syzbot

audit: type=1400 audit(1512850514.083:7): avc:  denied  { map } for  pid=3149 comm="syzkaller168370" path="/root/syzkaller168370441" dev="sda1" ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
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BUG: KASAN: use-after-free in crypto_aead_alg include/crypto/aead.h:198 [inline]
BUG: KASAN: use-after-free in crypto_aead_encrypt include/crypto/aead.h:330 [inline]
BUG: KASAN: use-after-free in _aead_recvmsg crypto/algif_aead.c:308 [inline]
BUG: KASAN: use-after-free in aead_recvmsg+0x1758/0x1bc0 crypto/algif_aead.c:329
Read of size 4 at addr ffff8801c5259e5c by task syzkaller168370/3149

CPU: 0 PID: 3149 Comm: syzkaller168370 Not tainted 4.15.0-rc2+ #214
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+0x194/0x257 lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429
 crypto_aead_alg include/crypto/aead.h:198 [inline]
 crypto_aead_encrypt include/crypto/aead.h:330 [inline]
 _aead_recvmsg crypto/algif_aead.c:308 [inline]
 aead_recvmsg+0x1758/0x1bc0 crypto/algif_aead.c:329
 sock_recvmsg_nosec net/socket.c:809 [inline]
 sock_recvmsg+0xc9/0x110 net/socket.c:816
 ___sys_recvmsg+0x29b/0x630 net/socket.c:2185
 __sys_recvmsg+0xe2/0x210 net/socket.c:2230
 SYSC_recvmsg net/socket.c:2242 [inline]
 SyS_recvmsg+0x2d/0x50 net/socket.c:2237
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x440009
RSP: 002b:00007ffee19bc768 EFLAGS: 00000286 ORIG_RAX: 000000000000002f
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440009
RDX: 0000000000002021 RSI: 0000000020b2dfc8 RDI: 0000000000000004
RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000286 R12: 0000000000401970
R13: 0000000000401a00 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 3149:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 __do_kmalloc mm/slab.c:3711 [inline]
 __kmalloc+0x162/0x760 mm/slab.c:3720
 kmalloc include/linux/slab.h:504 [inline]
 kzalloc include/linux/slab.h:688 [inline]
 crypto_create_tfm+0x82/0x2e0 crypto/api.c:455
 crypto_alloc_tfm+0x10e/0x2f0 crypto/api.c:540
 crypto_alloc_skcipher+0x2c/0x40 crypto/skcipher.c:929
 crypto_get_default_null_skcipher+0x5f/0x80 crypto/crypto_null.c:164
 crypto_get_default_null_skcipher2 include/crypto/null.h:17 [inline]
 aead_bind+0x89/0x140 crypto/algif_aead.c:488
 alg_bind+0x1ab/0x440 crypto/af_alg.c:179
 SYSC_bind+0x1b4/0x3f0 net/socket.c:1454
 SyS_bind+0x24/0x30 net/socket.c:1440
 entry_SYSCALL_64_fastpath+0x1f/0x96

Freed by task 3149:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3491 [inline]
 kfree+0xca/0x250 mm/slab.c:3806
 kzfree+0x28/0x30 mm/slab_common.c:1482
 crypto_destroy_tfm+0x140/0x2e0 crypto/api.c:581
 crypto_free_skcipher include/crypto/skcipher.h:212 [inline]
 crypto_put_default_null_skcipher+0x35/0x60 crypto/crypto_null.c:185
 crypto_put_default_null_skcipher2 include/crypto/null.h:22 [inline]
 aead_sock_destruct+0x13c/0x220 crypto/algif_aead.c:538
 __sk_destruct+0xfd/0x910 net/core/sock.c:1558
 sk_destruct+0x47/0x80 net/core/sock.c:1593
 __sk_free+0x57/0x230 net/core/sock.c:1601
 sk_free+0x2a/0x40 net/core/sock.c:1612
 sock_put include/net/sock.h:1651 [inline]
 af_alg_release+0x5d/0x70 crypto/af_alg.c:126
 sock_release+0x8d/0x1e0 net/socket.c:600
 sock_close+0x16/0x20 net/socket.c:1129
 __fput+0x333/0x7f0 fs/file_table.c:210
 ____fput+0x15/0x20 fs/file_table.c:244
 task_work_run+0x199/0x270 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x296/0x310 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264
 entry_SYSCALL_64_fastpath+0x94/0x96

The buggy address belongs to the object at ffff8801c5259e40
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 28 bytes inside of
 128-byte region [ffff8801c5259e40, ffff8801c5259ec0)
The buggy address belongs to the page:
page:00000000ac68fd2d count:1 mapcount:0 mapping:000000003296ebe9 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c5259000 0000000000000000 0000000100000015
raw: ffffea00071653a0 ffffea0007133320 ffff8801db000640 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c5259d00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801c5259d80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801c5259e00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                                    ^
 ffff8801c5259e80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801c5259f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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