diff mbox series

Bluetooth: L2CAP: Fix use-after-free

Message ID 20230202090509.2774062-1-iam@sung-woo.kim
State New
Headers
Series Bluetooth: L2CAP: Fix use-after-free |

Commit Message

Sungwoo Kim Feb. 2, 2023, 9:05 a.m. UTC 
  Due to the race condition between l2cap_sock_cleanup_listen and
l2cap_sock_close_cb, l2cap_sock_kill can receive already freed sk,
resulting in use-after-free inside l2cap_sock_kill.
This patch prevent this by adding a null check in l2cap_sock_kill.

Context 1:
l2cap_sock_cleanup_listen();
  // context switched
  l2cap_chan_lock(chan);
  l2cap_sock_kill(sk); // <-- sk is already freed below

Context 2:
l2cap_chan_timeout();
  l2cap_chan_lock(chan);
  chan->ops->close(chan);
    l2cap_sock_close_cb()
    l2cap_sock_kill(sk); // <-- sk is freed here
  l2cap_chan_unlock(chan);

Signed-off-by: Sungwoo Kim <iam@sung-woo.kim>
---
 net/bluetooth/l2cap_sock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Eric Dumazet Feb. 2, 2023, 9:26 a.m. UTC | #1 
On Thu, Feb 2, 2023 at 10:07 AM Sungwoo Kim <iam@sung-woo.kim> wrote:
>
> Due to the race condition between l2cap_sock_cleanup_listen and
> l2cap_sock_close_cb, l2cap_sock_kill can receive already freed sk,
> resulting in use-after-free inside l2cap_sock_kill.
> This patch prevent this by adding a null check in l2cap_sock_kill.
>
> Context 1:
> l2cap_sock_cleanup_listen();
>   // context switched
>   l2cap_chan_lock(chan);
>   l2cap_sock_kill(sk); // <-- sk is already freed below

But sk is used in l2cap_sock_cleanup_listen()
and should not be NULL...

while ((sk = bt_accept_dequeue(parent, NULL))) {
  ...
  l2cap_sock_kill(sk);
  ..
}

It would help if you send us a stack trace ...

>
> Context 2:
> l2cap_chan_timeout();
>   l2cap_chan_lock(chan);
>   chan->ops->close(chan);
>     l2cap_sock_close_cb()
>     l2cap_sock_kill(sk); // <-- sk is freed here
>   l2cap_chan_unlock(chan);
>

Please add a Fixes: tag

> Signed-off-by: Sungwoo Kim <iam@sung-woo.kim>
> ---
>  net/bluetooth/l2cap_sock.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
> index ca8f07f35..657704059 100644
> --- a/net/bluetooth/l2cap_sock.c
> +++ b/net/bluetooth/l2cap_sock.c
> @@ -1245,7 +1245,7 @@ static int l2cap_sock_recvmsg(struct socket *sock, struct msghdr *msg,
>   */
>  static void l2cap_sock_kill(struct sock *sk)
>  {
> -       if (!sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket)
> +       if (!sk || !sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket)
>                 return;
>
>         BT_DBG("sk %p state %s", sk, state_to_string(sk->sk_state));
> --
> 2.25.1
>
Sungwoo Kim Feb. 2, 2023, 12:09 p.m. UTC | #2 
On Thu, Feb 2, 2023 at 4:26 AM Eric Dumazet <edumazet@google.com> wrote:
>
> On Thu, Feb 2, 2023 at 10:07 AM Sungwoo Kim <iam@sung-woo.kim> wrote:
> >
> > Due to the race condition between l2cap_sock_cleanup_listen and
> > l2cap_sock_close_cb, l2cap_sock_kill can receive already freed sk,
> > resulting in use-after-free inside l2cap_sock_kill.
> > This patch prevent this by adding a null check in l2cap_sock_kill.
> >
> > Context 1:
> > l2cap_sock_cleanup_listen();
> >   // context switched
> >   l2cap_chan_lock(chan);
> >   l2cap_sock_kill(sk); // <-- sk is already freed below
>
> But sk is used in l2cap_sock_cleanup_listen()
> and should not be NULL...
>
> while ((sk = bt_accept_dequeue(parent, NULL))) {
>   ...
>   l2cap_sock_kill(sk);
>   ..
> }
>
> It would help if you send us a stack trace ...

