From 0de29ed1fe9a1f419f2b58893e292f0147559cda Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Wed, 22 Feb 2017 12:35:27 +0300 Subject: [PATCH 1/1] net/dccp: fix use after free in tw_timer_handler() commit ec7cb62d18d854ea09df8b7194e7e710985f8b9a upstream. DCCP doesn't purge timewait sockets on network namespace shutdown. So, after net namespace destroyed we could still have an active timer which will trigger use after free in tw_timer_handler(): BUG: KASAN: use-after-free in tw_timer_handler+0x4a/0xa0 at addr ffff88010e0d1e10 Read of size 8 by task swapper/1/0 Call Trace: __asan_load8+0x54/0x90 tw_timer_handler+0x4a/0xa0 call_timer_fn+0x127/0x480 expire_timers+0x1db/0x2e0 run_timer_softirq+0x12f/0x2a0 __do_softirq+0x105/0x5b4 irq_exit+0xdd/0xf0 smp_apic_timer_interrupt+0x57/0x70 apic_timer_interrupt+0x90/0xa0 Object at ffff88010e0d1bc0, in cache net_namespace size: 6848 Allocated: save_stack_trace+0x1b/0x20 kasan_kmalloc+0xee/0x180 kasan_slab_alloc+0x12/0x20 kmem_cache_alloc+0x134/0x310 copy_net_ns+0x8d/0x280 create_new_namespaces+0x23f/0x340 unshare_nsproxy_namespaces+0x75/0xf0 SyS_unshare+0x299/0x4f0 entry_SYSCALL_64_fastpath+0x18/0xad Freed: save_stack_trace+0x1b/0x20 kasan_slab_free+0xae/0x180 kmem_cache_free+0xb4/0x350 net_drop_ns+0x3f/0x50 cleanup_net+0x3df/0x450 process_one_work+0x419/0xbb0 worker_thread+0x92/0x850 kthread+0x192/0x1e0 ret_from_fork+0x2e/0x40 Add .exit_batch hook to dccp_v4_ops()/dccp_v6_ops() which will purge timewait sockets on net namespace destruction and prevent above issue. Fixes: f2bf415cfed7 ("mib: add net to NET_ADD_STATS_BH") Reported-by: Dmitry Vyukov Signed-off-by: Andrey Ryabinin Acked-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller [bwh: Backported to 3.2: pass twdr parameter to inet_twsk_purge() Signed-off-by: Ben Hutchings --- net/dccp/ipv4.c | 6 ++++++ net/dccp/ipv6.c | 6 ++++++ 2 files changed, 12 insertions(+) diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c index 98607e19533e..4cdfa448f8e3 100644 --- a/net/dccp/ipv4.c +++ b/net/dccp/ipv4.c @@ -1032,9 +1032,15 @@ static void __net_exit dccp_v4_exit_net(struct net *net) inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); } +static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list) +{ + inet_twsk_purge(&dccp_hashinfo, &dccp_death_row, AF_INET); +} + static struct pernet_operations dccp_v4_ops = { .init = dccp_v4_init_net, .exit = dccp_v4_exit_net, + .exit_batch = dccp_v4_exit_batch, }; static int __init dccp_v4_init(void) diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c index e10d8512d431..61716f6f4945 100644 --- a/net/dccp/ipv6.c +++ b/net/dccp/ipv6.c @@ -1157,9 +1157,15 @@ static void __net_exit dccp_v6_exit_net(struct net *net) inet_ctl_sock_destroy(net->dccp.v6_ctl_sk); } +static void __net_exit dccp_v6_exit_batch(struct list_head *net_exit_list) +{ + inet_twsk_purge(&dccp_hashinfo, &dccp_death_row, AF_INET6); +} + static struct pernet_operations dccp_v6_ops = { .init = dccp_v6_init_net, .exit = dccp_v6_exit_net, + .exit_batch = dccp_v6_exit_batch, }; static int __init dccp_v6_init(void) -- 2.39.2