@@ -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);
This is a note to let you know that I have just added a patch titled ipv4: fix a race in ip4_datagram_release_cb() to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11.6. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From d32874a94010fbf164411f8bb4ec88d39e7f4939 Mon Sep 17 00:00:00 2001 From: Eric Dumazet <edumazet@google.com> Date: Tue, 10 Jun 2014 06:43:01 -0700 Subject: ipv4: fix a race in ip4_datagram_release_cb() [ Upstream commit 9709674e68646cee5a24e3000b3558d25412203a ] 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> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- net/ipv4/datagram.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) -- 1.9.1