[PATCH] ipvs: Fix use-after-free in ip_vs_in

[PATCH] ipvs: Fix use-after-free in ip_vs_in

[YueHaibing]

BUG: KASAN: use-after-free in ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
Read of size 4 at addr ffff8881e9b26e2c by task sshd/5603

CPU: 0 PID: 5603 Comm: sshd Not tainted 4.19.39+ #30
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
Call Trace:
 dump_stack+0x71/0xab
 print_address_description+0x6a/0x270
 kasan_report+0x179/0x2c0
 ? ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
 ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
 ? tcp_in_window+0xfe0/0xfe0 [nf_conntrack]
 ? ip_vs_in_icmp+0xcc0/0xcc0 [ip_vs]
 ? ipt_do_table+0x4f1/0xad0 [ip_tables]
 ? ip_vs_out+0x126/0x8f0 [ip_vs]
 ? common_interrupt+0xa/0xf
 ip_vs_in+0xd8/0x170 [ip_vs]
 ? ip_vs_in.part.29+0xd20/0xd20 [ip_vs]
 ? nf_nat_ipv4_fn+0x21/0xc0 [nf_nat_ipv4]
 ? nf_nat_packet+0x4b/0x90 [nf_nat]
 ? nf_nat_ipv4_local_fn+0xf9/0x160 [nf_nat_ipv4]
 ? ip_vs_remote_request4+0x50/0x50 [ip_vs]
 nf_hook_slow+0x5f/0xe0
 ? sock_write_iter+0x121/0x1c0
 __ip_local_out+0x1d5/0x250
 ? ip_finish_output+0x430/0x430
 ? ip_forward_options+0x2d0/0x2d0
 ? ip_copy_addrs+0x2d/0x40
 ? __ip_queue_xmit+0x2ca/0x730
 ip_local_out+0x19/0x60
 __tcp_transmit_skb+0xba1/0x14f0
 ? __tcp_select_window+0x330/0x330
 ? pvclock_clocksource_read+0xd1/0x180
 ? kvm_sched_clock_read+0xd/0x20
 ? sched_clock+0x5/0x10
 ? sched_clock_cpu+0x18/0x100
 tcp_write_xmit+0x41f/0x1ed0
 ? _copy_from_iter_full+0xca/0x340
 __tcp_push_pending_frames+0x52/0x140
 tcp_sendmsg_locked+0x787/0x1600
 ? __wake_up_common_lock+0x80/0x130
 ? tcp_sendpage+0x60/0x60
 ? remove_wait_queue+0x84/0xb0
 ? mutex_unlock+0x1d/0x40
 ? n_tty_read+0x4f7/0xd20
 ? check_stack_object+0x21/0x60
 ? inet_sk_set_state+0xb0/0xb0
 tcp_sendmsg+0x27/0x40
 sock_sendmsg+0x6d/0x80
 sock_write_iter+0x121/0x1c0
 ? sock_sendmsg+0x80/0x80
 ? ldsem_up_read+0x13/0x40
 ? iov_iter_init+0x77/0xb0
 __vfs_write+0x23e/0x370
 ? kernel_read+0xa0/0xa0
 ? do_vfs_ioctl+0x134/0x900
 ? __set_current_blocked+0x7e/0x90
 ? __audit_syscall_entry+0x18e/0x1f0
 ? ktime_get_coarse_real_ts64+0x51/0x70
 vfs_write+0xe7/0x230
 ksys_write+0xa1/0x120
 ? __ia32_sys_read+0x50/0x50
 ? __audit_syscall_exit+0x3ce/0x450
 do_syscall_64+0x73/0x200
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7ff6f6147c60
Code: 73 01 c3 48 8b 0d 28 12 2d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 5d 73 2d 00 00 75 10 b8 01 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83
RSP: 002b:00007ffd772ead18 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000034 RCX: 00007ff6f6147c60
RDX: 0000000000000034 RSI: 000055df30a31270 RDI: 0000000000000003
RBP: 000055df30a31270 R08: 0000000000000000 R09: 0000000000000000
R10: 00007ffd772ead70 R11: 0000000000000246 R12: 00007ffd772ead74
R13: 00007ffd772eae20 R14: 00007ffd772eae24 R15: 000055df2f12ddc0

Allocated by task 6052:
 kasan_kmalloc+0xa0/0xd0
 __kmalloc+0x10a/0x220
 ops_init+0x97/0x190
 register_pernet_operations+0x1ac/0x360
 register_pernet_subsys+0x24/0x40
 0xffffffffc0ea016d
 do_one_initcall+0x8b/0x253
 do_init_module+0xe3/0x335
 load_module+0x2fc0/0x3890
 __do_sys_finit_module+0x192/0x1c0
 do_syscall_64+0x73/0x200
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 6067:
 __kasan_slab_free+0x130/0x180
 kfree+0x90/0x1a0
 ops_free_list.part.7+0xa6/0xc0
 unregister_pernet_operations+0x18b/0x1f0
 unregister_pernet_subsys+0x1d/0x30
 ip_vs_cleanup+0x1d/0xd2f [ip_vs]
 __x64_sys_delete_module+0x20c/0x300
 do_syscall_64+0x73/0x200
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8881e9b26600 which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 2092 bytes inside of 4096-byte region [ffff8881e9b26600, ffff8881e9b27600)
The buggy address belongs to the page:
page:ffffea0007a6c800 count:1 mapcount:0 mapping:ffff888107c0e600 index:0x0 compound_mapcount: 0
flags: 0x17ffffc0008100(slab|head)
raw: 0017ffffc0008100 dead000000000100 dead000000000200 ffff888107c0e600
raw: 0000000000000000 0000000080070007 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881e9b26d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881e9b26d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881e9b26e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff8881e9b26e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881e9b26f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

while unregistering ipvs module, ops_free_list calls
__ip_vs_cleanup, then nf_unregister_net_hooks be called to
do remove nf hook entries. It need a RCU period to finish,
however net->ipvs is set to NULL immediately, which will
trigger NULL pointer dereference when a packet is hooked
and handled by ip_vs_in where net->ipvs is dereferenced.

Another scene is ops_free_list call ops_free to free the
net_generic directly while __ip_vs_cleanup finished, then
calling ip_vs_in will triggers use-after-free.

