[syzbot] KASAN: slab-out-of-bounds Read in cttimeout_net_exit

[syzbot] KASAN: slab-out-of-bounds Read in cttimeout_net_exit

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    65a9dedc11d6 net: phy: marvell: Add errata section 5.1 for..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16fafa9ef00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c05eee2efc702eed
dashboard link: https://syzkaller.appspot.com/bug?extid=92968395eedbdbd3617d
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+92968395eedbdbd3617d@syzkaller.appspotmail.com

bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
bond0 (unregistering): Released all slaves
==================================================================
BUG: KASAN: slab-out-of-bounds in __list_del_entry_valid+0xcc/0xf0 lib/list_debug.c:42
Read of size 8 at addr ffff888051af75b8 by task kworker/u4:5/1223

CPU: 1 PID: 1223 Comm: kworker/u4:5 Not tainted 5.18.0-rc6-syzkaller-01553-g65a9dedc11d6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description.constprop.0.cold+0xeb/0x495 mm/kasan/report.c:313
 print_report mm/kasan/report.c:429 [inline]
 kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491
 __list_del_entry_valid+0xcc/0xf0 lib/list_debug.c:42
 __list_del_entry include/linux/list.h:134 [inline]
 list_del include/linux/list.h:148 [inline]
 cttimeout_net_exit+0x211/0x540 net/netfilter/nfnetlink_cttimeout.c:617
 ops_exit_list+0xb0/0x170 net/core/net_namespace.c:162
 cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:594
 process_one_work+0x996/0x1610 kernel/workqueue.c:2289
 worker_thread+0x665/0x1080 kernel/workqueue.c:2436
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>

Allocated by task 9270:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:436 [inline]
 ____kasan_kmalloc mm/kasan/common.c:515 [inline]
 ____kasan_kmalloc mm/kasan/common.c:474 [inline]
 __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:524
 kmalloc include/linux/slab.h:586 [inline]
 kzalloc include/linux/slab.h:714 [inline]
 cttimeout_new_timeout+0x51f/0xa50 net/netfilter/nfnetlink_cttimeout.c:156
 nfnetlink_rcv_msg+0xbcd/0x13f0 net/netfilter/nfnetlink.c:297
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2501
 nfnetlink_rcv+0x1ac/0x420 net/netfilter/nfnetlink.c:655
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x543/0x7f0 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x917/0xe10 net/netlink/af_netlink.c:1921
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:734
 ____sys_sendmsg+0x6eb/0x810 net/socket.c:2460
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2514
 __sys_sendmsg net/socket.c:2543 [inline]
 __do_sys_sendmsg net/socket.c:2552 [inline]
 __se_sys_sendmsg net/socket.c:2550 [inline]
 __x64_sys_sendmsg+0x132/0x220 net/socket.c:2550
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff888051af7500
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 56 bytes to the right of
 128-byte region [ffff888051af7500, ffff888051af7580)

The buggy address belongs to the physical page:
page:ffffea000146bdc0 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888051af7100 pfn:0x51af7
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0001ed5e48 ffffea0001cf4b08 ffff888010c418c0
raw: ffff888051af7100 000000000010000b 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 7027, tgid 7027 (cmp), ts 227162348638, free_ts 227160439771
 prep_new_page mm/page_alloc.c:2441 [inline]
 get_page_from_freelist+0xba2/0x3e00 mm/page_alloc.c:4182
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5408
 __alloc_pages_node include/linux/gfp.h:587 [inline]
 alloc_slab_page mm/slub.c:1801 [inline]
 allocate_slab+0x80/0x3c0 mm/slub.c:1944
 new_slab mm/slub.c:2004 [inline]
 ___slab_alloc+0x8df/0xf20 mm/slub.c:3005
 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3092
 slab_alloc_node mm/slub.c:3183 [inline]
 __kmalloc_node+0x2cb/0x390 mm/slub.c:4458
 kmalloc_array_node include/linux/slab.h:676 [inline]
 kcalloc_node include/linux/slab.h:681 [inline]
 memcg_alloc_slab_cgroups+0x8b/0x140 mm/memcontrol.c:2810
 account_slab mm/slab.h:652 [inline]
 allocate_slab+0x2c9/0x3c0 mm/slub.c:1960
 new_slab mm/slub.c:2004 [inline]
 ___slab_alloc+0x8df/0xf20 mm/slub.c:3005
 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3092
 slab_alloc_node mm/slub.c:3183 [inline]
 slab_alloc mm/slub.c:3225 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3232 [inline]
 kmem_cache_alloc+0x360/0x3b0 mm/slub.c:3242
 vm_area_dup+0x88/0x3f0 kernel/fork.c:467
 __split_vma+0xa5/0x550 mm/mmap.c:2712
 split_vma+0x95/0xd0 mm/mmap.c:2770
 mprotect_fixup+0x72d/0x950 mm/mprotect.c:494
 do_mprotect_pkey+0x532/0x980 mm/mprotect.c:650
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1356 [inline]
 free_pcp_prepare+0x549/0xd20 mm/page_alloc.c:1406
 free_unref_page_prepare mm/page_alloc.c:3328 [inline]
 free_unref_page+0x19/0x6a0 mm/page_alloc.c:3423
 __vunmap+0x85d/0xd30 mm/vmalloc.c:2667
 free_work+0x58/0x70 mm/vmalloc.c:97
 process_one_work+0x996/0x1610 kernel/workqueue.c:2289
 worker_thread+0x665/0x1080 kernel/workqueue.c:2436
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

Memory state around the buggy address:
 ffff888051af7480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888051af7500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc
>ffff888051af7580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                        ^
 ffff888051af7600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888051af7680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
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[PATCH nf-next] netfilter: cttimeout: fix slab-out-of-bounds read in cttimeout_net_exit

[Florian Westphal]

syzbot reports:
BUG: KASAN: slab-out-of-bounds in __list_del_entry_valid+0xcc/0xf0 lib/list_debug.c:42
[..]
 list_del include/linux/list.h:148 [inline]
 cttimeout_net_exit+0x211/0x540 net/netfilter/nfnetlink_cttimeout.c:617

No reproducer so far. Looking at recent changes in this area
its clear that the free_head must not be at the end of the
structure because nf_ct_timeout structure has variable size.

Reported-by: <syzbot+92968395eedbdbd3617d@syzkaller.appspotmail.com>
Fixes: 78222bacfca9 ("netfilter: cttimeout: decouple unlink and free on netns destruction")
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/nfnetlink_cttimeout.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c
index f069c24c6146..af15102bc696 100644
--- a/net/netfilter/nfnetlink_cttimeout.c
+++ b/net/netfilter/nfnetlink_cttimeout.c
@@ -35,12 +35,13 @@ static unsigned int nfct_timeout_id __read_mostly;
 
 struct ctnl_timeout {
 	struct list_head	head;
+	struct list_head	free_head;
 	struct rcu_head		rcu_head;
 	refcount_t		refcnt;
 	char			name[CTNL_TIMEOUT_NAME_MAX];
-	struct nf_ct_timeout	timeout;
 
-	struct list_head	free_head;
+	/* must be at the end */
+	struct nf_ct_timeout	timeout;
 };
 
 struct nfct_timeout_pernet {
-- 
2.35.1

Re: [PATCH nf-next] netfilter: cttimeout: fix slab-out-of-bounds read in cttimeout_net_exit

[Pablo Neira Ayuso]

On Tue, May 17, 2022 at 10:50:36PM +0200, Florian Westphal wrote:
> syzbot reports:
> BUG: KASAN: slab-out-of-bounds in __list_del_entry_valid+0xcc/0xf0 lib/list_debug.c:42
> [..]
>  list_del include/linux/list.h:148 [inline]
>  cttimeout_net_exit+0x211/0x540 net/netfilter/nfnetlink_cttimeout.c:617
> 
> No reproducer so far. Looking at recent changes in this area
> its clear that the free_head must not be at the end of the
> structure because nf_ct_timeout structure has variable size.

