000000000000001
    [   95.890755] raw: ffff88800c38a800 000000000010000a 00000001ffffffff 0000000000000000
    [   95.890755] head: 0100000000000840 ffff888006842dc0 0000000000000000 0000000000000001
    [   95.890755] head: ffff88800c38a800 000000000010000a 00000001ffffffff 0000000000000000
    [   95.890755] head: 0100000000000003 ffffea000030e201 ffffea000030e248 00000000ffffffff
    [   95.890755] head: 0000000800000000 0000000000000000 00000000ffffffff 0000000000000000
    [   95.890755] page dumped because: kasan: bad access detected
    [   95.890755]
    [   95.890755] Memory state around the buggy address:
    [   95.890755]  ffff88800c387f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
    [   95.890755]  ffff88800c388000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    [   95.890755] >ffff88800c388080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    [   95.890755]                    ^
    [   95.890755]  ffff88800c388100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    [   95.890755]  ffff88800c388180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    [   95.890755] ==================================================================
    
    Fix this problem by adding a check protected by sco_conn_lock to judget
    whether the conn->hcon is null. Because the conn->hcon will be set to null,
    when the sock is releasing.
    
    Fixes: ba316be1b6a0 ("Bluetooth: schedule SCO timeouts with delayed_work")
    Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx>
    Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index 4a6bf60f3e7aa..301cf802d32c4 100644
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -84,6 +84,10 @@ static void sco_sock_timeout(struct work_struct *work)
 	struct sock *sk;
 
 	sco_conn_lock(conn);
+	if (!conn->hcon) {
+		sco_conn_unlock(conn);
+		return;
+	}
 	sk = conn->sk;
 	if (sk)
 		sock_hold(sk);




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