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: efe41606184e ("ipvs: convert to use pernet nf_hook api")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
---
 net/netfilter/ipvs/ip_vs_core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index 1445755..33205db 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -2320,6 +2320,7 @@ static void __net_exit __ip_vs_cleanup(struct net *net)
 	ip_vs_control_net_cleanup(ipvs);
 	ip_vs_estimator_net_cleanup(ipvs);
 	IP_VS_DBG(2, "ipvs netns %d released\n", ipvs->gen);
+	synchronize_net();
 	net->ipvs = NULL;
 }
 
-- 
2.7.4

Re: [PATCH] ipvs: Fix use-after-free in ip_vs_in

[Julian Anastasov]

	Hello,

On Wed, 15 May 2019, YueHaibing wrote:

> BUG: KASAN: use-after-free in ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
> Read of size 4 at addr ffff8881e9b26e2c by task sshd/5603
> 
> CPU: 0 PID: 5603 Comm: sshd Not tainted 4.19.39+ #30
> Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
> Call Trace:
>  dump_stack+0x71/0xab
>  print_address_description+0x6a/0x270
>  kasan_report+0x179/0x2c0
>  ? ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
>  ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
>  ? tcp_in_window+0xfe0/0xfe0 [nf_conntrack]
>  ? ip_vs_in_icmp+0xcc0/0xcc0 [ip_vs]
>  ? ipt_do_table+0x4f1/0xad0 [ip_tables]
>  ? ip_vs_out+0x126/0x8f0 [ip_vs]
>  ? common_interrupt+0xa/0xf
>  ip_vs_in+0xd8/0x170 [ip_vs]
>  ? ip_vs_in.part.29+0xd20/0xd20 [ip_vs]
>  ? nf_nat_ipv4_fn+0x21/0xc0 [nf_nat_ipv4]
>  ? nf_nat_packet+0x4b/0x90 [nf_nat]
>  ? nf_nat_ipv4_local_fn+0xf9/0x160 [nf_nat_ipv4]
>  ? ip_vs_remote_request4+0x50/0x50 [ip_vs]
>  nf_hook_slow+0x5f/0xe0
>  ? sock_write_iter+0x121/0x1c0
>  __ip_local_out+0x1d5/0x250
>  ? ip_finish_output+0x430/0x430
>  ? ip_forward_options+0x2d0/0x2d0
>  ? ip_copy_addrs+0x2d/0x40
>  ? __ip_queue_xmit+0x2ca/0x730
>  ip_local_out+0x19/0x60
>  __tcp_transmit_skb+0xba1/0x14f0
>  ? __tcp_select_window+0x330/0x330
>  ? pvclock_clocksource_read+0xd1/0x180
>  ? kvm_sched_clock_read+0xd/0x20
>  ? sched_clock+0x5/0x10
>  ? sched_clock_cpu+0x18/0x100
>  tcp_write_xmit+0x41f/0x1ed0
>  ? _copy_from_iter_full+0xca/0x340
>  __tcp_push_pending_frames+0x52/0x140
>  tcp_sendmsg_locked+0x787/0x1600
>  ? __wake_up_common_lock+0x80/0x130
>  ? tcp_sendpage+0x60/0x60
>  ? remove_wait_queue+0x84/0xb0
>  ? mutex_unlock+0x1d/0x40
>  ? n_tty_read+0x4f7/0xd20
>  ? check_stack_object+0x21/0x60
>  ? inet_sk_set_state+0xb0/0xb0
>  tcp_sendmsg+0x27/0x40
>  sock_sendmsg+0x6d/0x80
>  sock_write_iter+0x121/0x1c0
>  ? sock_sendmsg+0x80/0x80
>  ? ldsem_up_read+0x13/0x40
>  ? iov_iter_init+0x77/0xb0
>  __vfs_write+0x23e/0x370
>  ? kernel_read+0xa0/0xa0
>  ? do_vfs_ioctl+0x134/0x900
>  ? __set_current_blocked+0x7e/0x90
>  ? __audit_syscall_entry+0x18e/0x1f0
>  ? ktime_get_coarse_real_ts64+0x51/0x70
>  vfs_write+0xe7/0x230
>  ksys_write+0xa1/0x120
>  ? __ia32_sys_read+0x50/0x50
>  ? __audit_syscall_exit+0x3ce/0x450
>  do_syscall_64+0x73/0x200
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x7ff6f6147c60
> Code: 73 01 c3 48 8b 0d 28 12 2d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 5d 73 2d 00 00 75 10 b8 01 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83
> RSP: 002b:00007ffd772ead18 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 0000000000000034 RCX: 00007ff6f6147c60
> RDX: 0000000000000034 RSI: 000055df30a31270 RDI: 0000000000000003
> RBP: 000055df30a31270 R08: 0000000000000000 R09: 0000000000000000
> R10: 00007ffd772ead70 R11: 0000000000000246 R12: 00007ffd772ead74
> R13: 00007ffd772eae20 R14: 00007ffd772eae24 R15: 000055df2f12ddc0
> 
> Allocated by task 6052:
>  kasan_kmalloc+0xa0/0xd0
>  __kmalloc+0x10a/0x220
>  ops_init+0x97/0x190
>  register_pernet_operations+0x1ac/0x360
>  register_pernet_subsys+0x24/0x40
>  0xffffffffc0ea016d
>  do_one_initcall+0x8b/0x253
>  do_init_module+0xe3/0x335
>  load_module+0x2fc0/0x3890
>  __do_sys_finit_module+0x192/0x1c0
>  do_syscall_64+0x73/0x200
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> Freed by task 6067:
>  __kasan_slab_free+0x130/0x180
>  kfree+0x90/0x1a0
>  ops_free_list.part.7+0xa6/0xc0
>  unregister_pernet_operations+0x18b/0x1f0
>  unregister_pernet_subsys+0x1d/0x30
>  ip_vs_cleanup+0x1d/0xd2f [ip_vs]
>  __x64_sys_delete_module+0x20c/0x300
>  do_syscall_64+0x73/0x200
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> The buggy address belongs to the object at ffff8881e9b26600 which belongs to the cache kmalloc-4096 of size 4096
> The buggy address is located 2092 bytes inside of 4096-byte region [ffff8881e9b26600, ffff8881e9b27600)
> The buggy address belongs to the page:
> page:ffffea0007a6c800 count:1 mapcount:0 mapping:ffff888107c0e600 index:0x0 compound_mapcount: 0
> flags: 0x17ffffc0008100(slab|head)
> raw: 0017ffffc0008100 dead000000000100 dead000000000200 ffff888107c0e600
> raw: 0000000000000000 0000000080070007 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
> 
> Memory state around the buggy address:
>  ffff8881e9b26d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8881e9b26d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >ffff8881e9b26e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                                   ^
>  ffff8881e9b26e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8881e9b26f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> 
> while unregistering ipvs module, ops_free_list calls
> __ip_vs_cleanup, then nf_unregister_net_hooks be called to
> do remove nf hook entries. It need a RCU period to finish,
> however net->ipvs is set to NULL immediately, which will
> trigger NULL pointer dereference when a packet is hooked
> and handled by ip_vs_in where net->ipvs is dereferenced.
> 
> Another scene is ops_free_list call ops_free to free the
> net_generic directly while __ip_vs_cleanup finished, then
> calling ip_vs_in will triggers use-after-free.
> 
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Fixes: efe41606184e ("ipvs: convert to use pernet nf_hook api")
> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
> ---
>  net/netfilter/ipvs/ip_vs_core.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> index 1445755..33205db 100644
> --- a/net/netfilter/ipvs/ip_vs_core.c
> +++ b/net/netfilter/ipvs/ip_vs_core.c
> @@ -2320,6 +2320,7 @@ static void __net_exit __ip_vs_cleanup(struct net *net)
>  	ip_vs_control_net_cleanup(ipvs);
>  	ip_vs_estimator_net_cleanup(ipvs);
>  	IP_VS_DBG(2, "ipvs netns %d released\n", ipvs->gen);
> +	synchronize_net();

