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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cbfa1702 Linux 4.14.198
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1579c2f0500000
kernel config: https://syzkaller.appspot.com/x/.config?x=3990958d85b55e59
dashboard link: https://syzkaller.appspot.com/bug?extid=a4de850f8ed5032d0f32
compiler: gcc (GCC) 10.1.0-syz 20200507

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a4de85...@syzkaller.appspotmail.com

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
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.