syzbot


KASAN: use-after-free Write in ex_handler_refcount (2)

Status: auto-closed as invalid on 2021/02/06 10:12
Reported-by: syzbot+a4de850f8ed5032d0f32@syzkaller.appspotmail.com
First crash: 628d, last: 628d
similar bugs (5):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 KASAN: use-after-free Write in ex_handler_refcount C done 16 665d 874d 1/1 fixed on 2020/10/03 03:40
android-54 KASAN: use-after-free Write in ex_handler_refcount syz 4 667d 669d 0/2 upstream: reported syz repro on 2020/08/29 07:49
linux-4.14 KASAN: use-after-free Write in ex_handler_refcount (3) C 32 6d08h 493d 0/1 upstream: reported C repro on 2021/02/20 19:09
linux-4.19 KASAN: use-after-free Write in ex_handler_refcount (2) C error 32 6d09h 457d 0/1 upstream: reported C repro on 2021/03/29 13:41
linux-4.19 KASAN: use-after-free Write in ex_handler_refcount C done 11 665d 873d 1/1 fixed on 2020/10/02 13:00

Sample crash report:
EXT4-fs (loop3): mounted filesystem without journal. Opts: ,errors=continue
==================================================================
BUG: KASAN: use-after-free in ex_handler_refcount+0x164/0x1a0 arch/x86/mm/extable.c:49
Write of size 4 at addr ffff888050422c00 by task syz-executor.0/16835

CPU: 1 PID: 16835 Comm: syz-executor.0 Not tainted 4.14.198-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_store4_noabort+0x68/0x70 mm/kasan/report.c:434
 ex_handler_refcount+0x164/0x1a0 arch/x86/mm/extable.c:49
 fixup_exception+0x8a/0xc3 arch/x86/mm/extable.c:197
 do_trap_no_signal arch/x86/kernel/traps.c:208 [inline]
 do_trap+0x61/0x250 arch/x86/kernel/traps.c:257
 do_error_trap+0x132/0x2d0 arch/x86/kernel/traps.c:301
 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:964
RIP: 0010:inat_get_avx_attribute+0x5331/0x6aaf
RSP: 0018:ffff88804b4b7ab8 EFLAGS: 00010297
RAX: 0000000000040000 RBX: ffff8880911b68c0 RCX: ffff888050422c00
RDX: 000000000002e338 RSI: ffffffff85ba0513 RDI: 0000000000000286
RBP: ffff888050422b80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a55e0900
R13: dffffc0000000000 R14: 0000000000000067 R15: ffff8880911b6d48
 l2cap_sock_kill net/bluetooth/l2cap_sock.c:1313 [inline]
 l2cap_sock_close_cb+0x94/0xb0 net/bluetooth/l2cap_sock.c:1312
 l2cap_conn_del+0x3a3/0x670 net/bluetooth/l2cap_core.c:1730
 l2cap_disconn_cfm net/bluetooth/l2cap_core.c:7435 [inline]
 l2cap_disconn_cfm+0x6b/0x80 net/bluetooth/l2cap_core.c:7428
 hci_disconn_cfm include/net/bluetooth/hci_core.h:1226 [inline]
 hci_conn_hash_flush+0x114/0x220 net/bluetooth/hci_conn.c:1376
 hci_dev_do_close+0x542/0xc50 net/bluetooth/hci_core.c:1620
 hci_rfkill_set_block net/bluetooth/hci_core.c:2050 [inline]
 hci_rfkill_set_block+0x94/0xe0 net/bluetooth/hci_core.c:2037
 rfkill_set_block+0x1b2/0x4a0 net/rfkill/core.c:337
 rfkill_fop_write+0x1b6/0x3c0 net/rfkill/core.c:1233
 __vfs_write+0xe4/0x630 fs/read_write.c:480
 vfs_write+0x17f/0x4d0 fs/read_write.c:544
 SYSC_write fs/read_write.c:590 [inline]
 SyS_write+0xf2/0x210 fs/read_write.c:582
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45de29
RSP: 002b:00007f9c30590c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000003af00 RCX: 000000000045de29
RDX: 0000000000000008 RSI: 0000000020000180 RDI: 0000000000000003
RBP: 000000000118bf60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c
R13: 00007ffee996513f R14: 00007f9c305919c0 R15: 000000000118bf2c

Allocated by task 14921:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15a/0x400 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 sk_prot_alloc+0x1ba/0x290 net/core/sock.c:1467
 sk_alloc+0x36/0xcd0 net/core/sock.c:1521
 l2cap_sock_alloc.constprop.0+0x31/0x210 net/bluetooth/l2cap_sock.c:1591
 l2cap_sock_create+0xdd/0x170 net/bluetooth/l2cap_sock.c:1637
 bt_sock_create+0x13b/0x280 net/bluetooth/af_bluetooth.c:130
 __sock_create+0x303/0x620 net/socket.c:1275
 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+0x6ec/0xc00 net/bluetooth/rfcomm/core.c:431
 rfcomm_sock_connect+0x2c6/0x3c0 net/bluetooth/rfcomm/sock.c:415
 SYSC_connect net/socket.c:1655 [inline]
 SyS_connect+0x1f4/0x240 net/socket.c:1636
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 3542:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 sk_prot_free net/core/sock.c:1504 [inline]
 __sk_destruct+0x577/0x6e0 net/core/sock.c:1582
 sk_destruct net/core/sock.c:1597 [inline]
 __sk_free+0xd9/0x2d0 net/core/sock.c:1605
 sk_free+0x2b/0x40 net/core/sock.c:1616
 sock_put include/net/sock.h:1662 [inline]
 l2cap_sock_kill.part.0+0x5b/0x70 net/bluetooth/l2cap_sock.c:1056
 l2cap_sock_kill net/bluetooth/l2cap_sock.c:1207 [inline]
 l2cap_sock_release+0x146/0x180 net/bluetooth/l2cap_sock.c:1205
 __sock_release net/socket.c:602 [inline]
 sock_release+0x87/0x1e0 net/socket.c:623
 rfcomm_session_del+0x14f/0x1e0 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+0x1127/0x3ca0 net/bluetooth/rfcomm/core.c:2087
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

The buggy address belongs to the object at ffff888050422b80
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 128 bytes inside of
 2048-byte region [ffff888050422b80, ffff888050423380)
The buggy address belongs to the page:
page:ffffea0001410880 count:1 mapcount:0 mapping:ffff888050422300 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffff888050422300 0000000000000000 0000000100000003
raw: ffffea000245faa0 ffffea0002820720 ffff88812fe50c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888050422b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888050422b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888050422c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888050422c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888050422d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2020/10/09 10:11 linux-4.14.y cbfa1702aaf6 fa79ed2a .config log report info