	Grace period in net_exit handler should be avoided.
It can be added to ip_vs_cleanup() but may be we have to
reorder the operations, so that we can have single grace
period. Note that ip_vs_conn_cleanup() already includes
rcu_barrier() and we can use it to split the cleanups to
two steps: 1: unregister hooks (__ip_vs_dev_cleanup) to
stop traffic and 2: cleanups when traffic is stopped.

	Note that the problem should be only when module
is removed, the case with netns exit in cleanup_net()
should not cause problem.

	I'll have more time this weekend to reorganize the
code...

>  	net->ipvs = NULL;
>  }
>  
> -- 
> 2.7.4

Regards

--
Julian Anastasov <ja@ssi.bg>

Re: [PATCH] ipvs: Fix use-after-free in ip_vs_in

[Julian Anastasov]

	Hello,

On Wed, 15 May 2019, YueHaibing wrote:

> BUG: KASAN: use-after-free in ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
> Read of size 4 at addr ffff8881e9b26e2c by task sshd/5603
> 
> CPU: 0 PID: 5603 Comm: sshd Not tainted 4.19.39+ #30
> Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
> Call Trace:
>  dump_stack+0x71/0xab
>  print_address_description+0x6a/0x270
>  kasan_report+0x179/0x2c0
>  ? ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
>  ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
>  ? tcp_in_window+0xfe0/0xfe0 [nf_conntrack]
>  ? ip_vs_in_icmp+0xcc0/0xcc0 [ip_vs]
>  ? ipt_do_table+0x4f1/0xad0 [ip_tables]
>  ? ip_vs_out+0x126/0x8f0 [ip_vs]
>  ? common_interrupt+0xa/0xf
>  ip_vs_in+0xd8/0x170 [ip_vs]
>  ? ip_vs_in.part.29+0xd20/0xd20 [ip_vs]
>  ? nf_nat_ipv4_fn+0x21/0xc0 [nf_nat_ipv4]
>  ? nf_nat_packet+0x4b/0x90 [nf_nat]
>  ? nf_nat_ipv4_local_fn+0xf9/0x160 [nf_nat_ipv4]
>  ? ip_vs_remote_request4+0x50/0x50 [ip_vs]
>  nf_hook_slow+0x5f/0xe0
>  ? sock_write_iter+0x121/0x1c0
>  __ip_local_out+0x1d5/0x250
>  ? ip_finish_output+0x430/0x430
>  ? ip_forward_options+0x2d0/0x2d0
>  ? ip_copy_addrs+0x2d/0x40
>  ? __ip_queue_xmit+0x2ca/0x730
>  ip_local_out+0x19/0x60
>  __tcp_transmit_skb+0xba1/0x14f0
>  ? __tcp_select_window+0x330/0x330
>  ? pvclock_clocksource_read+0xd1/0x180
>  ? kvm_sched_clock_read+0xd/0x20
>  ? sched_clock+0x5/0x10
>  ? sched_clock_cpu+0x18/0x100
>  tcp_write_xmit+0x41f/0x1ed0
>  ? _copy_from_iter_full+0xca/0x340
>  __tcp_push_pending_frames+0x52/0x140
>  tcp_sendmsg_locked+0x787/0x1600
>  ? __wake_up_common_lock+0x80/0x130
>  ? tcp_sendpage+0x60/0x60
>  ? remove_wait_queue+0x84/0xb0
>  ? mutex_unlock+0x1d/0x40
>  ? n_tty_read+0x4f7/0xd20
>  ? check_stack_object+0x21/0x60
>  ? inet_sk_set_state+0xb0/0xb0
>  tcp_sendmsg+0x27/0x40
>  sock_sendmsg+0x6d/0x80
>  sock_write_iter+0x121/0x1c0
>  ? sock_sendmsg+0x80/0x80
>  ? ldsem_up_read+0x13/0x40
>  ? iov_iter_init+0x77/0xb0
>  __vfs_write+0x23e/0x370
>  ? kernel_read+0xa0/0xa0
>  ? do_vfs_ioctl+0x134/0x900
>  ? __set_current_blocked+0x7e/0x90
>  ? __audit_syscall_entry+0x18e/0x1f0
>  ? ktime_get_coarse_real_ts64+0x51/0x70
>  vfs_write+0xe7/0x230
>  ksys_write+0xa1/0x120
>  ? __ia32_sys_read+0x50/0x50
>  ? __audit_syscall_exit+0x3ce/0x450
>  do_syscall_64+0x73/0x200
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x7ff6f6147c60
> Code: 73 01 c3 48 8b 0d 28 12 2d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 5d 73 2d 00 00 75 10 b8 01 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83
> RSP: 002b:00007ffd772ead18 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 0000000000000034 RCX: 00007ff6f6147c60
> RDX: 0000000000000034 RSI: 000055df30a31270 RDI: 0000000000000003
> RBP: 000055df30a31270 R08: 0000000000000000 R09: 0000000000000000
> R10: 00007ffd772ead70 R11: 0000000000000246 R12: 00007ffd772ead74
> R13: 00007ffd772eae20 R14: 00007ffd772eae24 R15: 000055df2f12ddc0
> 
> Allocated by task 6052:
>  kasan_kmalloc+0xa0/0xd0
>  __kmalloc+0x10a/0x220
>  ops_init+0x97/0x190
>  register_pernet_operations+0x1ac/0x360
>  register_pernet_subsys+0x24/0x40
>  0xffffffffc0ea016d
>  do_one_initcall+0x8b/0x253
>  do_init_module+0xe3/0x335
>  load_module+0x2fc0/0x3890
>  __do_sys_finit_module+0x192/0x1c0
>  do_syscall_64+0x73/0x200
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> Freed by task 6067:
>  __kasan_slab_free+0x130/0x180
>  kfree+0x90/0x1a0
>  ops_free_list.part.7+0xa6/0xc0
>  unregister_pernet_operations+0x18b/0x1f0
>  unregister_pernet_subsys+0x1d/0x30
>  ip_vs_cleanup+0x1d/0xd2f [ip_vs]
>  __x64_sys_delete_module+0x20c/0x300
>  do_syscall_64+0x73/0x200
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> The buggy address belongs to the object at ffff8881e9b26600 which belongs to the cache kmalloc-4096 of size 4096
> The buggy address is located 2092 bytes inside of 4096-byte region [ffff8881e9b26600, ffff8881e9b27600)
> The buggy address belongs to the page:
> page:ffffea0007a6c800 count:1 mapcount:0 mapping:ffff888107c0e600 index:0x0 compound_mapcount: 0
> flags: 0x17ffffc0008100(slab|head)
> raw: 0017ffffc0008100 dead000000000100 dead000000000200 ffff888107c0e600
> raw: 0000000000000000 0000000080070007 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
> 
> Memory state around the buggy address:
>  ffff8881e9b26d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8881e9b26d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >ffff8881e9b26e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                                   ^
>  ffff8881e9b26e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8881e9b26f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> 
> while unregistering ipvs module, ops_free_list calls
> __ip_vs_cleanup, then nf_unregister_net_hooks be called to
> do remove nf hook entries. It need a RCU period to finish,
> however net->ipvs is set to NULL immediately, which will
> trigger NULL pointer dereference when a packet is hooked
> and handled by ip_vs_in where net->ipvs is dereferenced.
> 
> Another scene is ops_free_list call ops_free to free the
> net_generic directly while __ip_vs_cleanup finished, then
> calling ip_vs_in will triggers use-after-free.

	OK, can you instead test and post a patch that moves
nf_unregister_net_hooks from __ip_vs_cleanup() to
__ip_vs_dev_cleanup()? You can add commit efe41606184e
in Fixes line. There is rcu_barrier() in unregister_pernet_device ->
unregister_pernet_operations that will do the needed grace
period.

	In a followup patch for net-next I'll drop the
ipvs->enable flag and will move the nf_register_net_hooks()
call to ip_vs_add_service() just before the 'svc = kzalloc'
part. So, for now you do not need to move nf_register_net_hooks.
As result, hooks will be registered when there are IPVS rules.

> Reported-by: Hulk Robot <hulkci@huawei.com>
> Fixes: efe41606184e ("ipvs: convert to use pernet nf_hook api")
> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
> ---
>  net/netfilter/ipvs/ip_vs_core.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> index 1445755..33205db 100644
> --- a/net/netfilter/ipvs/ip_vs_core.c
> +++ b/net/netfilter/ipvs/ip_vs_core.c
> @@ -2320,6 +2320,7 @@ static void __net_exit __ip_vs_cleanup(struct net *net)
>  	ip_vs_control_net_cleanup(ipvs);
>  	ip_vs_estimator_net_cleanup(ipvs);
>  	IP_VS_DBG(2, "ipvs netns %d released\n", ipvs->gen);
> +	synchronize_net();
>  	net->ipvs = NULL;
>  }

Regards

--
Julian Anastasov <ja@ssi.bg>

Re: [PATCH] ipvs: Fix use-after-free in ip_vs_in

[YueHaibing]

On 2019/5/17 15:30, Julian Anastasov wrote:
> 
> 	Hello,
> 
> On Wed, 15 May 2019, YueHaibing wrote:
> 
>> BUG: KASAN: use-after-free in ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
>> Read of size 4 at addr ffff8881e9b26e2c by task sshd/5603
>>
>> CPU: 0 PID: 5603 Comm: sshd Not tainted 4.19.39+ #30
>> Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
>> Call Trace:
>>  dump_stack+0x71/0xab
>>  print_address_description+0x6a/0x270
>>  kasan_report+0x179/0x2c0
>>  ? ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
>>  ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
>>  ? tcp_in_window+0xfe0/0xfe0 [nf_conntrack]
>>  ? ip_vs_in_icmp+0xcc0/0xcc0 [ip_vs]
>>  ? ipt_do_table+0x4f1/0xad0 [ip_tables]
>>  ? ip_vs_out+0x126/0x8f0 [ip_vs]
>>  ? common_interrupt+0xa/0xf
>>  ip_vs_in+0xd8/0x170 [ip_vs]
>>  ? ip_vs_in.part.29+0xd20/0xd20 [ip_vs]
>>  ? nf_nat_ipv4_fn+0x21/0xc0 [nf_nat_ipv4]
>>  ? nf_nat_packet+0x4b/0x90 [nf_nat]
>>  ? nf_nat_ipv4_local_fn+0xf9/0x160 [nf_nat_ipv4]
>>  ? ip_vs_remote_request4+0x50/0x50 [ip_vs]
>>  nf_hook_slow+0x5f/0xe0
>>  ? sock_write_iter+0x121/0x1c0
>>  __ip_local_out+0x1d5/0x250
>>  ? ip_finish_output+0x430/0x430
>>  ? ip_forward_options+0x2d0/0x2d0
>>  ? ip_copy_addrs+0x2d/0x40
>>  ? __ip_queue_xmit+0x2ca/0x730
>>  ip_local_out+0x19/0x60
>>  __tcp_transmit_skb+0xba1/0x14f0
>>  ? __tcp_select_window+0x330/0x330
>>  ? pvclock_clocksource_read+0xd1/0x180
>>  ? kvm_sched_clock_read+0xd/0x20
>>  ? sched_clock+0x5/0x10
>>  ? sched_clock_cpu+0x18/0x100
>>  tcp_write_xmit+0x41f/0x1ed0
>>  ? _copy_from_iter_full+0xca/0x340
>>  __tcp_push_pending_frames+0x52/0x140
>>  tcp_sendmsg_locked+0x787/0x1600
>>  ? __wake_up_common_lock+0x80/0x130
>>  ? tcp_sendpage+0x60/0x60
>>  ? remove_wait_queue+0x84/0xb0
>>  ? mutex_unlock+0x1d/0x40
>>  ? n_tty_read+0x4f7/0xd20
>>  ? check_stack_object+0x21/0x60
>>  ? inet_sk_set_state+0xb0/0xb0
>>  tcp_sendmsg+0x27/0x40
>>  sock_sendmsg+0x6d/0x80
>>  sock_write_iter+0x121/0x1c0
>>  ? sock_sendmsg+0x80/0x80
>>  ? ldsem_up_read+0x13/0x40
>>  ? iov_iter_init+0x77/0xb0
>>  __vfs_write+0x23e/0x370
>>  ? kernel_read+0xa0/0xa0
>>  ? do_vfs_ioctl+0x134/0x900
>>  ? __set_current_blocked+0x7e/0x90
>>  ? __audit_syscall_entry+0x18e/0x1f0
>>  ? ktime_get_coarse_real_ts64+0x51/0x70
>>  vfs_write+0xe7/0x230
>>  ksys_write+0xa1/0x120
>>  ? __ia32_sys_read+0x50/0x50
>>  ? __audit_syscall_exit+0x3ce/0x450
>>  do_syscall_64+0x73/0x200
>>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>> RIP: 0033:0x7ff6f6147c60
>> Code: 73 01 c3 48 8b 0d 28 12 2d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 5d 73 2d 00 00 75 10 b8 01 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83
>> RSP: 002b:00007ffd772ead18 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
>> RAX: ffffffffffffffda RBX: 0000000000000034 RCX: 00007ff6f6147c60
>> RDX: 0000000000000034 RSI: 000055df30a31270 RDI: 0000000000000003
>> RBP: 000055df30a31270 R08: 0000000000000000 R09: 0000000000000000
>> R10: 00007ffd772ead70 R11: 0000000000000246 R12: 00007ffd772ead74
>> R13: 00007ffd772eae20 R14: 00007ffd772eae24 R15: 000055df2f12ddc0
>>
>> Allocated by task 6052:
>>  kasan_kmalloc+0xa0/0xd0
>>  __kmalloc+0x10a/0x220
>>  ops_init+0x97/0x190
>>  register_pernet_operations+0x1ac/0x360
>>  register_pernet_subsys+0x24/0x40
>>  0xffffffffc0ea016d
>>  do_one_initcall+0x8b/0x253
>>  do_init_module+0xe3/0x335
>>  load_module+0x2fc0/0x3890
>>  __do_sys_finit_module+0x192/0x1c0
>>  do_syscall_64+0x73/0x200
>>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>
>> Freed by task 6067:
>>  __kasan_slab_free+0x130/0x180
>>  kfree+0x90/0x1a0
>>  ops_free_list.part.7+0xa6/0xc0
>>  unregister_pernet_operations+0x18b/0x1f0
>>  unregister_pernet_subsys+0x1d/0x30
>>  ip_vs_cleanup+0x1d/0xd2f [ip_vs]
>>  __x64_sys_delete_module+0x20c/0x300
>>  do_syscall_64+0x73/0x200
>>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>
>> The buggy address belongs to the object at ffff8881e9b26600 which belongs to the cache kmalloc-4096 of size 4096
>> The buggy address is located 2092 bytes inside of 4096-byte region [ffff8881e9b26600, ffff8881e9b27600)
>> The buggy address belongs to the page:
>> page:ffffea0007a6c800 count:1 mapcount:0 mapping:ffff888107c0e600 index:0x0 compound_mapcount: 0
>> flags: 0x17ffffc0008100(slab|head)
>> raw: 0017ffffc0008100 dead000000000100 dead000000000200 ffff888107c0e600
>> raw: 0000000000000000 0000000080070007 00000001ffffffff 0000000000000000
>> page dumped because: kasan: bad access detected
>>
>> Memory state around the buggy address:
>>  ffff8881e9b26d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>  ffff8881e9b26d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>> ffff8881e9b26e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>                                   ^
>>  ffff8881e9b26e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>  ffff8881e9b26f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>
>> while unregistering ipvs module, ops_free_list calls
>> __ip_vs_cleanup, then nf_unregister_net_hooks be called to
>> do remove nf hook entries. It need a RCU period to finish,
>> however net->ipvs is set to NULL immediately, which will
>> trigger NULL pointer dereference when a packet is hooked
>> and handled by ip_vs_in where net->ipvs is dereferenced.
>>
>> Another scene is ops_free_list call ops_free to free the
>> net_generic directly while __ip_vs_cleanup finished, then
>> calling ip_vs_in will triggers use-after-free.
> 
> 	OK, can you instead test and post a patch that moves
> nf_unregister_net_hooks from __ip_vs_cleanup() to
> __ip_vs_dev_cleanup()? You can add commit efe41606184e
> in Fixes line. There is rcu_barrier() in unregister_pernet_device ->
> unregister_pernet_operations that will do the needed grace
> period.

Ok,  I will try it later, thanks!

> 
> 	In a followup patch for net-next I'll drop the
> ipvs->enable flag and will move the nf_register_net_hooks()
> call to ip_vs_add_service() just before the 'svc = kzalloc'
> part. So, for now you do not need to move nf_register_net_hooks.
> As result, hooks will be registered when there are IPVS rules.
> 
>> Reported-by: Hulk Robot <hulkci@huawei.com>
>> Fixes: efe41606184e ("ipvs: convert to use pernet nf_hook api")
>> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
>> ---
>>  net/netfilter/ipvs/ip_vs_core.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
>> index 1445755..33205db 100644
>> --- a/net/netfilter/ipvs/ip_vs_core.c
>> +++ b/net/netfilter/ipvs/ip_vs_core.c
>> @@ -2320,6 +2320,7 @@ static void __net_exit __ip_vs_cleanup(struct net *net)
>>  	ip_vs_control_net_cleanup(ipvs);
>>  	ip_vs_estimator_net_cleanup(ipvs);
>>  	IP_VS_DBG(2, "ipvs netns %d released\n", ipvs->gen);
>> +	synchronize_net();
>>  	net->ipvs = NULL;
>>  }
> 
> Regards
> 
> --
> Julian Anastasov <ja@ssi.bg>
> 
> .
> 

[PATCH v2] ipvs: Fix use-after-free in ip_vs_in

[YueHaibing]

BUG: KASAN: use-after-free in ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
Read of size 4 at addr ffff8881e9b26e2c by task sshd/5603