Here is the stack trace and l2cap_sock.c:
https://gist.github.com/swkim101/5c3b8cb7c7d7172aef23810c9412f323

==================================================================
BUG: KASAN: use-after-free in l2cap_sock_kill (/v6.1-rc2/./include/net/sock.h:986 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1281) 
Read of size 8 at addr ffff88800f7f4060 by task l2cap-server/1764
CPU: 0 PID: 1764 Comm: l2cap-server Not tainted 6.1.0-rc2 #129
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
 <TASK>
dump_stack_lvl (/v6.1-rc2/lib/dump_stack.c:105) 
print_address_description+0x7e/0x360 
print_report (/v6.1-rc2/mm/kasan/report.c:187 /v6.1-rc2/mm/kasan/report.c:389) 
? __virt_addr_valid (/v6.1-rc2/./include/linux/mmzone.h:1855 /v6.1-rc2/arch/x86/mm/physaddr.c:65) 
? kasan_complete_mode_report_info (/v6.1-rc2/mm/kasan/report_generic.c:104 /v6.1-rc2/mm/kasan/report_generic.c:127 /v6.1-rc2/mm/kasan/report_generic.c:136) 
? l2cap_sock_kill (/v6.1-rc2/./include/net/sock.h:986 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1281) 
kasan_report (/v6.1-rc2/mm/kasan/report.c:? /v6.1-rc2/mm/kasan/report.c:484) 
? l2cap_sock_kill (/v6.1-rc2/./include/net/sock.h:986 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1281) 
kasan_check_range (/v6.1-rc2/mm/kasan/generic.c:85 /v6.1-rc2/mm/kasan/generic.c:115 /v6.1-rc2/mm/kasan/generic.c:128 /v6.1-rc2/mm/kasan/generic.c:159 /v6.1-rc2/mm/kasan/generic.c:180 /v6.1-rc2/mm/kasan/generic.c:189) 
__kasan_check_read (/v6.1-rc2/mm/kasan/shadow.c:31) 
l2cap_sock_kill (/v6.1-rc2/./include/net/sock.h:986 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1281) 
l2cap_sock_teardown_cb (/v6.1-rc2/./include/net/bluetooth/bluetooth.h:304 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1475 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1612) 
l2cap_chan_close (/v6.1-rc2/net/bluetooth/l2cap_core.c:885) 
? __kasan_check_write (/v6.1-rc2/mm/kasan/shadow.c:37) 
l2cap_sock_shutdown (/v6.1-rc2/./include/linux/kcsan-checks.h:231 /v6.1-rc2/./include/net/sock.h:2470 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1321 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1377) 
? _raw_write_unlock (/v6.1-rc2/./include/asm-generic/qrwlock.h:122 /v6.1-rc2/./include/linux/rwlock_api_smp.h:225 /v6.1-rc2/kernel/locking/spinlock.c:342) 
l2cap_sock_release (/v6.1-rc2/net/bluetooth/l2cap_sock.c:1453) 
sock_close (/v6.1-rc2/net/socket.c:1382) 
? sock_mmap (/v6.1-rc2/net/socket.c:?) 
__fput (/v6.1-rc2/./include/linux/fsnotify.h:? /v6.1-rc2/./include/linux/fsnotify.h:99 /v6.1-rc2/./include/linux/fsnotify.h:341 /v6.1-rc2/fs/file_table.c:306) 
____fput (/v6.1-rc2/fs/file_table.c:348) 
task_work_run (/v6.1-rc2/kernel/task_work.c:165) 
do_exit (/v6.1-rc2/kernel/exit.c:?) 
do_group_exit (/v6.1-rc2/kernel/exit.c:943) 
? __kasan_check_write (/v6.1-rc2/mm/kasan/shadow.c:37) 
get_signal (/v6.1-rc2/kernel/signal.c:2863) 
? _raw_spin_unlock (/v6.1-rc2/./include/linux/spinlock_api_smp.h:142 /v6.1-rc2/kernel/locking/spinlock.c:186) 
? finish_task_switch (/v6.1-rc2/./arch/x86/include/asm/current.h:15 /v6.1-rc2/kernel/sched/core.c:5065) 
arch_do_signal_or_restart (/v6.1-rc2/arch/x86/kernel/signal.c:869) 
exit_to_user_mode_prepare (/v6.1-rc2/kernel/entry/common.c:383) 
syscall_exit_to_user_mode (/v6.1-rc2/./arch/x86/include/asm/current.h:15 /v6.1-rc2/kernel/entry/common.c:261 /v6.1-rc2/kernel/entry/common.c:283 /v6.1-rc2/kernel/entry/common.c:296) 
do_syscall_64 (/v6.1-rc2/arch/x86/entry/common.c:50 /v6.1-rc2/arch/x86/entry/common.c:80) 
? sysvec_apic_timer_interrupt (/v6.1-rc2/arch/x86/kernel/apic/apic.c:1107) 
entry_SYSCALL_64_after_hwframe (/v6.1-rc2/arch/x86/entry/entry_64.S:120) 
RIP: 0033:0x7f66c14db970
Code: Unable to access opcode bytes at 0x7f66c14db946.

