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KASAN: use-after-free Read in l2cap_sock_kill

Status: upstream: reported C repro on 2020/09/18 18:43
Reported-by: syzbot+b673a563b3a339728b15@syzkaller.appspotmail.com
First crash: 1314d, last: 1302d
Fix bisection the fix commit could be any of (bisect log):
  52f5a09ab758 mm/swapfile.c: swap_next should increase position index
  3b73af6cb955 Bluetooth: Fix refcount use-after-free issue
  f9cb6b6124ac mm: pagewalk: fix termination condition in walk_pte_range()
  4b0795d5b615 Bluetooth: prefetch channel before killing sock
   
▶ ▼ Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in l2cap_sock_kill bluetooth 1 1250d 1250d 0/26 auto-closed as invalid on 2021/02/19 19:34

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in constant_test_bit arch/x86/include/asm/bitops.h:317 [inline]
BUG: KASAN: use-after-free in sock_flag include/net/sock.h:839 [inline]
BUG: KASAN: use-after-free in l2cap_sock_kill+0xdb/0x100 net/bluetooth/l2cap_sock.c:1046
Read of size 8 at addr ffff88808e241660 by task kworker/0:1/6481

CPU: 0 PID: 6481 Comm: kworker/0:1 Not tainted 4.19.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x22c/0x33e lib/dump_stack.c:118
 print_address_description.cold+0x56/0x25c mm/kasan/report.c:256
 kasan_report_error.cold+0x66/0xb9 mm/kasan/report.c:354
 kasan_report mm/kasan/report.c:412 [inline]
 __asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
 constant_test_bit arch/x86/include/asm/bitops.h:317 [inline]
 sock_flag include/net/sock.h:839 [inline]
 l2cap_sock_kill+0xdb/0x100 net/bluetooth/l2cap_sock.c:1046
 l2cap_chan_timeout+0x1bb/0x210 net/bluetooth/l2cap_core.c:431
 process_one_work+0x796/0x14e0 kernel/workqueue.c:2155
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2298
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 22133:
 __do_kmalloc mm/slab.c:3727 [inline]
 __kmalloc+0x15a/0x4f0 mm/slab.c:3736
 kmalloc include/linux/slab.h:520 [inline]
 sk_prot_alloc+0x1e2/0x2d0 net/core/sock.c:1466
 sk_alloc+0x36/0x1100 net/core/sock.c:1520
 l2cap_sock_alloc.constprop.0+0x31/0x210 net/bluetooth/l2cap_sock.c:1590
 l2cap_sock_create+0x110/0x1b0 net/bluetooth/l2cap_sock.c:1636
 bt_sock_create+0x1d0/0x470 net/bluetooth/af_bluetooth.c:130
 __sock_create+0x495/0x820 net/socket.c:1276
 rfcomm_l2sock_create net/bluetooth/rfcomm/core.c:203 [inline]
 rfcomm_session_create net/bluetooth/rfcomm/core.c:738 [inline]
 __rfcomm_dlc_open net/bluetooth/rfcomm/core.c:388 [inline]
 rfcomm_dlc_open+0x6da/0xc50 net/bluetooth/rfcomm/core.c:431
 rfcomm_sock_connect+0x317/0x420 net/bluetooth/rfcomm/sock.c:416
 __sys_connect+0x265/0x2c0 net/socket.c:1663
 __do_sys_connect net/socket.c:1674 [inline]
 __se_sys_connect net/socket.c:1671 [inline]
 __x64_sys_connect+0x6f/0xb0 net/socket.c:1671
 do_syscall_64+0xf9/0x670 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 3608:
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xcc/0x250 mm/slab.c:3822
 sk_prot_free net/core/sock.c:1503 [inline]
 __sk_destruct+0x61d/0x830 net/core/sock.c:1584
 sk_destruct net/core/sock.c:1599 [inline]
 __sk_free+0x165/0x3b0 net/core/sock.c:1610
 sk_free+0x3b/0x50 net/core/sock.c:1621
 sock_put include/net/sock.h:1711 [inline]
 l2cap_sock_kill+0xd4/0x100 net/bluetooth/l2cap_sock.c:1055
 l2cap_sock_release+0xd9/0x100 net/bluetooth/l2cap_sock.c:1204
 __sock_release net/socket.c:579 [inline]
 sock_release+0x87/0x1d0 net/socket.c:599
 rfcomm_session_del+0x15a/0x1f0 net/bluetooth/rfcomm/core.c:684
 rfcomm_session_close net/bluetooth/rfcomm/core.c:723 [inline]
 rfcomm_process_rx net/bluetooth/rfcomm/core.c:1916 [inline]
 rfcomm_process_sessions net/bluetooth/rfcomm/core.c:2000 [inline]
 rfcomm_run+0x13c4/0x45d1 net/bluetooth/rfcomm/core.c:2087
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

