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SubjectKASAN: use-after-free Read in af_alg_wmem_wakeup

syzbot found the following crash on:

HEAD commit: befad944e231 Merge tag 'drm-fixes-2018-10-05' of git://ano..
git tree: upstream
console output:
kernel config:
dashboard link:
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:

BUG: KASAN: use-after-free in af_alg_sndbuf include/crypto/if_alg.h:190
BUG: KASAN: use-after-free in af_alg_writable include/crypto/if_alg.h:204
BUG: KASAN: use-after-free in af_alg_wmem_wakeup+0x711/0x7d0
Read of size 8 at addr ffff880186c705f0 by task syz-executor1/21582

CPU: 0 PID: 21582 Comm: syz-executor1 Not tainted 4.19.0-rc6+ #268
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
af_alg_sndbuf include/crypto/if_alg.h:190 [inline]
af_alg_writable include/crypto/if_alg.h:204 [inline]
af_alg_wmem_wakeup+0x711/0x7d0 crypto/af_alg.c:731
aead_recvmsg+0x53e/0x1ba0 crypto/algif_aead.c:354
sock_recvmsg_nosec net/socket.c:794 [inline]
sock_recvmsg+0xd0/0x110 net/socket.c:801
sock_read_iter+0x39b/0x570 net/socket.c:878
call_read_iter include/linux/fs.h:1802 [inline]
aio_read+0x297/0x490 fs/aio.c:1516
io_submit_one+0xac2/0xf80 fs/aio.c:1832
__do_sys_io_submit fs/aio.c:1916 [inline]
__se_sys_io_submit fs/aio.c:1887 [inline]
__x64_sys_io_submit+0x1b7/0x580 fs/aio.c:1887
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
RIP: 0033:0x457579
Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
ff 0f 83 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f2c2b30bc78 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457579
RDX: 0000000020001440 RSI: 0000000000000002 RDI: 00007f2c2b2eb000
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2c2b30c6d4
R13: 00000000004be741 R14: 00000000004ce380 R15: 00000000ffffffff

Allocated by task 21585:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
__do_kmalloc mm/slab.c:3718 [inline]
__kmalloc+0x14e/0x760 mm/slab.c:3727
kmalloc include/linux/slab.h:518 [inline]
sk_prot_alloc+0x1b0/0x2e0 net/core/sock.c:1468
sk_alloc+0x10d/0x1690 net/core/sock.c:1522
af_alg_accept+0x9d/0x7d0 crypto/af_alg.c:287
alg_accept+0x46/0x60 crypto/af_alg.c:332
__sys_accept4+0x3b2/0x8a0 net/socket.c:1590
__do_sys_accept4 net/socket.c:1625 [inline]
__se_sys_accept4 net/socket.c:1622 [inline]
__x64_sys_accept4+0x97/0xf0 net/socket.c:1622
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290

Freed by task 21580:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3498 [inline]
kfree+0xcf/0x230 mm/slab.c:3813
sk_prot_free net/core/sock.c:1505 [inline]
__sk_destruct+0x797/0xa80 net/core/sock.c:1587
sk_destruct+0x78/0x90 net/core/sock.c:1595
__sk_free+0xcf/0x300 net/core/sock.c:1606
sk_free+0x42/0x50 net/core/sock.c:1617
sock_put include/net/sock.h:1691 [inline]
af_alg_release+0x6e/0x90 crypto/af_alg.c:126
__sock_release+0xd7/0x250 net/socket.c:579
sock_close+0x19/0x20 net/socket.c:1141
__fput+0x385/0xa30 fs/file_table.c:278
____fput+0x15/0x20 fs/file_table.c:309
task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:193 [inline]
exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293

The buggy address belongs to the object at ffff880186c70180
which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 1136 bytes inside of
2048-byte region [ffff880186c70180, ffff880186c70980)
The buggy address belongs to the page:
page:ffffea00061b1c00 count:1 mapcount:0 mapping:ffff8801da800c40 index:0x0
compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffffea0007266508 ffffea0006129088 ffff8801da800c40
raw: 0000000000000000 ffff880186c70180 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff880186c70480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff880186c70500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff880186c70580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff880186c70600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff880186c70680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

This bug is generated by a bot. It may contain errors.
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