Code starting with the faulting instruction
===========================================
RSP: 002b:00007ffe166a5508 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: 0000000000000013 RBX: 0000000000000013 RCX: 00007f66c14db970
RDX: 0000000000000013 RSI: 00007ffe166a56d0 RDI: 0000000000000002
RBP: 00007ffe166a56d0 R08: 00007f66c1a28440 R09: 0000000000000013
R10: 0000000000000078 R11: 0000000000000246 R12: 0000000000000013
R13: 0000000000000001 R14: 00007f66c179a520 R15: 0000000000000013
 </TASK>
Allocated by task 77:
kasan_set_track (/v6.1-rc2/mm/kasan/common.c:51) 
kasan_save_alloc_info (/v6.1-rc2/mm/kasan/generic.c:432 /v6.1-rc2/mm/kasan/generic.c:498) 
__kasan_kmalloc (/v6.1-rc2/mm/kasan/common.c:356) 
__kmalloc (/v6.1-rc2/mm/slab_common.c:943 /v6.1-rc2/mm/slab_common.c:968) 
sk_prot_alloc (/v6.1-rc2/net/core/sock.c:2028) 
sk_alloc (/v6.1-rc2/net/core/sock.c:2083) 
l2cap_sock_alloc (/v6.1-rc2/net/bluetooth/l2cap_sock.c:1903) 
l2cap_sock_new_connection_cb (/v6.1-rc2/net/bluetooth/l2cap_sock.c:1504) 
l2cap_connect (/v6.1-rc2/net/bluetooth/l2cap_core.c:102 /v6.1-rc2/net/bluetooth/l2cap_core.c:4277) 
l2cap_bredr_sig_cmd (/v6.1-rc2/net/bluetooth/l2cap_core.c:5634 /v6.1-rc2/net/bluetooth/l2cap_core.c:5927) 
l2cap_recv_frame (/v6.1-rc2/net/bluetooth/l2cap_core.c:7851 /v6.1-rc2/net/bluetooth/l2cap_core.c:7919) 
l2cap_recv_acldata (/v6.1-rc2/net/bluetooth/l2cap_core.c:8601 /v6.1-rc2/net/bluetooth/l2cap_core.c:8631) 
hci_rx_work (/v6.1-rc2/./include/net/bluetooth/hci_core.h:1121 /v6.1-rc2/net/bluetooth/hci_core.c:3937 /v6.1-rc2/net/bluetooth/hci_core.c:4189) 
process_one_work (/v6.1-rc2/kernel/workqueue.c:2225) 
worker_thread (/v6.1-rc2/kernel/workqueue.c:816 /v6.1-rc2/kernel/workqueue.c:2107 /v6.1-rc2/kernel/workqueue.c:2159 /v6.1-rc2/kernel/workqueue.c:2408) 
kthread (/v6.1-rc2/kernel/kthread.c:361) 
ret_from_fork (/v6.1-rc2/arch/x86/entry/entry_64.S:306) 
Freed by task 52:
kasan_set_track (/v6.1-rc2/mm/kasan/common.c:51) 
kasan_save_free_info (/v6.1-rc2/mm/kasan/generic.c:508) 
____kasan_slab_free (/v6.1-rc2/./include/linux/slub_def.h:164 /v6.1-rc2/mm/kasan/common.c:214) 
__kasan_slab_free (/v6.1-rc2/mm/kasan/common.c:244) 
slab_free_freelist_hook (/v6.1-rc2/mm/slub.c:381 /v6.1-rc2/mm/slub.c:1747) 
__kmem_cache_free (/v6.1-rc2/mm/slub.c:3656 /v6.1-rc2/mm/slub.c:3674) 
kfree (/v6.1-rc2/mm/slab_common.c:1007) 
__sk_destruct (/v6.1-rc2/./include/linux/cred.h:288 /v6.1-rc2/net/core/sock.c:2147) 
__sk_free (/v6.1-rc2/./include/linux/sock_diag.h:87 /v6.1-rc2/net/core/sock.c:2175) 
sk_free (/v6.1-rc2/./include/linux/instrumented.h:? /v6.1-rc2/./include/linux/atomic/atomic-instrumented.h:176 /v6.1-rc2/./include/linux/refcount.h:272 /v6.1-rc2/./include/linux/refcount.h:315 /v6.1-rc2/./include/linux/refcount.h:333 /v6.1-rc2/net/core/sock.c:2188) 
l2cap_sock_kill (/v6.1-rc2/./include/net/bluetooth/bluetooth.h:286 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1284) 
l2cap_sock_close_cb (/v6.1-rc2/net/bluetooth/l2cap_sock.c:1576) 
l2cap_chan_timeout (/v6.1-rc2/./include/net/bluetooth/bluetooth.h:296 /v6.1-rc2/net/bluetooth/l2cap_core.c:462) 
process_one_work (/v6.1-rc2/kernel/workqueue.c:2225) 
worker_thread (/v6.1-rc2/kernel/workqueue.c:816 /v6.1-rc2/kernel/workqueue.c:2107 /v6.1-rc2/kernel/workqueue.c:2159 /v6.1-rc2/kernel/workqueue.c:2408) 
kthread (/v6.1-rc2/kernel/kthread.c:361) 
ret_from_fork (/v6.1-rc2/arch/x86/entry/entry_64.S:306) 
The buggy address belongs to the object at ffff88800f7f4000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 96 bytes inside of
 1024-byte region [ffff88800f7f4000, ffff88800f7f4400)
The buggy address belongs to the physical page:
page:00000000b8d65c1d refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88800f7f6800 pfn:0xf7f4
head:00000000b8d65c1d order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfffffc0010200(slab|head|node=0|zone=1|lastcpupid=0x1fffff)
raw: 000fffffc0010200 ffffea0000993408 ffffea0000991308 ffff888005841dc0
raw: ffff88800f7f6800 0000000000080002 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
 ffff88800f7f3f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88800f7f3f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88800f7f4000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff88800f7f4080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88800f7f4100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