Applied, thanks

Re: [syzbot] KASAN: slab-out-of-bounds Read in cttimeout_net_exit

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    6ac6dc746d70 Merge branch 'mlx5-next' of git://git.kernel...
git tree:       net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=15095107f00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=20ac3e0ebf0db3bd
dashboard link: https://syzkaller.appspot.com/bug?extid=92968395eedbdbd3617d
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12e777bff00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12613a87f00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+92968395eedbdbd3617d@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 11 Comm: kworker/u4:1 Not tainted 5.19.0-rc1-syzkaller-00373-g6ac6dc746d70 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
RIP: 0010:__list_del_entry_valid+0x81/0xf0 lib/list_debug.c:51
Code: 0f 84 b5 a6 41 05 48 b8 22 01 00 00 00 00 ad de 49 39 c4 0f 84 b6 a6 41 05 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 75 51 49 8b 14 24 48 39 ea 0f 85 6a a6 41 05 49 8d 7d
RSP: 0018:ffffc90000107bc0 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88801759b310 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff879e16e1 RDI: ffff88801759b328
RBP: ffff88801759b320 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff88801759b328
FS:  0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5555f6a01d CR3: 0000000074e46000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __list_del_entry include/linux/list.h:134 [inline]
 list_del include/linux/list.h:148 [inline]
 cttimeout_net_exit+0x211/0x540 net/netfilter/nfnetlink_cttimeout.c:618
 ops_exit_list+0xb0/0x170 net/core/net_namespace.c:162
 cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:594
 process_one_work+0x996/0x1610 kernel/workqueue.c:2289
 worker_thread+0x665/0x1080 kernel/workqueue.c:2436
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__list_del_entry_valid+0x81/0xf0 lib/list_debug.c:51
Code: 0f 84 b5 a6 41 05 48 b8 22 01 00 00 00 00 ad de 49 39 c4 0f 84 b6 a6 41 05 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 75 51 49 8b 14 24 48 39 ea 0f 85 6a a6 41 05 49 8d 7d
RSP: 0018:ffffc90000107bc0 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88801759b310 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff879e16e1 RDI: ffff88801759b328
RBP: ffff88801759b320 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff88801759b328
FS:  0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5555f6a01d CR3: 0000000025f1e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	0f 84 b5 a6 41 05    	je     0x541a6bb
   6:	48 b8 22 01 00 00 00 	movabs $0xdead000000000122,%rax
   d:	00 ad de
  10:	49 39 c4             	cmp    %rax,%r12
  13:	0f 84 b6 a6 41 05    	je     0x541a6cf
  19:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  20:	fc ff df
  23:	4c 89 e2             	mov    %r12,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2e:	75 51                	jne    0x81
  30:	49 8b 14 24          	mov    (%r12),%rdx
  34:	48 39 ea             	cmp    %rbp,%rdx
  37:	0f 85 6a a6 41 05    	jne    0x541a6a7
  3d:	49                   	rex.WB
  3e:	8d                   	.byte 0x8d
  3f:	7d                   	.byte 0x7d

[PATCH nf] netfilter: cttimeout: fix slab-out-of-bounds read typo in cttimeout_net_exit

[Florian Westphal]

syzbot reports:
  BUG: KASAN: slab-out-of-bounds in __list_del_entry_valid+0xcc/0xf0 lib/list_debug.c:42
  [..]
  list_del include/linux/list.h:148 [inline]
  cttimeout_net_exit+0x211/0x540 net/netfilter/nfnetlink_cttimeout.c:617

Problem is the wrong name of the list member, so container_of yields
incorrect onj address.

Reported-by: <syzbot+92968395eedbdbd3617d@syzkaller.appspotmail.com>
Fixes: 78222bacfca9 ("netfilter: cttimeout: decouple unlink and free on netns destruction")
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/nfnetlink_cttimeout.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c
index af15102bc696..f466af4f8531 100644
--- a/net/netfilter/nfnetlink_cttimeout.c
+++ b/net/netfilter/nfnetlink_cttimeout.c
@@ -614,7 +614,7 @@ static void __net_exit cttimeout_net_exit(struct net *net)
 
 	nf_ct_untimeout(net, NULL);
 
-	list_for_each_entry_safe(cur, tmp, &pernet->nfct_timeout_freelist, head) {
+	list_for_each_entry_safe(cur, tmp, &pernet->nfct_timeout_freelist, free_head) {
 		list_del(&cur->free_head);
 
 		if (refcount_dec_and_test(&cur->refcnt))
-- 
2.35.1