From: YueHaibing yuehaibing@huawei.com
[ Upstream commit 719c7d563c17b150877cee03a4b812a424989dfa ]
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 Acked-by: Julian Anastasov ja@ssi.bg Signed-off-by: Simon Horman horms@verge.net.au Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 a42c1bc7c698..62c0e80dcd71 100644 --- a/net/netfilter/ipvs/ip_vs_core.c +++ b/net/netfilter/ipvs/ip_vs_core.c @@ -2280,7 +2280,6 @@ 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); @@ -2295,6 +2294,7 @@ 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);