BUG: corrupted list in nf_tables_commit

BUG: corrupted list in nf_tables_commit

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    51d69817 Merge tag 'platform-drivers-x86-v5.5-3' of git://..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16218315e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d9290aeb7e6cf1c4
dashboard link: https://syzkaller.appspot.com/bug?extid=37a6804945a3a13b1572
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16ad1821e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17d8fc35e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+37a6804945a3a13b1572@syzkaller.appspotmail.com

list_del corruption, ffff88808c9bb000->prev is LIST_POISON2  
(dead000000000122)
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:48!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 9707 Comm: syz-executor974 Not tainted 5.5.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:__list_del_entry_valid.cold+0x37/0x4f lib/list_debug.c:48
Code: be fd 0f 0b 4c 89 ea 4c 89 f6 48 c7 c7 20 66 71 88 e8 c0 e7 be fd 0f  
0b 4c 89 e2 4c 89 f6 48 c7 c7 80 66 71 88 e8 ac e7 be fd <0f> 0b 4c 89 f6  
48 c7 c7 40 67 71 88 e8 9b e7 be fd 0f 0b cc cc cc
RSP: 0018:ffffc900020273f0 EFLAGS: 00010282
RAX: 000000000000004e RBX: ffff88808c9bb000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815e5396 RDI: fffff52000404e70
RBP: ffffc90002027408 R08: 000000000000004e R09: ffffed1015d06621
R10: ffffed1015d06620 R11: ffff8880ae833107 R12: dead000000000122
R13: ffff888093e70d80 R14: ffff88808c9bb000 R15: dffffc0000000000
FS:  0000000000d18880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020003ac0 CR3: 0000000096a25000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  __list_del_entry include/linux/list.h:131 [inline]
  list_del_rcu include/linux/rculist.h:148 [inline]
  nf_tables_commit+0x1068/0x3b30 net/netfilter/nf_tables_api.c:7183
  nfnetlink_rcv_batch+0xc78/0x17a0 net/netfilter/nfnetlink.c:485
  nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:543 [inline]
  nfnetlink_rcv+0x3e7/0x460 net/netfilter/nfnetlink.c:561
  netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
  netlink_unicast+0x58c/0x7d0 net/netlink/af_netlink.c:1328
  netlink_sendmsg+0x91c/0xea0 net/netlink/af_netlink.c:1917
  sock_sendmsg_nosec net/socket.c:639 [inline]
  sock_sendmsg+0xd7/0x130 net/socket.c:659
  ____sys_sendmsg+0x753/0x880 net/socket.c:2330
  ___sys_sendmsg+0x100/0x170 net/socket.c:2384
  __sys_sendmsg+0x105/0x1d0 net/socket.c:2417
  __do_sys_sendmsg net/socket.c:2426 [inline]
  __se_sys_sendmsg net/socket.c:2424 [inline]
  __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2424
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x441aa9
Code: e8 fc ab 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 9b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffcfa467588 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441aa9
RDX: 0000000000000042 RSI: 0000000020003ac0 RDI: 0000000000000003
RBP: 0000000000006f6c R08: 00000000004002c8 R09: 00000000004002c8
R10: 0000000000000004 R11: 0000000000000246 R12: 00000000004028d0
R13: 0000000000402960 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 9581ba900963d50f ]---
RIP: 0010:__list_del_entry_valid.cold+0x37/0x4f lib/list_debug.c:48
Code: be fd 0f 0b 4c 89 ea 4c 89 f6 48 c7 c7 20 66 71 88 e8 c0 e7 be fd 0f  
0b 4c 89 e2 4c 89 f6 48 c7 c7 80 66 71 88 e8 ac e7 be fd <0f> 0b 4c 89 f6  
48 c7 c7 40 67 71 88 e8 9b e7 be fd 0f 0b cc cc cc
RSP: 0018:ffffc900020273f0 EFLAGS: 00010282
RAX: 000000000000004e RBX: ffff88808c9bb000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815e5396 RDI: fffff52000404e70
RBP: ffffc90002027408 R08: 000000000000004e R09: ffffed1015d06621
R10: ffffed1015d06620 R11: ffff8880ae833107 R12: dead000000000122
R13: ffff888093e70d80 R14: ffff88808c9bb000 R15: dffffc0000000000
FS:  0000000000d18880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020003ac0 CR3: 0000000096a25000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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[PATCH nf] netfilter: nf_tables: fix flowtable list del corruption

[Florian Westphal]

syzbot reported following crash:

  list_del corruption, ffff88808c9bb000->prev is LIST_POISON2 (dead000000000122)
  [..]
  Call Trace:
   __list_del_entry include/linux/list.h:131 [inline]
   list_del_rcu include/linux/rculist.h:148 [inline]
   nf_tables_commit+0x1068/0x3b30 net/netfilter/nf_tables_api.c:7183
   [..]

The commit transaction list has:

NFT_MSG_NEWTABLE
NFT_MSG_NEWFLOWTABLE
NFT_MSG_DELFLOWTABLE
NFT_MSG_DELTABLE

A missing generation check during DELTABLE processing causes it to queue
the DELFLOWTABLE operation a second time, so we corrupt the list here:

  case NFT_MSG_DELFLOWTABLE:
     list_del_rcu(&nft_trans_flowtable(trans)->list);
     nf_tables_flowtable_notify(&trans->ctx,

because we have two different DELFLOWTABLE transactions for the same
flowtable.  We then call list_del_rcu() twice for the same flowtable->list.

The object handling seems to suffer from the same bug so add a generation
check too and only queue delete transactions for flowtables/objects that
are still active in the next generation.

Reported-by: syzbot+37a6804945a3a13b1572@syzkaller.appspotmail.com
Fixes: 3b49e2e94e6eb ("netfilter: nf_tables: add flow table netlink frontend")
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/nf_tables_api.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 5a1a6632e3a6..9ba1747686ed 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1047,12 +1047,18 @@ static int nft_flush_table(struct nft_ctx *ctx)
 	}
 
 	list_for_each_entry_safe(flowtable, nft, &ctx->table->flowtables, list) {
+		if (!nft_is_active_next(ctx->net, flowtable))
+			continue;
+
 		err = nft_delflowtable(ctx, flowtable);
 		if (err < 0)
 			goto out;
 	}
 
 	list_for_each_entry_safe(obj, ne, &ctx->table->objects, list) {
+		if (!nft_is_active_next(ctx->net, obj))
+			continue;
+
 		err = nft_delobj(ctx, obj);
 		if (err < 0)
 			goto out;
-- 
2.24.1

Re: [PATCH nf] netfilter: nf_tables: fix flowtable list del corruption

[Pablo Neira Ayuso]

On Thu, Jan 16, 2020 at 12:03:01PM +0100, Florian Westphal wrote:
> syzbot reported following crash:
> 
>   list_del corruption, ffff88808c9bb000->prev is LIST_POISON2 (dead000000000122)
>   [..]
>   Call Trace:
>    __list_del_entry include/linux/list.h:131 [inline]
>    list_del_rcu include/linux/rculist.h:148 [inline]
>    nf_tables_commit+0x1068/0x3b30 net/netfilter/nf_tables_api.c:7183
>    [..]
> 
> The commit transaction list has:
> 
> NFT_MSG_NEWTABLE
> NFT_MSG_NEWFLOWTABLE
> NFT_MSG_DELFLOWTABLE
> NFT_MSG_DELTABLE
> 
> A missing generation check during DELTABLE processing causes it to queue
> the DELFLOWTABLE operation a second time, so we corrupt the list here:
> 
>   case NFT_MSG_DELFLOWTABLE:
>      list_del_rcu(&nft_trans_flowtable(trans)->list);
>      nf_tables_flowtable_notify(&trans->ctx,
> 
> because we have two different DELFLOWTABLE transactions for the same
> flowtable.  We then call list_del_rcu() twice for the same flowtable->list.
> 
> The object handling seems to suffer from the same bug so add a generation
> check too and only queue delete transactions for flowtables/objects that
> are still active in the next generation.

Applied, thanks.

Re: BUG: corrupted list in nf_tables_commit

[syzbot]

syzbot has bisected this bug to:

commit 7c23b629a8085b11daccd68c62b5116ff498f84a
Author: Pablo Neira Ayuso <pablo@netfilter.org>
Date:   Sun Jan 7 00:04:22 2018 +0000

     netfilter: flow table support for the mixed IPv4/IPv6 family

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=146472d1e00000
start commit:   51d69817 Merge tag 'platform-drivers-x86-v5.5-3' of git://..
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=166472d1e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=126472d1e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d9290aeb7e6cf1c4
dashboard link: https://syzkaller.appspot.com/bug?extid=37a6804945a3a13b1572
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17241c76e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13118315e00000

Reported-by: syzbot+37a6804945a3a13b1572@syzkaller.appspotmail.com
Fixes: 7c23b629a808 ("netfilter: flow table support for the mixed IPv4/IPv6  
family")

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