CPU: 0 PID: 5603 Comm: sshd Not tainted 4.19.39+ #30
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
Call Trace:
 dump_stack+0x71/0xab
 print_address_description+0x6a/0x270
 kasan_report+0x179/0x2c0
 ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
 ip_vs_in+0xd8/0x170 [ip_vs]
 nf_hook_slow+0x5f/0xe0
 __ip_local_out+0x1d5/0x250
 ip_local_out+0x19/0x60
 __tcp_transmit_skb+0xba1/0x14f0
 tcp_write_xmit+0x41f/0x1ed0
 ? _copy_from_iter_full+0xca/0x340
 __tcp_push_pending_frames+0x52/0x140
 tcp_sendmsg_locked+0x787/0x1600
 ? tcp_sendpage+0x60/0x60
 ? inet_sk_set_state+0xb0/0xb0
 tcp_sendmsg+0x27/0x40
 sock_sendmsg+0x6d/0x80
 sock_write_iter+0x121/0x1c0
 ? sock_sendmsg+0x80/0x80
 __vfs_write+0x23e/0x370
 vfs_write+0xe7/0x230
 ksys_write+0xa1/0x120
 ? __ia32_sys_read+0x50/0x50
 ? __audit_syscall_exit+0x3ce/0x450
 do_syscall_64+0x73/0x200
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7ff6f6147c60
Code: 73 01 c3 48 8b 0d 28 12 2d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 5d 73 2d 00 00 75 10 b8 01 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83
RSP: 002b:00007ffd772ead18 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000034 RCX: 00007ff6f6147c60
RDX: 0000000000000034 RSI: 000055df30a31270 RDI: 0000000000000003
RBP: 000055df30a31270 R08: 0000000000000000 R09: 0000000000000000
R10: 00007ffd772ead70 R11: 0000000000000246 R12: 00007ffd772ead74
R13: 00007ffd772eae20 R14: 00007ffd772eae24 R15: 000055df2f12ddc0

Allocated by task 6052:
 kasan_kmalloc+0xa0/0xd0
 __kmalloc+0x10a/0x220
 ops_init+0x97/0x190
 register_pernet_operations+0x1ac/0x360
 register_pernet_subsys+0x24/0x40
 0xffffffffc0ea016d
 do_one_initcall+0x8b/0x253
 do_init_module+0xe3/0x335
 load_module+0x2fc0/0x3890
 __do_sys_finit_module+0x192/0x1c0
 do_syscall_64+0x73/0x200
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 6067:
 __kasan_slab_free+0x130/0x180
 kfree+0x90/0x1a0
 ops_free_list.part.7+0xa6/0xc0
 unregister_pernet_operations+0x18b/0x1f0
 unregister_pernet_subsys+0x1d/0x30
 ip_vs_cleanup+0x1d/0xd2f [ip_vs]
 __x64_sys_delete_module+0x20c/0x300
 do_syscall_64+0x73/0x200
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8881e9b26600 which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 2092 bytes inside of 4096-byte region [ffff8881e9b26600, ffff8881e9b27600)
The buggy address belongs to the page:
page:ffffea0007a6c800 count:1 mapcount:0 mapping:ffff888107c0e600 index:0x0 compound_mapcount: 0
flags: 0x17ffffc0008100(slab|head)
raw: 0017ffffc0008100 dead000000000100 dead000000000200 ffff888107c0e600
raw: 0000000000000000 0000000080070007 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

while unregistering ipvs module, ops_free_list calls
__ip_vs_cleanup, then nf_unregister_net_hooks be called to
do remove nf hook entries. It need a RCU period to finish,
however net->ipvs is set to NULL immediately, which will
trigger NULL pointer dereference when a packet is hooked
and handled by ip_vs_in where net->ipvs is dereferenced.

Another scene is ops_free_list call ops_free to free the
net_generic directly while __ip_vs_cleanup finished, then
calling ip_vs_in will triggers use-after-free.

This patch moves nf_unregister_net_hooks from __ip_vs_cleanup()
to __ip_vs_dev_cleanup(),  where rcu_barrier() is called by
unregister_pernet_device -> unregister_pernet_operations,
that will do the needed grace period.

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: efe41606184e ("ipvs: convert to use pernet nf_hook api")
Suggested-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
---
v2: fix by moving nf_unregister_net_hooks from __ip_vs_cleanup() to __ip_vs_dev_cleanup()
---
 net/netfilter/ipvs/ip_vs_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index 14457551bcb4..8ebf21149ec3 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -2312,7 +2312,6 @@ static void __net_exit __ip_vs_cleanup(struct net *net)
 {
 	struct netns_ipvs *ipvs = net_ipvs(net);
 
-	nf_unregister_net_hooks(net, ip_vs_ops, ARRAY_SIZE(ip_vs_ops));
 	ip_vs_service_net_cleanup(ipvs);	/* ip_vs_flush() with locks */
 	ip_vs_conn_net_cleanup(ipvs);
 	ip_vs_app_net_cleanup(ipvs);
@@ -2327,6 +2326,7 @@ static void __net_exit __ip_vs_dev_cleanup(struct net *net)
 {
 	struct netns_ipvs *ipvs = net_ipvs(net);
 	EnterFunction(2);
+	nf_unregister_net_hooks(net, ip_vs_ops, ARRAY_SIZE(ip_vs_ops));
 	ipvs->enable = 0;	/* Disable packet reception */
 	smp_wmb();
 	ip_vs_sync_net_cleanup(ipvs);
-- 
2.20.1

Re: [PATCH v2] ipvs: Fix use-after-free in ip_vs_in

[Julian Anastasov]

	Hello,

On Fri, 17 May 2019, YueHaibing wrote:

