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authorEric Dumazet <edumazet@google.com>2014-06-10 06:43:01 -0700
committerDavid S. Miller <davem@davemloft.net>2014-06-11 15:39:18 -0700
commit9709674e68646cee5a24e3000b3558d25412203a (patch)
tree34667c6bb0a09f48d5398b3e17de376377721abd
parenta101ccd141fa777febc510a5c3f3da0c23cd47ce (diff)
ipv4: fix a race in ip4_datagram_release_cb()
Alexey gave a AddressSanitizer[1] report that finally gave a good hint at where was the origin of various problems already reported by Dormando in the past [2] Problem comes from the fact that UDP can have a lockless TX path, and concurrent threads can manipulate sk_dst_cache, while another thread, is holding socket lock and calls __sk_dst_set() in ip4_datagram_release_cb() (this was added in linux-3.8) It seems that all we need to do is to use sk_dst_check() and sk_dst_set() so that all the writers hold same spinlock (sk->sk_dst_lock) to prevent corruptions. TCP stack do not need this protection, as all sk_dst_cache writers hold the socket lock. [1] https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel AddressSanitizer: heap-use-after-free in ipv4_dst_check Read of size 2 by thread T15453: [<ffffffff817daa3a>] ipv4_dst_check+0x1a/0x90 ./net/ipv4/route.c:1116 [<ffffffff8175b789>] __sk_dst_check+0x89/0xe0 ./net/core/sock.c:531 [<ffffffff81830a36>] ip4_datagram_release_cb+0x46/0x390 ??:0 [<ffffffff8175eaea>] release_sock+0x17a/0x230 ./net/core/sock.c:2413 [<ffffffff81830882>] ip4_datagram_connect+0x462/0x5d0 ??:0 [<ffffffff81846d06>] inet_dgram_connect+0x76/0xd0 ./net/ipv4/af_inet.c:534 [<ffffffff817580ac>] SYSC_connect+0x15c/0x1c0 ./net/socket.c:1701 [<ffffffff817596ce>] SyS_connect+0xe/0x10 ./net/socket.c:1682 [<ffffffff818b0a29>] system_call_fastpath+0x16/0x1b ./arch/x86/kernel/entry_64.S:629 Freed by thread T15455: [<ffffffff8178d9b8>] dst_destroy+0xa8/0x160 ./net/core/dst.c:251 [<ffffffff8178de25>] dst_release+0x45/0x80 ./net/core/dst.c:280 [<ffffffff818304c1>] ip4_datagram_connect+0xa1/0x5d0 ??:0 [<ffffffff81846d06>] inet_dgram_connect+0x76/0xd0 ./net/ipv4/af_inet.c:534 [<ffffffff817580ac>] SYSC_connect+0x15c/0x1c0 ./net/socket.c:1701 [<ffffffff817596ce>] SyS_connect+0xe/0x10 ./net/socket.c:1682 [<ffffffff818b0a29>] system_call_fastpath+0x16/0x1b ./arch/x86/kernel/entry_64.S:629 Allocated by thread T15453: [<ffffffff8178d291>] dst_alloc+0x81/0x2b0 ./net/core/dst.c:171 [<ffffffff817db3b7>] rt_dst_alloc+0x47/0x50 ./net/ipv4/route.c:1406 [< inlined >] __ip_route_output_key+0x3e8/0xf70 __mkroute_output ./net/ipv4/route.c:1939 [<ffffffff817dde08>] __ip_route_output_key+0x3e8/0xf70 ./net/ipv4/route.c:2161 [<ffffffff817deb34>] ip_route_output_flow+0x14/0x30 ./net/ipv4/route.c:2249 [<ffffffff81830737>] ip4_datagram_connect+0x317/0x5d0 ??:0 [<ffffffff81846d06>] inet_dgram_connect+0x76/0xd0 ./net/ipv4/af_inet.c:534 [<ffffffff817580ac>] SYSC_connect+0x15c/0x1c0 ./net/socket.c:1701 [<ffffffff817596ce>] SyS_connect+0xe/0x10 ./net/socket.c:1682 [<ffffffff818b0a29>] system_call_fastpath+0x16/0x1b ./arch/x86/kernel/entry_64.S:629 [2] <4>[196727.311203] general protection fault: 0000 [#1] SMP <4>[196727.311224] Modules linked in: xt_TEE xt_dscp xt_DSCP macvlan bridge coretemp crc32_pclmul ghash_clmulni_intel gpio_ich microcode ipmi_watchdog ipmi_devintf sb_edac edac_core lpc_ich mfd_core tpm_tis tpm tpm_bios ipmi_si ipmi_msghandler isci igb libsas i2c_algo_bit ixgbe ptp pps_core mdio <4>[196727.311333] CPU: 17 PID: 0 Comm: swapper/17 Not tainted 3.10.26 #1 <4>[196727.311344] Hardware name: Supermicro X9DRi-LN4+/X9DR3-LN4+/X9DRi-LN4+/X9DR3-LN4+, BIOS 3.0 07/05/2013 <4>[196727.311364] task: ffff885e6f069700 ti: ffff885e6f072000 task.ti: ffff885e6f072000 <4>[196727.311377] RIP: 0010:[<ffffffff815f8c7f>] [<ffffffff815f8c7f>] ipv4_dst_destroy+0x4f/0x80 <4>[196727.311399] RSP: 0018:ffff885effd23a70 EFLAGS: 00010282 <4>[196727.311409] RAX: dead000000200200 RBX: ffff8854c398ecc0 RCX: 0000000000000040 <4>[196727.311423] RDX: dead000000100100 RSI: dead000000100100 RDI: dead000000200200 <4>[196727.311437] RBP: ffff885effd23a80 R08: ffffffff815fd9e0 R09: ffff885d5a590800 <4>[196727.311451] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 <4>[196727.311464] R13: ffffffff81c8c280 R14: 0000000000000000 R15: ffff880e85ee16ce <4>[196727.311510] FS: 0000000000000000(0000) GS:ffff885effd20000(0000) knlGS:0000000000000000 <4>[196727.311554] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 <4>[196727.311581] CR2: 00007a46751eb000 CR3: 0000005e65688000 CR4: 00000000000407e0 <4>[196727.311625] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 <4>[196727.311669] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 <4>[196727.311713] Stack: <4>[196727.311733] ffff8854c398ecc0 ffff8854c398ecc0 ffff885effd23ab0 ffffffff815b7f42 <4>[196727.311784] ffff88be6595bc00 ffff8854c398ecc0 0000000000000000 ffff8854c398ecc0 <4>[196727.311834] ffff885effd23ad0 ffffffff815b86c6 ffff885d5a590800 ffff8816827821c0 <4>[196727.311885] Call Trace: <4>[196727.311907] <IRQ> <4>[196727.311912] [<ffffffff815b7f42>] dst_destroy+0x32/0xe0 <4>[196727.311959] [<ffffffff815b86c6>] dst_release+0x56/0x80 <4>[196727.311986] [<ffffffff81620bd5>] tcp_v4_do_rcv+0x2a5/0x4a0 <4>[196727.312013] [<ffffffff81622b5a>] tcp_v4_rcv+0x7da/0x820 <4>[196727.312041] [<ffffffff815fd9e0>] ? ip_rcv_finish+0x360/0x360 <4>[196727.312070] [<ffffffff815de02d>] ? nf_hook_slow+0x7d/0x150 <4>[196727.312097] [<ffffffff815fd9e0>] ? ip_rcv_finish+0x360/0x360 <4>[196727.312125] [<ffffffff815fda92>] ip_local_deliver_finish+0xb2/0x230 <4>[196727.312154] [<ffffffff815fdd9a>] ip_local_deliver+0x4a/0x90 <4>[196727.312183] [<ffffffff815fd799>] ip_rcv_finish+0x119/0x360 <4>[196727.312212] [<ffffffff815fe00b>] ip_rcv+0x22b/0x340 <4>[196727.312242] [<ffffffffa0339680>] ? macvlan_broadcast+0x160/0x160 [macvlan] <4>[196727.312275] [<ffffffff815b0c62>] __netif_receive_skb_core+0x512/0x640 <4>[196727.312308] [<ffffffff811427fb>] ? kmem_cache_alloc+0x13b/0x150 <4>[196727.312338] [<ffffffff815b0db1>] __netif_receive_skb+0x21/0x70 <4>[196727.312368] [<ffffffff815b0fa1>] netif_receive_skb+0x31/0xa0 <4>[196727.312397] [<ffffffff815b1ae8>] napi_gro_receive+0xe8/0x140 <4>[196727.312433] [<ffffffffa00274f1>] ixgbe_poll+0x551/0x11f0 [ixgbe] <4>[196727.312463] [<ffffffff815fe00b>] ? ip_rcv+0x22b/0x340 <4>[196727.312491] [<ffffffff815b1691>] net_rx_action+0x111/0x210 <4>[196727.312521] [<ffffffff815b0db1>] ? __netif_receive_skb+0x21/0x70 <4>[196727.312552] [<ffffffff810519d0>] __do_softirq+0xd0/0x270 <4>[196727.312583] [<ffffffff816cef3c>] call_softirq+0x1c/0x30 <4>[196727.312613] [<ffffffff81004205>] do_softirq+0x55/0x90 <4>[196727.312640] [<ffffffff81051c85>] irq_exit+0x55/0x60 <4>[196727.312668] [<ffffffff816cf5c3>] do_IRQ+0x63/0xe0 <4>[196727.312696] [<ffffffff816c5aaa>] common_interrupt+0x6a/0x6a <4>[196727.312722] <EOI> <1>[196727.313071] RIP [<ffffffff815f8c7f>] ipv4_dst_destroy+0x4f/0x80 <4>[196727.313100] RSP <ffff885effd23a70> <4>[196727.313377] ---[ end trace 64b3f14fae0f2e29 ]--- <0>[196727.380908] Kernel panic - not syncing: Fatal exception in interrupt Reported-by: Alexey Preobrazhensky <preobr@google.com> Reported-by: dormando <dormando@rydia.ne> Signed-off-by: Eric Dumazet <edumazet@google.com> Fixes: 8141ed9fcedb2 ("ipv4: Add a socket release callback for datagram sockets") Cc: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/datagram.c20
1 files changed, 15 insertions, 5 deletions
diff --git a/net/ipv4/datagram.c b/net/ipv4/datagram.c
index 8b5134c..a3095fd 100644
--- a/net/ipv4/datagram.c
+++ b/net/ipv4/datagram.c
@@ -86,18 +86,26 @@ out:
}
EXPORT_SYMBOL(ip4_datagram_connect);
+/* Because UDP xmit path can manipulate sk_dst_cache without holding
+ * socket lock, we need to use sk_dst_set() here,
+ * even if we own the socket lock.
+ */
void ip4_datagram_release_cb(struct sock *sk)
{
const struct inet_sock *inet = inet_sk(sk);
const struct ip_options_rcu *inet_opt;
__be32 daddr = inet->inet_daddr;
+ struct dst_entry *dst;
struct flowi4 fl4;
struct rtable *rt;
- if (! __sk_dst_get(sk) || __sk_dst_check(sk, 0))
- return;
-
rcu_read_lock();
+
+ dst = __sk_dst_get(sk);
+ if (!dst || !dst->obsolete || dst->ops->check(dst, 0)) {
+ rcu_read_unlock();
+ return;
+ }
inet_opt = rcu_dereference(inet->inet_opt);
if (inet_opt && inet_opt->opt.srr)
daddr = inet_opt->opt.faddr;
@@ -105,8 +113,10 @@ void ip4_datagram_release_cb(struct sock *sk)
inet->inet_saddr, inet->inet_dport,
inet->inet_sport, sk->sk_protocol,
RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
- if (!IS_ERR(rt))
- __sk_dst_set(sk, &rt->dst);
+
+ dst = !IS_ERR(rt) ? &rt->dst : NULL;
+ sk_dst_set(sk, dst);
+
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(ip4_datagram_release_cb);