> >
> > Context 2:
> > l2cap_chan_timeout();
> >   l2cap_chan_lock(chan);
> >   chan->ops->close(chan);
> >     l2cap_sock_close_cb()
> >     l2cap_sock_kill(sk); // <-- sk is freed here
> >   l2cap_chan_unlock(chan);
> >
>
> Please add a Fixes: tag

Fixes: 6c08fc896b60 ("Bluetooth: Fix refcount use-after-free issue")
> > Signed-off-by: Sungwoo Kim <iam@sung-woo.kim>
> > ---
> >  net/bluetooth/l2cap_sock.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
> > index ca8f07f35..657704059 100644
> > --- a/net/bluetooth/l2cap_sock.c
> > +++ b/net/bluetooth/l2cap_sock.c
> > @@ -1245,7 +1245,7 @@ static int l2cap_sock_recvmsg(struct socket *sock, struct msghdr *msg,
> >   */
> >  static void l2cap_sock_kill(struct sock *sk)
> >  {
> > -       if (!sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket)
> > +       if (!sk || !sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket)
> >                 return;
> >
> >         BT_DBG("sk %p state %s", sk, state_to_string(sk->sk_state));
> > --
> > 2.25.1
> >
Eric Dumazet Feb. 2, 2023, 12:35 p.m. UTC | #3 
On Thu, Feb 2, 2023 at 1:09 PM Sungwoo Kim <iam@sung-woo.kim> wrote:
>
> On Thu, Feb 2, 2023 at 4:26 AM Eric Dumazet <edumazet@google.com> wrote:
> >
> > On Thu, Feb 2, 2023 at 10:07 AM Sungwoo Kim <iam@sung-woo.kim> wrote:
> > >
> > > Due to the race condition between l2cap_sock_cleanup_listen and
> > > l2cap_sock_close_cb, l2cap_sock_kill can receive already freed sk,
> > > resulting in use-after-free inside l2cap_sock_kill.
> > > This patch prevent this by adding a null check in l2cap_sock_kill.
> > >
> > > Context 1:
> > > l2cap_sock_cleanup_listen();
> > >   // context switched
> > >   l2cap_chan_lock(chan);
> > >   l2cap_sock_kill(sk); // <-- sk is already freed below
> >
> > But sk is used in l2cap_sock_cleanup_listen()
> > and should not be NULL...
> >
> > while ((sk = bt_accept_dequeue(parent, NULL))) {
> >   ...
> >   l2cap_sock_kill(sk);
> >   ..
> > }
> >
> > It would help if you send us a stack trace ...
>
> Here is the stack trace and l2cap_sock.c:
> https://gist.github.com/swkim101/5c3b8cb7c7d7172aef23810c9412f323
>
> ==================================================================
> BUG: KASAN: use-after-free in l2cap_sock_kill (/v6.1-rc2/./include/net/sock.h:986 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1281)
> Read of size 8 at addr ffff88800f7f4060 by task l2cap-server/1764
