KASAN: use-after-free Read in crypto_gcm_init_common

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 4710e78940d8 Merge tag 'nfs-for-4.20-2' of git://git.linux..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17a68093400000
kernel config: https://syzkaller.appspot.com/x/.config?x=9384ecb1c973baed
dashboard link: https://syzkaller.appspot.com/bug?extid=e736399a2c4054612307
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17902f5b400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=111377e5400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e73639...@syzkaller.appspotmail.com

startpar (5496) used greatest stack depth: 15744 bytes left
==================================================================
BUG: KASAN: use-after-free in memcpy include/linux/string.h:352 [inline]
BUG: KASAN: use-after-free in crypto_gcm_init_common+0xe2/0x710
crypto/gcm.c:181
Read of size 12 at addr ffff8801d7b91b00 by task kworker/1:2/3205

CPU: 1 PID: 3205 Comm: kworker/1:2 Not tainted 4.19.0+ #320
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: pencrypt padata_parallel_worker
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x244/0x39d lib/dump_stack.c:113
print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
check_memory_region_inline mm/kasan/kasan.c:260 [inline]
check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
memcpy+0x23/0x50 mm/kasan/kasan.c:302
memcpy include/linux/string.h:352 [inline]
crypto_gcm_init_common+0xe2/0x710 crypto/gcm.c:181
crypto_gcm_encrypt+0xe2/0x6b0 crypto/gcm.c:479
crypto_aead_encrypt include/crypto/aead.h:364 [inline]
pcrypt_aead_enc+0xd6/0x340 crypto/pcrypt.c:143
padata_parallel_worker+0x49d/0x760 kernel/padata.c:86
process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153
worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
kthread+0x35a/0x440 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 5668:
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
kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620
kmalloc include/linux/slab.h:546 [inline]
tls_set_sw_offload+0xcb3/0x1390 net/tls/tls_sw.c:1945
do_tls_setsockopt_conf net/tls/tls_main.c:467 [inline]
do_tls_setsockopt net/tls/tls_main.c:514 [inline]
tls_setsockopt+0x689/0x770 net/tls/tls_main.c:533
sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:2978
__sys_setsockopt+0x1ba/0x3c0 net/socket.c:1902
__do_sys_setsockopt net/socket.c:1913 [inline]
__se_sys_setsockopt net/socket.c:1910 [inline]
__x64_sys_setsockopt+0xbe/0x150 net/socket.c:1910
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 5668:
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:3817
tls_sk_proto_close+0x5fa/0x750 net/tls/tls_main.c:277
inet_release+0x104/0x1f0 net/ipv4/af_inet.c:428
inet6_release+0x50/0x70 net/ipv6/af_inet6.c:458
__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:188 [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
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801d7b91b00
which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
32-byte region [ffff8801d7b91b00, ffff8801d7b91b20)
The buggy address belongs to the page:
page:ffffea00075ee440 count:1 mapcount:0 mapping:ffff8801da8001c0
index:0xffff8801d7b91fc1
flags: 0x2fffc0000000200(slab)
raw: 02fffc0000000200 ffffea00075effc8 ffff8801da801248 ffff8801da8001c0
raw: ffff8801d7b91fc1 ffff8801d7b91000 000000010000003f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801d7b91a00: fb fb fb fb fc fc fc fc 00 00 fc fc fc fc fc fc
ffff8801d7b91a80: 00 00 fc fc fc fc fc fc fb fb fb fb fc fc fc fc
> ffff8801d7b91b00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
^
ffff8801d7b91b80: fb fb fb fb fc fc fc fc 00 00 fc fc fc fc fc fc
ffff8801d7b91c00: 00 00 00 00 fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================


---
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[Ard Biesheuvel]

(+ TLS maintainers and netdev)

On 7 November 2018 at 02:38, syzbot

[syzbot]

syzbot has bisected this bug to:

commit 428490e38b2e352812e0b765d8bceafab0ec441d
Author: Jason A. Donenfeld <Ja...@zx2c4.com>
Date: Wed Sep 20 14:58:39 2017 +0000

security/keys: rewrite all of big_key crypto

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=160eabcf200000
start commit: 428490e3 security/keys: rewrite all of big_key crypto
git tree: upstream
final crash: https://syzkaller.appspot.com/x/report.txt?x=150eabcf200000
console output: https://syzkaller.appspot.com/x/log.txt?x=110eabcf200000

kernel config: https://syzkaller.appspot.com/x/.config?x=9384ecb1c973baed
dashboard link: https://syzkaller.appspot.com/bug?extid=e736399a2c4054612307

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17902f5b400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=111377e5400000

Reported-by: syzbot+e73639...@syzkaller.appspotmail.com
Fixes: 428490e38b2e ("security/keys: rewrite all of big_key crypto")

[Kees Cook]

Did this regression get fixed?

--
Kees Cook

[syzbot]

syzbot suspects this bug was fixed by commit:

commit 9354544cbccf68da1b047f8fb7b47630e3c8a59d
Author: Dirk van der Merwe <dirk.van...@netronome.com>
Date: Mon Jun 24 04:26:58 2019 +0000

net/tls: fix page double free on TX cleanup

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=168ad3c2600000
start commit: 4710e789 Merge tag 'nfs-for-4.20-2' of git://git.linux-nfs..
git tree: upstream

kernel config: https://syzkaller.appspot.com/x/.config?x=9384ecb1c973baed
dashboard link: https://syzkaller.appspot.com/bug?extid=e736399a2c4054612307

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17902f5b400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=111377e5400000

If the result looks correct, please mark the bug fixed by replying with:

#syz fix: net/tls: fix page double free on TX cleanup

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[Jakub Kicinski]

The bug report looks fairly strange and could indicate a double free,
but I don't see an entirely clear connection. We are double freeing a
record and its pages while the splat is from a slab-32.. Given the
bisection I think it's probably okay: