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* KASAN: use-after-free Read in netdev_name_node_lookup_rcu
@ 2020-06-30  0:40 syzbot
  2020-06-30  1:17 ` Jason A. Donenfeld
  2020-06-30  3:38 ` Cong Wang
  0 siblings, 2 replies; 4+ messages in thread
From: syzbot @ 2020-06-30  0:40 UTC (permalink / raw)
  To: Jason, davem, kuba, linux-kernel, netdev, syzkaller-bugs, wireguard

Hello,

syzbot found the following crash on:

HEAD commit:    1590a2e1 Merge tag 'acpi-5.8-rc3' of git://git.kernel.org/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1664afad100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bf3aec367b9ab569
dashboard link: https://syzkaller.appspot.com/bug?extid=a82be85e09cd5df398fe
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14a1bf1d100000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1514a06b100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a82be85e09cd5df398fe@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in strnlen+0x64/0x70 lib/string.c:561
Read of size 1 at addr ffff8880933b8c18 by task syz-executor821/6893

CPU: 0 PID: 6893 Comm: syz-executor821 Not tainted 5.8.0-rc2-syzkaller #0
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+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 strnlen+0x64/0x70 lib/string.c:561
 strnlen include/linux/string.h:339 [inline]
 dev_name_hash net/core/dev.c:208 [inline]
 netdev_name_node_lookup_rcu+0x22/0x150 net/core/dev.c:290
 dev_get_by_name_rcu net/core/dev.c:883 [inline]
 dev_get_by_name+0x7b/0x1e0 net/core/dev.c:905
 lookup_interface drivers/net/wireguard/netlink.c:63 [inline]
 wg_get_device_start+0x2e4/0x3f0 drivers/net/wireguard/netlink.c:203
 genl_start+0x342/0x6e0 net/netlink/genetlink.c:556
 __netlink_dump_start+0x585/0x900 net/netlink/af_netlink.c:2343
 genl_family_rcv_msg_dumpit+0x2ac/0x310 net/netlink/genetlink.c:638
 genl_family_rcv_msg net/netlink/genetlink.c:733 [inline]
 genl_rcv_msg+0x797/0x9e0 net/netlink/genetlink.c:753
 netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2469
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:764
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x445299
Code: Bad RIP value.
RSP: 002b:00007ffd1e794308 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000445299
RDX: 0000000000000000 RSI: 0000000020000200 RDI: 0000000000000003
RBP: 0000000000082a5d R08: 0000000000000000 R09: 00000000004002e0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402430
R13: 00000000004024c0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 6894:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0xae/0x550 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1083 [inline]
 netlink_alloc_large_skb net/netlink/af_netlink.c:1175 [inline]
 netlink_sendmsg+0x94f/0xd90 net/netlink/af_netlink.c:1893
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 6894:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x103/0x2c0 mm/slab.c:3757
 skb_free_head net/core/skbuff.c:590 [inline]
 skb_release_data+0x6d9/0x910 net/core/skbuff.c:610
 skb_release_all net/core/skbuff.c:664 [inline]
 __kfree_skb net/core/skbuff.c:678 [inline]
 consume_skb net/core/skbuff.c:837 [inline]
 consume_skb+0xc2/0x160 net/core/skbuff.c:831
 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
 netlink_unicast+0x53b/0x7d0 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8880933b8c00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 24 bytes inside of
 512-byte region [ffff8880933b8c00, ffff8880933b8e00)
The buggy address belongs to the page:
page:ffffea00024cee00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002a1da08 ffffea0002763a08 ffff8880aa000a80
raw: 0000000000000000 ffff8880933b8000 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880933b8b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880933b8b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880933b8c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff8880933b8c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880933b8d00: 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.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: KASAN: use-after-free Read in netdev_name_node_lookup_rcu
  2020-06-30  0:40 KASAN: use-after-free Read in netdev_name_node_lookup_rcu syzbot
@ 2020-06-30  1:17 ` Jason A. Donenfeld
  2020-06-30  3:33   ` Cong Wang
  2020-06-30  3:38 ` Cong Wang
  1 sibling, 1 reply; 4+ messages in thread
From: Jason A. Donenfeld @ 2020-06-30  1:17 UTC (permalink / raw)
  To: syzbot, Cong Wang, Johannes Berg
  Cc: David Miller, Jakub Kicinski, LKML, Netdev, syzkaller-bugs,
	WireGuard mailing list

Hey Cong,

I'm wondering if the below error is related to what you've been
looking at yesterday. AFAICT, there's a simple UaF on the attrbuf
passed to the start method. I recall recently you were working on the
locking in genetlink's family buffers and wound up mallocing some
things, so it seems like this might be related. See below.

Regards,
Jason

On Mon, Jun 29, 2020 at 6:40 PM syzbot
<syzbot+a82be85e09cd5df398fe@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    1590a2e1 Merge tag 'acpi-5.8-rc3' of git://git.kernel.org/..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1664afad100000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=bf3aec367b9ab569
> dashboard link: https://syzkaller.appspot.com/bug?extid=a82be85e09cd5df398fe
> compiler:       gcc (GCC) 10.1.0-syz 20200507
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14a1bf1d100000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1514a06b100000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+a82be85e09cd5df398fe@syzkaller.appspotmail.com
>
> ==================================================================
> BUG: KASAN: use-after-free in strnlen+0x64/0x70 lib/string.c:561
> Read of size 1 at addr ffff8880933b8c18 by task syz-executor821/6893
>
> CPU: 0 PID: 6893 Comm: syz-executor821 Not tainted 5.8.0-rc2-syzkaller #0
> 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+0x18f/0x20d lib/dump_stack.c:118
>  print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
>  __kasan_report mm/kasan/report.c:513 [inline]
>  kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
>  strnlen+0x64/0x70 lib/string.c:561
>  strnlen include/linux/string.h:339 [inline]
>  dev_name_hash net/core/dev.c:208 [inline]
>  netdev_name_node_lookup_rcu+0x22/0x150 net/core/dev.c:290
>  dev_get_by_name_rcu net/core/dev.c:883 [inline]
>  dev_get_by_name+0x7b/0x1e0 net/core/dev.c:905
>  lookup_interface drivers/net/wireguard/netlink.c:63 [inline]
>  wg_get_device_start+0x2e4/0x3f0 drivers/net/wireguard/netlink.c:203
>  genl_start+0x342/0x6e0 net/netlink/genetlink.c:556
>  __netlink_dump_start+0x585/0x900 net/netlink/af_netlink.c:2343
>  genl_family_rcv_msg_dumpit+0x2ac/0x310 net/netlink/genetlink.c:638
>  genl_family_rcv_msg net/netlink/genetlink.c:733 [inline]
>  genl_rcv_msg+0x797/0x9e0 net/netlink/genetlink.c:753
>  netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2469
>  genl_rcv+0x24/0x40 net/netlink/genetlink.c:764
>  netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
>  netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1329
>  netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1918
>  sock_sendmsg_nosec net/socket.c:652 [inline]
>  sock_sendmsg+0xcf/0x120 net/socket.c:672
>  ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
>  ___sys_sendmsg+0xf3/0x170 net/socket.c:2406
>  __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
>  do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x445299
> Code: Bad RIP value.
> RSP: 002b:00007ffd1e794308 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000445299
> RDX: 0000000000000000 RSI: 0000000020000200 RDI: 0000000000000003
> RBP: 0000000000082a5d R08: 0000000000000000 R09: 00000000004002e0
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402430
> R13: 00000000004024c0 R14: 0000000000000000 R15: 0000000000000000
>
> Allocated by task 6894:
>  save_stack+0x1b/0x40 mm/kasan/common.c:48
>  set_track mm/kasan/common.c:56 [inline]
>  __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
>  __kmalloc_reserve net/core/skbuff.c:142 [inline]
>  __alloc_skb+0xae/0x550 net/core/skbuff.c:210
>  alloc_skb include/linux/skbuff.h:1083 [inline]
>  netlink_alloc_large_skb net/netlink/af_netlink.c:1175 [inline]
>  netlink_sendmsg+0x94f/0xd90 net/netlink/af_netlink.c:1893
>  sock_sendmsg_nosec net/socket.c:652 [inline]
>  sock_sendmsg+0xcf/0x120 net/socket.c:672
>  ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
>  ___sys_sendmsg+0xf3/0x170 net/socket.c:2406
>  __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
>  do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> Freed by task 6894:
>  save_stack+0x1b/0x40 mm/kasan/common.c:48
>  set_track mm/kasan/common.c:56 [inline]
>  kasan_set_free_info mm/kasan/common.c:316 [inline]
>  __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
>  __cache_free mm/slab.c:3426 [inline]
>  kfree+0x103/0x2c0 mm/slab.c:3757
>  skb_free_head net/core/skbuff.c:590 [inline]
>  skb_release_data+0x6d9/0x910 net/core/skbuff.c:610
>  skb_release_all net/core/skbuff.c:664 [inline]
>  __kfree_skb net/core/skbuff.c:678 [inline]
>  consume_skb net/core/skbuff.c:837 [inline]
>  consume_skb+0xc2/0x160 net/core/skbuff.c:831
>  netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
>  netlink_unicast+0x53b/0x7d0 net/netlink/af_netlink.c:1329
>  netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1918
>  sock_sendmsg_nosec net/socket.c:652 [inline]
>  sock_sendmsg+0xcf/0x120 net/socket.c:672
>  ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
>  ___sys_sendmsg+0xf3/0x170 net/socket.c:2406
>  __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
>  do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> The buggy address belongs to the object at ffff8880933b8c00
>  which belongs to the cache kmalloc-512 of size 512
> The buggy address is located 24 bytes inside of
>  512-byte region [ffff8880933b8c00, ffff8880933b8e00)
> The buggy address belongs to the page:
> page:ffffea00024cee00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
> flags: 0xfffe0000000200(slab)
> raw: 00fffe0000000200 ffffea0002a1da08 ffffea0002763a08 ffff8880aa000a80
> raw: 0000000000000000 ffff8880933b8000 0000000100000004 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>  ffff8880933b8b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>  ffff8880933b8b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >ffff8880933b8c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                             ^
>  ffff8880933b8c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8880933b8d00: 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.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: KASAN: use-after-free Read in netdev_name_node_lookup_rcu
  2020-06-30  1:17 ` Jason A. Donenfeld
@ 2020-06-30  3:33   ` Cong Wang
  0 siblings, 0 replies; 4+ messages in thread
From: Cong Wang @ 2020-06-30  3:33 UTC (permalink / raw)
  To: Jason A. Donenfeld
  Cc: syzbot, Johannes Berg, David Miller, Jakub Kicinski, LKML,
	Netdev, syzkaller-bugs, WireGuard mailing list