> BUG: KASAN: use-after-free in ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
> Read of size 4 at addr ffff8881e9b26e2c by task sshd/5603
> 
> CPU: 0 PID: 5603 Comm: sshd Not tainted 4.19.39+ #30
> Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
> Call Trace:
>  dump_stack+0x71/0xab
>  print_address_description+0x6a/0x270
>  kasan_report+0x179/0x2c0
>  ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
>  ip_vs_in+0xd8/0x170 [ip_vs]
>  nf_hook_slow+0x5f/0xe0
>  __ip_local_out+0x1d5/0x250
>  ip_local_out+0x19/0x60
>  __tcp_transmit_skb+0xba1/0x14f0
>  tcp_write_xmit+0x41f/0x1ed0
>  ? _copy_from_iter_full+0xca/0x340
>  __tcp_push_pending_frames+0x52/0x140
>  tcp_sendmsg_locked+0x787/0x1600
>  ? tcp_sendpage+0x60/0x60
>  ? inet_sk_set_state+0xb0/0xb0
>  tcp_sendmsg+0x27/0x40
>  sock_sendmsg+0x6d/0x80
>  sock_write_iter+0x121/0x1c0
>  ? sock_sendmsg+0x80/0x80
>  __vfs_write+0x23e/0x370
>  vfs_write+0xe7/0x230
>  ksys_write+0xa1/0x120
>  ? __ia32_sys_read+0x50/0x50
>  ? __audit_syscall_exit+0x3ce/0x450
>  do_syscall_64+0x73/0x200
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x7ff6f6147c60
> Code: 73 01 c3 48 8b 0d 28 12 2d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 5d 73 2d 00 00 75 10 b8 01 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83
> RSP: 002b:00007ffd772ead18 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 0000000000000034 RCX: 00007ff6f6147c60
> RDX: 0000000000000034 RSI: 000055df30a31270 RDI: 0000000000000003
> RBP: 000055df30a31270 R08: 0000000000000000 R09: 0000000000000000
> R10: 00007ffd772ead70 R11: 0000000000000246 R12: 00007ffd772ead74
> R13: 00007ffd772eae20 R14: 00007ffd772eae24 R15: 000055df2f12ddc0
> 
> Allocated by task 6052:
>  kasan_kmalloc+0xa0/0xd0
>  __kmalloc+0x10a/0x220
>  ops_init+0x97/0x190
>  register_pernet_operations+0x1ac/0x360
>  register_pernet_subsys+0x24/0x40
>  0xffffffffc0ea016d
>  do_one_initcall+0x8b/0x253
>  do_init_module+0xe3/0x335
>  load_module+0x2fc0/0x3890
>  __do_sys_finit_module+0x192/0x1c0
>  do_syscall_64+0x73/0x200
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> Freed by task 6067:
>  __kasan_slab_free+0x130/0x180
>  kfree+0x90/0x1a0
>  ops_free_list.part.7+0xa6/0xc0
>  unregister_pernet_operations+0x18b/0x1f0
>  unregister_pernet_subsys+0x1d/0x30
>  ip_vs_cleanup+0x1d/0xd2f [ip_vs]
>  __x64_sys_delete_module+0x20c/0x300
>  do_syscall_64+0x73/0x200
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> The buggy address belongs to the object at ffff8881e9b26600 which belongs to the cache kmalloc-4096 of size 4096
> The buggy address is located 2092 bytes inside of 4096-byte region [ffff8881e9b26600, ffff8881e9b27600)
> The buggy address belongs to the page:
> page:ffffea0007a6c800 count:1 mapcount:0 mapping:ffff888107c0e600 index:0x0 compound_mapcount: 0
> flags: 0x17ffffc0008100(slab|head)
> raw: 0017ffffc0008100 dead000000000100 dead000000000200 ffff888107c0e600
> raw: 0000000000000000 0000000080070007 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
> 
> while unregistering ipvs module, ops_free_list calls
> __ip_vs_cleanup, then nf_unregister_net_hooks be called to
> do remove nf hook entries. It need a RCU period to finish,
> however net->ipvs is set to NULL immediately, which will
> trigger NULL pointer dereference when a packet is hooked
> and handled by ip_vs_in where net->ipvs is dereferenced.
> 
> Another scene is ops_free_list call ops_free to free the
> net_generic directly while __ip_vs_cleanup finished, then
> calling ip_vs_in will triggers use-after-free.
> 
> This patch moves nf_unregister_net_hooks from __ip_vs_cleanup()
> to __ip_vs_dev_cleanup(),  where rcu_barrier() is called by
> unregister_pernet_device -> unregister_pernet_operations,
> that will do the needed grace period.
> 
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Fixes: efe41606184e ("ipvs: convert to use pernet nf_hook api")
> Suggested-by: Julian Anastasov <ja@ssi.bg>
> Signed-off-by: YueHaibing <yuehaibing@huawei.com>

	Looks good to me, thanks!

Acked-by: Julian Anastasov <ja@ssi.bg>

	It should restore the order of unregistrations before
the mentioned commit and to ensure grace period before stopping
the traffic and unregistering ipvs_core_ops where traffic is not
expected.

> ---
> v2: fix by moving nf_unregister_net_hooks from __ip_vs_cleanup() to __ip_vs_dev_cleanup()
> ---
>  net/netfilter/ipvs/ip_vs_core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> index 14457551bcb4..8ebf21149ec3 100644
> --- a/net/netfilter/ipvs/ip_vs_core.c
> +++ b/net/netfilter/ipvs/ip_vs_core.c
> @@ -2312,7 +2312,6 @@ static void __net_exit __ip_vs_cleanup(struct net *net)
>  {
>  	struct netns_ipvs *ipvs = net_ipvs(net);
>  
> -	nf_unregister_net_hooks(net, ip_vs_ops, ARRAY_SIZE(ip_vs_ops));
>  	ip_vs_service_net_cleanup(ipvs);	/* ip_vs_flush() with locks */
>  	ip_vs_conn_net_cleanup(ipvs);
>  	ip_vs_app_net_cleanup(ipvs);
> @@ -2327,6 +2326,7 @@ static void __net_exit __ip_vs_dev_cleanup(struct net *net)
>  {
>  	struct netns_ipvs *ipvs = net_ipvs(net);
>  	EnterFunction(2);
> +	nf_unregister_net_hooks(net, ip_vs_ops, ARRAY_SIZE(ip_vs_ops));
>  	ipvs->enable = 0;	/* Disable packet reception */
>  	smp_wmb();
>  	ip_vs_sync_net_cleanup(ipvs);
> -- 
> 2.20.1

Regards

--
Julian Anastasov <ja@ssi.bg>

Re: [PATCH v2] ipvs: Fix use-after-free in ip_vs_in

[Simon Horman]

On Sun, May 19, 2019 at 01:09:24PM +0300, Julian Anastasov wrote:
> 
> 	Hello,
> 
> On Fri, 17 May 2019, YueHaibing wrote:
> 
> > BUG: KASAN: use-after-free in ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
> > Read of size 4 at addr ffff8881e9b26e2c by task sshd/5603
> > 
> > CPU: 0 PID: 5603 Comm: sshd Not tainted 4.19.39+ #30
> > Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
> > Call Trace:
> >  dump_stack+0x71/0xab
> >  print_address_description+0x6a/0x270
> >  kasan_report+0x179/0x2c0
> >  ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
> >  ip_vs_in+0xd8/0x170 [ip_vs]
> >  nf_hook_slow+0x5f/0xe0
> >  __ip_local_out+0x1d5/0x250
> >  ip_local_out+0x19/0x60
> >  __tcp_transmit_skb+0xba1/0x14f0
> >  tcp_write_xmit+0x41f/0x1ed0
> >  ? _copy_from_iter_full+0xca/0x340
> >  __tcp_push_pending_frames+0x52/0x140
> >  tcp_sendmsg_locked+0x787/0x1600
> >  ? tcp_sendpage+0x60/0x60
> >  ? inet_sk_set_state+0xb0/0xb0
> >  tcp_sendmsg+0x27/0x40
> >  sock_sendmsg+0x6d/0x80
> >  sock_write_iter+0x121/0x1c0
> >  ? sock_sendmsg+0x80/0x80
> >  __vfs_write+0x23e/0x370
> >  vfs_write+0xe7/0x230
> >  ksys_write+0xa1/0x120
> >  ? __ia32_sys_read+0x50/0x50
> >  ? __audit_syscall_exit+0x3ce/0x450
> >  do_syscall_64+0x73/0x200
> >  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > RIP: 0033:0x7ff6f6147c60
> > Code: 73 01 c3 48 8b 0d 28 12 2d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 5d 73 2d 00 00 75 10 b8 01 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83
> > RSP: 002b:00007ffd772ead18 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> > RAX: ffffffffffffffda RBX: 0000000000000034 RCX: 00007ff6f6147c60
> > RDX: 0000000000000034 RSI: 000055df30a31270 RDI: 0000000000000003
> > RBP: 000055df30a31270 R08: 0000000000000000 R09: 0000000000000000
> > R10: 00007ffd772ead70 R11: 0000000000000246 R12: 00007ffd772ead74
> > R13: 00007ffd772eae20 R14: 00007ffd772eae24 R15: 000055df2f12ddc0
> > 
> > Allocated by task 6052:
> >  kasan_kmalloc+0xa0/0xd0
> >  __kmalloc+0x10a/0x220
> >  ops_init+0x97/0x190
> >  register_pernet_operations+0x1ac/0x360
> >  register_pernet_subsys+0x24/0x40
> >  0xffffffffc0ea016d
> >  do_one_initcall+0x8b/0x253
> >  do_init_module+0xe3/0x335
> >  load_module+0x2fc0/0x3890
> >  __do_sys_finit_module+0x192/0x1c0
> >  do_syscall_64+0x73/0x200
> >  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > 
> > Freed by task 6067:
> >  __kasan_slab_free+0x130/0x180
> >  kfree+0x90/0x1a0
> >  ops_free_list.part.7+0xa6/0xc0
> >  unregister_pernet_operations+0x18b/0x1f0
> >  unregister_pernet_subsys+0x1d/0x30
> >  ip_vs_cleanup+0x1d/0xd2f [ip_vs]
> >  __x64_sys_delete_module+0x20c/0x300
> >  do_syscall_64+0x73/0x200
> >  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > 
> > The buggy address belongs to the object at ffff8881e9b26600 which belongs to the cache kmalloc-4096 of size 4096
> > The buggy address is located 2092 bytes inside of 4096-byte region [ffff8881e9b26600, ffff8881e9b27600)
> > The buggy address belongs to the page:
> > page:ffffea0007a6c800 count:1 mapcount:0 mapping:ffff888107c0e600 index:0x0 compound_mapcount: 0
> > flags: 0x17ffffc0008100(slab|head)
> > raw: 0017ffffc0008100 dead000000000100 dead000000000200 ffff888107c0e600
> > raw: 0000000000000000 0000000080070007 00000001ffffffff 0000000000000000
> > page dumped because: kasan: bad access detected
> > 
> > while unregistering ipvs module, ops_free_list calls
> > __ip_vs_cleanup, then nf_unregister_net_hooks be called to
> > do remove nf hook entries. It need a RCU period to finish,
> > however net->ipvs is set to NULL immediately, which will
> > trigger NULL pointer dereference when a packet is hooked
> > and handled by ip_vs_in where net->ipvs is dereferenced.
> > 
> > Another scene is ops_free_list call ops_free to free the
> > net_generic directly while __ip_vs_cleanup finished, then
> > calling ip_vs_in will triggers use-after-free.
> > 
> > This patch moves nf_unregister_net_hooks from __ip_vs_cleanup()
> > to __ip_vs_dev_cleanup(),  where rcu_barrier() is called by
> > unregister_pernet_device -> unregister_pernet_operations,
> > that will do the needed grace period.
> > 
> > Reported-by: Hulk Robot <hulkci@huawei.com>
> > Fixes: efe41606184e ("ipvs: convert to use pernet nf_hook api")
> > Suggested-by: Julian Anastasov <ja@ssi.bg>
> > Signed-off-by: YueHaibing <yuehaibing@huawei.com>
> 
> 	Looks good to me, thanks!
> 
> Acked-by: Julian Anastasov <ja@ssi.bg>
> 
> 	It should restore the order of unregistrations before
> the mentioned commit and to ensure grace period before stopping
> the traffic and unregistering ipvs_core_ops where traffic is not
> expected.

Signed-off-by: Simon Horman <horms@verge.net.au>

Pablo, could you consider applying this to nf?

> 
> > ---
> > v2: fix by moving nf_unregister_net_hooks from __ip_vs_cleanup() to __ip_vs_dev_cleanup()
> > ---
> >  net/netfilter/ipvs/ip_vs_core.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> > index 14457551bcb4..8ebf21149ec3 100644
> > --- a/net/netfilter/ipvs/ip_vs_core.c
> > +++ b/net/netfilter/ipvs/ip_vs_core.c
> > @@ -2312,7 +2312,6 @@ static void __net_exit __ip_vs_cleanup(struct net *net)
> >  {
> >  	struct netns_ipvs *ipvs = net_ipvs(net);
> >  
> > -	nf_unregister_net_hooks(net, ip_vs_ops, ARRAY_SIZE(ip_vs_ops));
> >  	ip_vs_service_net_cleanup(ipvs);	/* ip_vs_flush() with locks */
> >  	ip_vs_conn_net_cleanup(ipvs);
> >  	ip_vs_app_net_cleanup(ipvs);
> > @@ -2327,6 +2326,7 @@ static void __net_exit __ip_vs_dev_cleanup(struct net *net)
> >  {
> >  	struct netns_ipvs *ipvs = net_ipvs(net);
> >  	EnterFunction(2);
> > +	nf_unregister_net_hooks(net, ip_vs_ops, ARRAY_SIZE(ip_vs_ops));
> >  	ipvs->enable = 0;	/* Disable packet reception */
> >  	smp_wmb();
> >  	ip_vs_sync_net_cleanup(ipvs);
> > -- 
> > 2.20.1
> 
> Regards
> 
> --
> Julian Anastasov <ja@ssi.bg>
> 

Re: [PATCH v2] ipvs: Fix use-after-free in ip_vs_in

[Pablo Neira Ayuso]

On Fri, May 17, 2019 at 10:31:49PM +0800, YueHaibing wrote:
> BUG: KASAN: use-after-free in ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
> Read of size 4 at addr ffff8881e9b26e2c by task sshd/5603

Applied, thanks.