> CPU: 0 PID: 1764 Comm: l2cap-server Not tainted 6.1.0-rc2 #129
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
> Call Trace:
>  <TASK>
> dump_stack_lvl (/v6.1-rc2/lib/dump_stack.c:105)
> print_address_description+0x7e/0x360
> print_report (/v6.1-rc2/mm/kasan/report.c:187 /v6.1-rc2/mm/kasan/report.c:389)
> ? __virt_addr_valid (/v6.1-rc2/./include/linux/mmzone.h:1855 /v6.1-rc2/arch/x86/mm/physaddr.c:65)
> ? kasan_complete_mode_report_info (/v6.1-rc2/mm/kasan/report_generic.c:104 /v6.1-rc2/mm/kasan/report_generic.c:127 /v6.1-rc2/mm/kasan/report_generic.c:136)
> ? l2cap_sock_kill (/v6.1-rc2/./include/net/sock.h:986 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1281)
> kasan_report (/v6.1-rc2/mm/kasan/report.c:? /v6.1-rc2/mm/kasan/report.c:484)
> ? l2cap_sock_kill (/v6.1-rc2/./include/net/sock.h:986 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1281)
> kasan_check_range (/v6.1-rc2/mm/kasan/generic.c:85 /v6.1-rc2/mm/kasan/generic.c:115 /v6.1-rc2/mm/kasan/generic.c:128 /v6.1-rc2/mm/kasan/generic.c:159 /v6.1-rc2/mm/kasan/generic.c:180 /v6.1-rc2/mm/kasan/generic.c:189)
> __kasan_check_read (/v6.1-rc2/mm/kasan/shadow.c:31)
> l2cap_sock_kill (/v6.1-rc2/./include/net/sock.h:986 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1281)
> l2cap_sock_teardown_cb (/v6.1-rc2/./include/net/bluetooth/bluetooth.h:304 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1475 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1612)
> l2cap_chan_close (/v6.1-rc2/net/bluetooth/l2cap_core.c:885)
> ? __kasan_check_write (/v6.1-rc2/mm/kasan/shadow.c:37)
> l2cap_sock_shutdown (/v6.1-rc2/./include/linux/kcsan-checks.h:231 /v6.1-rc2/./include/net/sock.h:2470 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1321 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1377)
> ? _raw_write_unlock (/v6.1-rc2/./include/asm-generic/qrwlock.h:122 /v6.1-rc2/./include/linux/rwlock_api_smp.h:225 /v6.1-rc2/kernel/locking/spinlock.c:342)
> l2cap_sock_release (/v6.1-rc2/net/bluetooth/l2cap_sock.c:1453)
> sock_close (/v6.1-rc2/net/socket.c:1382)
> ? sock_mmap (/v6.1-rc2/net/socket.c:?)
> __fput (/v6.1-rc2/./include/linux/fsnotify.h:? /v6.1-rc2/./include/linux/fsnotify.h:99 /v6.1-rc2/./include/linux/fsnotify.h:341 /v6.1-rc2/fs/file_table.c:306)
> ____fput (/v6.1-rc2/fs/file_table.c:348)
> task_work_run (/v6.1-rc2/kernel/task_work.c:165)
> do_exit (/v6.1-rc2/kernel/exit.c:?)
> do_group_exit (/v6.1-rc2/kernel/exit.c:943)

OK, now compare this trace with what you put in your changelog...

Very different problem.

Context 1:
l2cap_sock_cleanup_listen();
  // context switched
  l2cap_chan_lock(chan);
  l2cap_sock_kill(sk); // <-- sk is already freed below


On current linux tree, all l2cap_sock_kill() callers already checked sk != NULL

Do you have a repro ?

> ? __kasan_check_write (/v6.1-rc2/mm/kasan/shadow.c:37)
> get_signal (/v6.1-rc2/kernel/signal.c:2863)
> ? _raw_spin_unlock (/v6.1-rc2/./include/linux/spinlock_api_smp.h:142 /v6.1-rc2/kernel/locking/spinlock.c:186)
> ? finish_task_switch (/v6.1-rc2/./arch/x86/include/asm/current.h:15 /v6.1-rc2/kernel/sched/core.c:5065)
> arch_do_signal_or_restart (/v6.1-rc2/arch/x86/kernel/signal.c:869)
> exit_to_user_mode_prepare (/v6.1-rc2/kernel/entry/common.c:383)
> syscall_exit_to_user_mode (/v6.1-rc2/./arch/x86/include/asm/current.h:15 /v6.1-rc2/kernel/entry/common.c:261 /v6.1-rc2/kernel/entry/common.c:283 /v6.1-rc2/kernel/entry/common.c:296)
> do_syscall_64 (/v6.1-rc2/arch/x86/entry/common.c:50 /v6.1-rc2/arch/x86/entry/common.c:80)
> ? sysvec_apic_timer_interrupt (/v6.1-rc2/arch/x86/kernel/apic/apic.c:1107)
> entry_SYSCALL_64_after_hwframe (/v6.1-rc2/arch/x86/entry/entry_64.S:120)
> RIP: 0033:0x7f66c14db970
> Code: Unable to access opcode bytes at 0x7f66c14db946.
>
> Code starting with the faulting instruction
> ===========================================
> RSP: 002b:00007ffe166a5508 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: 0000000000000013 RBX: 0000000000000013 RCX: 00007f66c14db970
> RDX: 0000000000000013 RSI: 00007ffe166a56d0 RDI: 0000000000000002
> RBP: 00007ffe166a56d0 R08: 00007f66c1a28440 R09: 0000000000000013
> R10: 0000000000000078 R11: 0000000000000246 R12: 0000000000000013
> R13: 0000000000000001 R14: 00007f66c179a520 R15: 0000000000000013
>  </TASK>
> Allocated by task 77:
> kasan_set_track (/v6.1-rc2/mm/kasan/common.c:51)
> kasan_save_alloc_info (/v6.1-rc2/mm/kasan/generic.c:432 /v6.1-rc2/mm/kasan/generic.c:498)
> __kasan_kmalloc (/v6.1-rc2/mm/kasan/common.c:356)
> __kmalloc (/v6.1-rc2/mm/slab_common.c:943 /v6.1-rc2/mm/slab_common.c:968)
> sk_prot_alloc (/v6.1-rc2/net/core/sock.c:2028)
> sk_alloc (/v6.1-rc2/net/core/sock.c:2083)
> l2cap_sock_alloc (/v6.1-rc2/net/bluetooth/l2cap_sock.c:1903)
> l2cap_sock_new_connection_cb (/v6.1-rc2/net/bluetooth/l2cap_sock.c:1504)
> l2cap_connect (/v6.1-rc2/net/bluetooth/l2cap_core.c:102 /v6.1-rc2/net/bluetooth/l2cap_core.c:4277)
