KASAN: use-after-free Read in tls_push_sg

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 35c99ffa Merge tag 'for_linus' of git://git.kernel.org/pub..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10ff3322a00000
kernel config: https://syzkaller.appspot.com/x/.config?x=82f0809e8f0a8c87
dashboard link: https://syzkaller.appspot.com/bug?extid=66fbe4719f6ef22754ee
compiler: gcc (GCC) 9.0.0 20181231 (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:
Reported-by: syzbot+66fbe4...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in tls_push_sg+0x5e2/0x680 net/tls/tls_main.c:139
Read of size 4 at addr ffff888066f4d584 by task syz-executor.1/28368

CPU: 0 PID: 28368 Comm: syz-executor.1 Not tainted 5.1.0+ #9
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+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
__kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
kasan_report+0x12/0x20 mm/kasan/common.c:614
__asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131
tls_push_sg+0x5e2/0x680 net/tls/tls_main.c:139
tls_push_partial_record net/tls/tls_main.c:208 [inline]
tls_complete_pending_work include/net/tls.h:382 [inline]
tls_sk_proto_close+0x4a8/0x780 net/tls/tls_main.c:282
inet_release+0x105/0x1f0 net/ipv4/af_inet.c:432
inet6_release+0x53/0x80 net/ipv6/af_inet6.c:474
__sock_release+0xd3/0x2b0 net/socket.c:607
sock_close+0x1b/0x30 net/socket.c:1279
__fput+0x302/0x890 fs/file_table.c:279
____fput+0x16/0x20 fs/file_table.c:312
task_work_run+0x14a/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:168
prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
do_syscall_64+0x594/0x680 arch/x86/entry/common.c:304
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x412b61
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 e4 1a 00 00 c3 48
83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48
89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007fff8622b0f0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000412b61
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 0000000000000001 R08: 00000000bb5eab81 R09: 00000000bb5eab85
R10: 00007fff8622b1d0 R11: 0000000000000293 R12: 000000000073c900
R13: 000000000073c900 R14: 00000000002190c3 R15: 000000000073bfac

Allocated by task 28369:
save_stack+0x23/0x90 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_kmalloc mm/kasan/common.c:489 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503
__do_kmalloc mm/slab.c:3690 [inline]
__kmalloc+0x15c/0x740 mm/slab.c:3699
kmalloc include/linux/slab.h:552 [inline]
kzalloc include/linux/slab.h:742 [inline]
tls_get_rec+0x104/0x590 net/tls/tls_sw.c:322
tls_sw_sendmsg+0xda5/0x17b0 net/tls/tls_sw.c:928
inet_sendmsg+0x147/0x5e0 net/ipv4/af_inet.c:802
sock_sendmsg_nosec net/socket.c:660 [inline]
sock_sendmsg+0xf2/0x170 net/socket.c:671
__sys_sendto+0x262/0x380 net/socket.c:1964
__do_sys_sendto net/socket.c:1976 [inline]
__se_sys_sendto net/socket.c:1972 [inline]
__x64_sys_sendto+0xe1/0x1a0 net/socket.c:1972
do_syscall_64+0x103/0x680 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 4964:
save_stack+0x23/0x90 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
__cache_free mm/slab.c:3462 [inline]
kfree+0xcf/0x230 mm/slab.c:3785
tls_tx_records+0x4c6/0x760 net/tls/tls_sw.c:408
tx_work_handler+0xba/0xf0 net/tls/tls_sw.c:2150
process_one_work+0x98e/0x1790 kernel/workqueue.c:2268
worker_thread+0x98/0xe40 kernel/workqueue.c:2414
kthread+0x357/0x430 kernel/kthread.c:253
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff888066f4d280
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 772 bytes inside of
2048-byte region [ffff888066f4d280, ffff888066f4da80)
The buggy address belongs to the page:
page:ffffea00019bd300 count:1 mapcount:0 mapping:ffff8880aa400c40 index:0x0
compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea0002413588 ffffea0001aa2a08 ffff8880aa400c40
raw: 0000000000000000 ffff888066f4c180 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888066f4d480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888066f4d500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff888066f4d580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888066f4d600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888066f4d680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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[Jakub Kicinski]

On Fri, 17 May 2019 11:40:05 -0700, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 35c99ffa Merge tag 'for_linus' of git://git.kernel.org/pub..
> git tree: net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=10ff3322a00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=82f0809e8f0a8c87
> dashboard link: https://syzkaller.appspot.com/bug?extid=66fbe4719f6ef22754ee
> compiler: gcc (GCC) 9.0.0 20181231 (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:
> Reported-by: syzbot+66fbe4...@syzkaller.appspotmail.com

Most likely:

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