The buggy address belongs to the object at ffff88808e241600
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 96 bytes inside of
 2048-byte region [ffff88808e241600, ffff88808e241e00)
The buggy address belongs to the page:
page:ffffea0002389000 count:1 mapcount:0 mapping:ffff88812c3f6c40 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffffea00023ead88 ffffea0002387f08 ffff88812c3f6c40
raw: 0000000000000000 ffff88808e240500 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808e241500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808e241580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88808e241600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff88808e241680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808e241700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (59):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/09/24 06:04 linux-4.19.y d09b80172c22 54289b08 .config console log report syz C ci2-linux-4-19
2020/10/01 09:54 linux-4.19.y 10ad6cfd5736 4103fce0 .config console log report info ci2-linux-4-19
2020/09/30 23:27 linux-4.19.y 10ad6cfd5736 a9767fb2 .config console log report info ci2-linux-4-19
2020/09/30 15:58 linux-4.19.y 10ad6cfd5736 8516f6d3 .config console log report info ci2-linux-4-19
2020/09/30 11:21 linux-4.19.y 10ad6cfd5736 8516f6d3 .config console log report info ci2-linux-4-19
2020/09/30 06:55 linux-4.19.y 10ad6cfd5736 8516f6d3 .config console log report info ci2-linux-4-19
2020/09/30 05:02 linux-4.19.y 10ad6cfd5736 5abc3f1a .config console log report info ci2-linux-4-19
2020/09/30 03:45 linux-4.19.y 10ad6cfd5736 5abc3f1a .config console log report info ci2-linux-4-19
2020/09/30 01:13 linux-4.19.y 10ad6cfd5736 5abc3f1a .config console log report info ci2-linux-4-19
2020/09/29 15:37 linux-4.19.y 10ad6cfd5736 5abc3f1a .config console log report info ci2-linux-4-19
2020/09/29 00:39 linux-4.19.y 10ad6cfd5736 1b88c6d5 .config console log report info ci2-linux-4-19
2020/09/28 22:50 linux-4.19.y 10ad6cfd5736 6bfdbe89 .config console log report info ci2-linux-4-19
2020/09/28 14:46 linux-4.19.y 10ad6cfd5736 6bfdbe89 .config console log report info ci2-linux-4-19
2020/09/28 13:54 linux-4.19.y 10ad6cfd5736 6bfdbe89 .config console log report info ci2-linux-4-19
2020/09/28 09:53 linux-4.19.y 10ad6cfd5736 6bfdbe89 .config console log report info ci2-linux-4-19
2020/09/28 09:45 linux-4.19.y 10ad6cfd5736 6bfdbe89 .config console log report info ci2-linux-4-19
2020/09/28 01:10 linux-4.19.y 10ad6cfd5736 5dd8aee8 .config console log report info ci2-linux-4-19
2020/09/28 01:10 linux-4.19.y 10ad6cfd5736 5dd8aee8 .config console log report info ci2-linux-4-19
2020/09/27 07:02 linux-4.19.y 10ad6cfd5736 5dd8aee8 .config console log report info ci2-linux-4-19
2020/09/27 05:21 linux-4.19.y 10ad6cfd5736 5dd8aee8 .config console log report info ci2-linux-4-19
2020/09/27 05:11 linux-4.19.y 10ad6cfd5736 5dd8aee8 .config console log report info ci2-linux-4-19
2020/09/27 01:11 linux-4.19.y 10ad6cfd5736 5dd8aee8 .config console log report info ci2-linux-4-19
2020/09/27 01:04 linux-4.19.y 10ad6cfd5736 5dd8aee8 .config console log report info ci2-linux-4-19
2020/09/26 15:06 linux-4.19.y d09b80172c22 2d5ea0cb .config console log report info ci2-linux-4-19
2020/09/26 12:48 linux-4.19.y d09b80172c22 2d5ea0cb .config console log report info ci2-linux-4-19
2020/09/26 12:44 linux-4.19.y d09b80172c22 2d5ea0cb .config console log report info ci2-linux-4-19
2020/09/26 12:09 linux-4.19.y d09b80172c22 2d5ea0cb .config console log report info ci2-linux-4-19
2020/09/26 11:22 linux-4.19.y d09b80172c22 2d5ea0cb .config console log report info ci2-linux-4-19
2020/09/25 21:57 linux-4.19.y d09b80172c22 4a006f63 .config console log report info ci2-linux-4-19
2020/09/25 13:52 linux-4.19.y d09b80172c22 4a006f63 .config console log report info ci2-linux-4-19
2020/09/25 13:28 linux-4.19.y d09b80172c22 4a006f63 .config console log report info ci2-linux-4-19
2020/09/24 14:01 linux-4.19.y d09b80172c22 54289b08 .config console log report info ci2-linux-4-19
2020/09/24 04:51 linux-4.19.y d09b80172c22 54289b08 .config console log report info ci2-linux-4-19
2020/09/24 04:48 linux-4.19.y d09b80172c22 54289b08 .config console log report info ci2-linux-4-19
2020/09/24 04:46 linux-4.19.y d09b80172c22 54289b08 .config console log report info ci2-linux-4-19
2020/09/23 20:54 linux-4.19.y d09b80172c22 54289b08 .config console log report info ci2-linux-4-19
2020/09/23 20:09 linux-4.19.y d09b80172c22 54289b08 .config console log report info ci2-linux-4-19
2020/09/23 19:54 linux-4.19.y d09b80172c22 54289b08 .config console log report info ci2-linux-4-19
2020/09/23 19:36 linux-4.19.y d09b80172c22 54289b08 .config console log report info ci2-linux-4-19
2020/09/23 12:11 linux-4.19.y d09b80172c22 287cd75a .config console log report info ci2-linux-4-19
2020/09/23 08:13 linux-4.19.y 015e94d0e37b 287cd75a .config console log report info ci2-linux-4-19
2020/09/23 08:06 linux-4.19.y 015e94d0e37b 287cd75a .config console log report info ci2-linux-4-19
2020/09/22 20:22 linux-4.19.y 015e94d0e37b 3e8f6c27 .config console log report info ci2-linux-4-19
2020/09/22 09:40 linux-4.19.y 015e94d0e37b 3e8f6c27 .config console log report info ci2-linux-4-19
2020/09/21 21:31 linux-4.19.y 015e94d0e37b 9e1fa68e .config console log report info ci2-linux-4-19
2020/09/21 20:58 linux-4.19.y 015e94d0e37b 9e1fa68e .config console log report info ci2-linux-4-19
2020/09/21 20:44 linux-4.19.y 015e94d0e37b 9e1fa68e .config console log report info ci2-linux-4-19
2020/09/21 20:11 linux-4.19.y 015e94d0e37b 9e1fa68e .config console log report info ci2-linux-4-19
2020/09/21 16:10 linux-4.19.y 015e94d0e37b c81d99c8 .config console log report info ci2-linux-4-19
2020/09/21 13:41 linux-4.19.y 015e94d0e37b c81d99c8 .config console log report info ci2-linux-4-19
2020/09/21 02:18 linux-4.19.y 015e94d0e37b 9564d2e9 .config console log report info ci2-linux-4-19
2020/09/18 18:42 linux-4.19.y 015e94d0e37b 38962c8b .config console log report info ci2-linux-4-19
* Struck through repros no longer work on HEAD.