> l2cap_bredr_sig_cmd (/v6.1-rc2/net/bluetooth/l2cap_core.c:5634 /v6.1-rc2/net/bluetooth/l2cap_core.c:5927)
> l2cap_recv_frame (/v6.1-rc2/net/bluetooth/l2cap_core.c:7851 /v6.1-rc2/net/bluetooth/l2cap_core.c:7919)
> l2cap_recv_acldata (/v6.1-rc2/net/bluetooth/l2cap_core.c:8601 /v6.1-rc2/net/bluetooth/l2cap_core.c:8631)
> hci_rx_work (/v6.1-rc2/./include/net/bluetooth/hci_core.h:1121 /v6.1-rc2/net/bluetooth/hci_core.c:3937 /v6.1-rc2/net/bluetooth/hci_core.c:4189)
> process_one_work (/v6.1-rc2/kernel/workqueue.c:2225)
> worker_thread (/v6.1-rc2/kernel/workqueue.c:816 /v6.1-rc2/kernel/workqueue.c:2107 /v6.1-rc2/kernel/workqueue.c:2159 /v6.1-rc2/kernel/workqueue.c:2408)
> kthread (/v6.1-rc2/kernel/kthread.c:361)
> ret_from_fork (/v6.1-rc2/arch/x86/entry/entry_64.S:306)
> Freed by task 52:
> kasan_set_track (/v6.1-rc2/mm/kasan/common.c:51)
> kasan_save_free_info (/v6.1-rc2/mm/kasan/generic.c:508)
> ____kasan_slab_free (/v6.1-rc2/./include/linux/slub_def.h:164 /v6.1-rc2/mm/kasan/common.c:214)
> __kasan_slab_free (/v6.1-rc2/mm/kasan/common.c:244)
> slab_free_freelist_hook (/v6.1-rc2/mm/slub.c:381 /v6.1-rc2/mm/slub.c:1747)
> __kmem_cache_free (/v6.1-rc2/mm/slub.c:3656 /v6.1-rc2/mm/slub.c:3674)
> kfree (/v6.1-rc2/mm/slab_common.c:1007)
> __sk_destruct (/v6.1-rc2/./include/linux/cred.h:288 /v6.1-rc2/net/core/sock.c:2147)
> __sk_free (/v6.1-rc2/./include/linux/sock_diag.h:87 /v6.1-rc2/net/core/sock.c:2175)
> sk_free (/v6.1-rc2/./include/linux/instrumented.h:? /v6.1-rc2/./include/linux/atomic/atomic-instrumented.h:176 /v6.1-rc2/./include/linux/refcount.h:272 /v6.1-rc2/./include/linux/refcount.h:315 /v6.1-rc2/./include/linux/refcount.h:333 /v6.1-rc2/net/core/sock.c:2188)
> l2cap_sock_kill (/v6.1-rc2/./include/net/bluetooth/bluetooth.h:286 /v6.1-rc2/net/bluetooth/l2cap_sock.c:1284)
> l2cap_sock_close_cb (/v6.1-rc2/net/bluetooth/l2cap_sock.c:1576)
> l2cap_chan_timeout (/v6.1-rc2/./include/net/bluetooth/bluetooth.h:296 /v6.1-rc2/net/bluetooth/l2cap_core.c:462)
> process_one_work (/v6.1-rc2/kernel/workqueue.c:2225)
> worker_thread (/v6.1-rc2/kernel/workqueue.c:816 /v6.1-rc2/kernel/workqueue.c:2107 /v6.1-rc2/kernel/workqueue.c:2159 /v6.1-rc2/kernel/workqueue.c:2408)
> kthread (/v6.1-rc2/kernel/kthread.c:361)
> ret_from_fork (/v6.1-rc2/arch/x86/entry/entry_64.S:306)
> The buggy address belongs to the object at ffff88800f7f4000
>  which belongs to the cache kmalloc-1k of size 1024
> The buggy address is located 96 bytes inside of
>  1024-byte region [ffff88800f7f4000, ffff88800f7f4400)
