From: Eric Dumazet Date: Tue, 18 Jun 2019 18:09:00 +0000 (-0700) Subject: inet: fix various use-after-free in defrags units X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=d5dd88794a13c2f24cce31abad7a0a6c5e0ed2db;p=openwrt%2Fstaging%2Fblogic.git inet: fix various use-after-free in defrags units syzbot reported another issue caused by my recent patches. [1] The issue here is that fqdir_exit() is initiating a work queue and immediately returns. A bit later cleanup_net() was able to free the MIB (percpu data) and the whole struct net was freed, but we had active frag timers that fired and triggered use-after-free. We need to make sure that timers can catch fqdir->dead being set, to bailout. Since RCU is used for the reader side, this means we want to respect an RCU grace period between these operations : 1) qfdir->dead = 1; 2) netns dismantle (freeing of various data structure) This patch uses new new (struct pernet_operations)->pre_exit infrastructure to ensures a full RCU grace period happens between fqdir_pre_exit() and fqdir_exit() This also means we can use a regular work queue, we no longer need rcu_work. Tested: $ time for i in {1..1000}; do unshare -n /bin/false;done real 0m2.585s user 0m0.160s sys 0m2.214s [1] BUG: KASAN: use-after-free in ip_expire+0x73e/0x800 net/ipv4/ip_fragment.c:152 Read of size 8 at addr ffff88808b9fe330 by task syz-executor.4/11860 CPU: 1 PID: 11860 Comm: syz-executor.4 Not tainted 5.2.0-rc2+ #22 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+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 kasan_report+0x12/0x20 mm/kasan/common.c:614 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132 ip_expire+0x73e/0x800 net/ipv4/ip_fragment.c:152 call_timer_fn+0x193/0x720 kernel/time/timer.c:1322 expire_timers kernel/time/timer.c:1366 [inline] __run_timers kernel/time/timer.c:1685 [inline] __run_timers kernel/time/timer.c:1653 [inline] run_timer_softirq+0x66f/0x1740 kernel/time/timer.c:1698 __do_softirq+0x25c/0x94c kernel/softirq.c:293 invoke_softirq kernel/softirq.c:374 [inline] irq_exit+0x180/0x1d0 kernel/softirq.c:414 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x13b/0x550 arch/x86/kernel/apic/apic.c:1068 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:806 RIP: 0010:tomoyo_domain_quota_is_ok+0x131/0x540 security/tomoyo/util.c:1035 Code: 24 4c 3b 65 d0 0f 84 9c 00 00 00 e8 19 1d 73 fe 49 8d 7c 24 18 48 ba 00 00 00 00 00 fc ff df 48 89 f8 48 c1 e8 03 0f b6 04 10 <48> 89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 69 03 00 00 41 0f b6 5c RSP: 0018:ffff88806ae079c0 EFLAGS: 00000a02 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000000 RBX: 0000000000000010 RCX: ffffc9000e655000 RDX: dffffc0000000000 RSI: ffffffff82fd88a7 RDI: ffff888086202398 RBP: ffff88806ae07a00 R08: ffff88808b6c8700 R09: ffffed100d5c0f4d R10: ffffed100d5c0f4c R11: 0000000000000000 R12: ffff888086202380 R13: 0000000000000030 R14: 00000000000000d3 R15: 0000000000000000 tomoyo_supervisor+0x2e8/0xef0 security/tomoyo/common.c:2087 tomoyo_audit_path_number_log security/tomoyo/file.c:235 [inline] tomoyo_path_number_perm+0x42f/0x520 security/tomoyo/file.c:734 tomoyo_file_ioctl+0x23/0x30 security/tomoyo/tomoyo.c:335 security_file_ioctl+0x77/0xc0 security/security.c:1370 ksys_ioctl+0x57/0xd0 fs/ioctl.c:711 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4592c9 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f8db5e44c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004592c9 RDX: 0000000020000080 RSI: 00000000000089f1 RDI: 0000000000000006 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f8db5e456d4 R13: 00000000004cc770 R14: 00000000004d5cd8 R15: 00000000ffffffff Allocated by task 9047: save_stack+0x23/0x90 mm/kasan/common.c:71 set_track mm/kasan/common.c:79 [inline] __kasan_kmalloc mm/kasan/common.c:489 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:497 slab_post_alloc_hook mm/slab.h:437 [inline] slab_alloc mm/slab.c:3326 [inline] kmem_cache_alloc+0x11a/0x6f0 mm/slab.c:3488 kmem_cache_zalloc include/linux/slab.h:732 [inline] net_alloc net/core/net_namespace.c:386 [inline] copy_net_ns+0xed/0x340 net/core/net_namespace.c:426 create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:107 unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:206 ksys_unshare+0x440/0x980 kernel/fork.c:2692 __do_sys_unshare kernel/fork.c:2760 [inline] __se_sys_unshare kernel/fork.c:2758 [inline] __x64_sys_unshare+0x31/0x40 kernel/fork.c:2758 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 2541: save_stack+0x23/0x90 mm/kasan/common.c:71 set_track mm/kasan/common.c:79 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459 __cache_free mm/slab.c:3432 [inline] kmem_cache_free+0x86/0x260 mm/slab.c:3698 net_free net/core/net_namespace.c:402 [inline] net_drop_ns.part.0+0x70/0x90 net/core/net_namespace.c:409 net_drop_ns net/core/net_namespace.c:408 [inline] cleanup_net+0x538/0x960 net/core/net_namespace.c:571 process_one_work+0x989/0x1790 kernel/workqueue.c:2269 worker_thread+0x98/0xe40 kernel/workqueue.c:2415 kthread+0x354/0x420 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 The buggy address belongs to the object at ffff88808b9fe100 which belongs to the cache net_namespace of size 6784 The buggy address is located 560 bytes inside of 6784-byte region [ffff88808b9fe100, ffff88808b9ffb80) The buggy address belongs to the page: page:ffffea00022e7f80 refcount:1 mapcount:0 mapping:ffff88821b6f60c0 index:0x0 compound_mapcount: 0 flags: 0x1fffc0000010200(slab|head) raw: 01fffc0000010200 ffffea000256f288 ffffea0001bbef08 ffff88821b6f60c0 raw: 0000000000000000 ffff88808b9fe100 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88808b9fe200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808b9fe280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88808b9fe300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88808b9fe380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808b9fe400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb Fixes: 3c8fc8782044 ("inet: frags: rework rhashtable dismantle") Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: David S. Miller --- diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h index e91b79ad4e4a..46574d996f1d 100644 --- a/include/net/inet_frag.h +++ b/include/net/inet_frag.h @@ -20,7 +20,7 @@ struct fqdir { /* Keep atomic mem on separate cachelines in structs that include it */ atomic_long_t mem ____cacheline_aligned_in_smp; - struct rcu_work destroy_rwork; + struct work_struct destroy_work; }; /** @@ -113,6 +113,12 @@ int inet_frags_init(struct inet_frags *); void inet_frags_fini(struct inet_frags *); int fqdir_init(struct fqdir **fqdirp, struct inet_frags *f, struct net *net); + +static void inline fqdir_pre_exit(struct fqdir *fqdir) +{ + fqdir->high_thresh = 0; /* prevent creation of new frags */ + fqdir->dead = true; +} void fqdir_exit(struct fqdir *fqdir); void inet_frag_kill(struct inet_frag_queue *q); diff --git a/include/net/ipv6_frag.h b/include/net/ipv6_frag.h index 1f77fb4dc79d..a21e8b1381a1 100644 --- a/include/net/ipv6_frag.h +++ b/include/net/ipv6_frag.h @@ -67,6 +67,8 @@ ip6frag_expire_frag_queue(struct net *net, struct frag_queue *fq) struct sk_buff *head; rcu_read_lock(); + if (fq->q.fqdir->dead) + goto out_rcu_unlock; spin_lock(&fq->q.lock); if (fq->q.flags & INET_FRAG_COMPLETE) diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c index a0ed13cd120e..e4aba5d485be 100644 --- a/net/ieee802154/6lowpan/reassembly.c +++ b/net/ieee802154/6lowpan/reassembly.c @@ -459,6 +459,14 @@ static int __net_init lowpan_frags_init_net(struct net *net) return res; } +static void __net_exit lowpan_frags_pre_exit_net(struct net *net) +{ + struct netns_ieee802154_lowpan *ieee802154_lowpan = + net_ieee802154_lowpan(net); + + fqdir_pre_exit(ieee802154_lowpan->fqdir); +} + static void __net_exit lowpan_frags_exit_net(struct net *net) { struct netns_ieee802154_lowpan *ieee802154_lowpan = @@ -469,8 +477,9 @@ static void __net_exit lowpan_frags_exit_net(struct net *net) } static struct pernet_operations lowpan_frags_ops = { - .init = lowpan_frags_init_net, - .exit = lowpan_frags_exit_net, + .init = lowpan_frags_init_net, + .pre_exit = lowpan_frags_pre_exit_net, + .exit = lowpan_frags_exit_net, }; static u32 lowpan_key_hashfn(const void *data, u32 len, u32 seed) diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c index 5c25727d491e..d666756be5f1 100644 --- a/net/ipv4/inet_fragment.c +++ b/net/ipv4/inet_fragment.c @@ -145,10 +145,9 @@ static void inet_frags_free_cb(void *ptr, void *arg) inet_frag_destroy(fq); } -static void fqdir_rwork_fn(struct work_struct *work) +static void fqdir_work_fn(struct work_struct *work) { - struct fqdir *fqdir = container_of(to_rcu_work(work), - struct fqdir, destroy_rwork); + struct fqdir *fqdir = container_of(work, struct fqdir, destroy_work); struct inet_frags *f = fqdir->f; rhashtable_free_and_destroy(&fqdir->rhashtable, inet_frags_free_cb, NULL); @@ -187,18 +186,8 @@ EXPORT_SYMBOL(fqdir_init); void fqdir_exit(struct fqdir *fqdir) { - fqdir->high_thresh = 0; /* prevent creation of new frags */ - - fqdir->dead = true; - - /* call_rcu is supposed to provide memory barrier semantics, - * separating the setting of fqdir->dead with the destruction - * work. This implicit barrier is paired with inet_frag_kill(). - */ - - INIT_RCU_WORK(&fqdir->destroy_rwork, fqdir_rwork_fn); - queue_rcu_work(system_wq, &fqdir->destroy_rwork); - + INIT_WORK(&fqdir->destroy_work, fqdir_work_fn); + queue_work(system_wq, &fqdir->destroy_work); } EXPORT_SYMBOL(fqdir_exit); diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c index 1ffaec056821..4385eb9e781f 100644 --- a/net/ipv4/ip_fragment.c +++ b/net/ipv4/ip_fragment.c @@ -143,6 +143,10 @@ static void ip_expire(struct timer_list *t) net = qp->q.fqdir->net; rcu_read_lock(); + + if (qp->q.fqdir->dead) + goto out_rcu_unlock; + spin_lock(&qp->q.lock); if (qp->q.flags & INET_FRAG_COMPLETE) @@ -676,6 +680,11 @@ static int __net_init ipv4_frags_init_net(struct net *net) return res; } +static void __net_exit ipv4_frags_pre_exit_net(struct net *net) +{ + fqdir_pre_exit(net->ipv4.fqdir); +} + static void __net_exit ipv4_frags_exit_net(struct net *net) { ip4_frags_ns_ctl_unregister(net); @@ -683,8 +692,9 @@ static void __net_exit ipv4_frags_exit_net(struct net *net) } static struct pernet_operations ip4_frags_ops = { - .init = ipv4_frags_init_net, - .exit = ipv4_frags_exit_net, + .init = ipv4_frags_init_net, + .pre_exit = ipv4_frags_pre_exit_net, + .exit = ipv4_frags_exit_net, }; diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c index b8962d4d6ae6..3299a389d166 100644 --- a/net/ipv6/netfilter/nf_conntrack_reasm.c +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c @@ -499,6 +499,11 @@ static int nf_ct_net_init(struct net *net) return res; } +static void nf_ct_net_pre_exit(struct net *net) +{ + fqdir_pre_exit(net->nf_frag.fqdir); +} + static void nf_ct_net_exit(struct net *net) { nf_ct_frags6_sysctl_unregister(net); @@ -506,8 +511,9 @@ static void nf_ct_net_exit(struct net *net) } static struct pernet_operations nf_ct_net_ops = { - .init = nf_ct_net_init, - .exit = nf_ct_net_exit, + .init = nf_ct_net_init, + .pre_exit = nf_ct_net_pre_exit, + .exit = nf_ct_net_exit, }; static const struct rhashtable_params nfct_rhash_params = { diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c index 0c9fd8a7c4e7..ca05b16f1bb9 100644 --- a/net/ipv6/reassembly.c +++ b/net/ipv6/reassembly.c @@ -520,6 +520,11 @@ static int __net_init ipv6_frags_init_net(struct net *net) return res; } +static void __net_exit ipv6_frags_pre_exit_net(struct net *net) +{ + fqdir_pre_exit(net->ipv6.fqdir); +} + static void __net_exit ipv6_frags_exit_net(struct net *net) { ip6_frags_ns_sysctl_unregister(net); @@ -527,8 +532,9 @@ static void __net_exit ipv6_frags_exit_net(struct net *net) } static struct pernet_operations ip6_frags_ops = { - .init = ipv6_frags_init_net, - .exit = ipv6_frags_exit_net, + .init = ipv6_frags_init_net, + .pre_exit = ipv6_frags_pre_exit_net, + .exit = ipv6_frags_exit_net, }; static const struct rhashtable_params ip6_rhash_params = {