On Mon, Jun 29, 2020 at 6:17 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>
> Hey Cong,

Hi, Jason

>
> I'm wondering if the below error is related to what you've been
> looking at yesterday. AFAICT, there's a simple UaF on the attrbuf
> passed to the start method. I recall recently you were working on the
> locking in genetlink's family buffers and wound up mallocing some
> things, so it seems like this might be related. See below.

Yeah, very likely it is the same bug I have fixed. I will close
this together with others.

Thanks.

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: KASAN: use-after-free Read in netdev_name_node_lookup_rcu
  2020-06-30  0:40 KASAN: use-after-free Read in netdev_name_node_lookup_rcu syzbot
  2020-06-30  1:17 ` Jason A. Donenfeld
@ 2020-06-30  3:38 ` Cong Wang
  1 sibling, 0 replies; 4+ messages in thread
From: Cong Wang @ 2020-06-30  3:38 UTC (permalink / raw)
  To: syzbot
  Cc: Jason A. Donenfeld, David Miller, Jakub Kicinski, LKML,
	Linux Kernel Network Developers, syzkaller-bugs,
	WireGuard mailing list

#syz fix: genetlink: get rid of family->attrbuf

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2020-06-30  4:00 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-06-30  0:40 KASAN: use-after-free Read in netdev_name_node_lookup_rcu syzbot
2020-06-30  1:17 ` Jason A. Donenfeld
2020-06-30  3:33   ` Cong Wang
2020-06-30  3:38 ` Cong Wang

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