> The buggy address belongs to the physical page:
> page:00000000b8d65c1d refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88800f7f6800 pfn:0xf7f4
> head:00000000b8d65c1d order:2 compound_mapcount:0 compound_pincount:0
> flags: 0xfffffc0010200(slab|head|node=0|zone=1|lastcpupid=0x1fffff)
> raw: 000fffffc0010200 ffffea0000993408 ffffea0000991308 ffff888005841dc0
> raw: ffff88800f7f6800 0000000000080002 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
> Memory state around the buggy address:
>  ffff88800f7f3f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>  ffff88800f7f3f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> >ffff88800f7f4000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                                                        ^
>  ffff88800f7f4080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff88800f7f4100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
>
> > >
> > > Context 2:
> > > l2cap_chan_timeout();
> > >   l2cap_chan_lock(chan);
> > >   chan->ops->close(chan);
> > >     l2cap_sock_close_cb()
> > >     l2cap_sock_kill(sk); // <-- sk is freed here
> > >   l2cap_chan_unlock(chan);
> > >
> >
> > Please add a Fixes: tag
>
> Fixes: 6c08fc896b60 ("Bluetooth: Fix refcount use-after-free issue")
> > > Signed-off-by: Sungwoo Kim <iam@sung-woo.kim>
> > > ---
> > >  net/bluetooth/l2cap_sock.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
> > > index ca8f07f35..657704059 100644
> > > --- a/net/bluetooth/l2cap_sock.c
> > > +++ b/net/bluetooth/l2cap_sock.c
> > > @@ -1245,7 +1245,7 @@ static int l2cap_sock_recvmsg(struct socket *sock, struct msghdr *msg,
> > >   */
> > >  static void l2cap_sock_kill(struct sock *sk)
> > >  {
> > > -       if (!sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket)
> > > +       if (!sk || !sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket)
> > >                 return;
> > >
> > >         BT_DBG("sk %p state %s", sk, state_to_string(sk->sk_state));
> > > --
> > > 2.25.1
> > >
diff mbox series

Patch

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index ca8f07f35..657704059 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -1245,7 +1245,7 @@  static int l2cap_sock_recvmsg(struct socket *sock, struct msghdr *msg,
  */
 static void l2cap_sock_kill(struct sock *sk)
 {
-	if (!sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket)
+	if (!sk || !sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket)
 		return;
 
 	BT_DBG("sk %p state %s", sk, state_to_string(sk->sk_state));