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Message-ID: <1386727643.30495.363.camel@edumazet-glaptop2.roam.corp.google.com>
Date: Tue, 10 Dec 2013 18:07:23 -0800
From: Eric Dumazet <eric.dumazet@...il.com>
To: Dave Jones <davej@...hat.com>,
Shawn Bohrer <sbohrer@...advisors.com>,
David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Subject: [PATCH] udp: ipv4: fix an use after free in __udp4_lib_rcv()
From: Eric Dumazet <edumazet@...gle.com>
Dave Jones reported a use after free in UDP stack :
[ 5059.434216] =========================
[ 5059.434314] [ BUG: held lock freed! ]
[ 5059.434420] 3.13.0-rc3+ #9 Not tainted
[ 5059.434520] -------------------------
[ 5059.434620] named/863 is freeing memory ffff88005e960000-ffff88005e96061f, with a lock still held there!
[ 5059.434815] (slock-AF_INET){+.-...}, at: [<ffffffff8149bd21>] udp_queue_rcv_skb+0xd1/0x4b0
[ 5059.435012] 3 locks held by named/863:
[ 5059.435086] #0: (rcu_read_lock){.+.+..}, at: [<ffffffff8143054d>] __netif_receive_skb_core+0x11d/0x940
[ 5059.435295] #1: (rcu_read_lock){.+.+..}, at: [<ffffffff81467a5e>] ip_local_deliver_finish+0x3e/0x410
[ 5059.435500] #2: (slock-AF_INET){+.-...}, at: [<ffffffff8149bd21>] udp_queue_rcv_skb+0xd1/0x4b0
[ 5059.435734]
stack backtrace:
[ 5059.435858] CPU: 0 PID: 863 Comm: named Not tainted 3.13.0-rc3+ #9 [loadavg: 0.21 0.06 0.06 1/115 1365]
[ 5059.436052] Hardware name: /D510MO, BIOS MOPNV10J.86A.0175.2010.0308.0620 03/08/2010
[ 5059.436223] 0000000000000002 ffff88007e203ad8 ffffffff8153a372 ffff8800677130e0
[ 5059.436390] ffff88007e203b10 ffffffff8108cafa ffff88005e960000 ffff88007b00cfc0
[ 5059.436554] ffffea00017a5800 ffffffff8141c490 0000000000000246 ffff88007e203b48
[ 5059.436718] Call Trace:
[ 5059.436769] <IRQ> [<ffffffff8153a372>] dump_stack+0x4d/0x66
[ 5059.436904] [<ffffffff8108cafa>] debug_check_no_locks_freed+0x15a/0x160
[ 5059.437037] [<ffffffff8141c490>] ? __sk_free+0x110/0x230
[ 5059.437147] [<ffffffff8112da2a>] kmem_cache_free+0x6a/0x150
[ 5059.437260] [<ffffffff8141c490>] __sk_free+0x110/0x230
[ 5059.437364] [<ffffffff8141c5c9>] sk_free+0x19/0x20
[ 5059.437463] [<ffffffff8141cb25>] sock_edemux+0x25/0x40
[ 5059.437567] [<ffffffff8141c181>] sock_queue_rcv_skb+0x81/0x280
[ 5059.437685] [<ffffffff8149bd21>] ? udp_queue_rcv_skb+0xd1/0x4b0
[ 5059.437805] [<ffffffff81499c82>] __udp_queue_rcv_skb+0x42/0x240
[ 5059.437925] [<ffffffff81541d25>] ? _raw_spin_lock+0x65/0x70
[ 5059.438038] [<ffffffff8149bebb>] udp_queue_rcv_skb+0x26b/0x4b0
[ 5059.438155] [<ffffffff8149c712>] __udp4_lib_rcv+0x152/0xb00
[ 5059.438269] [<ffffffff8149d7f5>] udp_rcv+0x15/0x20
[ 5059.438367] [<ffffffff81467b2f>] ip_local_deliver_finish+0x10f/0x410
[ 5059.438492] [<ffffffff81467a5e>] ? ip_local_deliver_finish+0x3e/0x410
[ 5059.438621] [<ffffffff81468653>] ip_local_deliver+0x43/0x80
[ 5059.438733] [<ffffffff81467f70>] ip_rcv_finish+0x140/0x5a0
[ 5059.438843] [<ffffffff81468926>] ip_rcv+0x296/0x3f0
[ 5059.438945] [<ffffffff81430b72>] __netif_receive_skb_core+0x742/0x940
[ 5059.439074] [<ffffffff8143054d>] ? __netif_receive_skb_core+0x11d/0x940
[ 5059.442231] [<ffffffff8108c81d>] ? trace_hardirqs_on+0xd/0x10
[ 5059.442231] [<ffffffff81430d83>] __netif_receive_skb+0x13/0x60
[ 5059.442231] [<ffffffff81431c1e>] netif_receive_skb+0x1e/0x1f0
[ 5059.442231] [<ffffffff814334e0>] napi_gro_receive+0x70/0xa0
[ 5059.442231] [<ffffffffa01de426>] rtl8169_poll+0x166/0x700 [r8169]
[ 5059.442231] [<ffffffff81432bc9>] net_rx_action+0x129/0x1e0
[ 5059.442231] [<ffffffff810478cd>] __do_softirq+0xed/0x240
[ 5059.442231] [<ffffffff81047e25>] irq_exit+0x125/0x140
[ 5059.442231] [<ffffffff81004241>] do_IRQ+0x51/0xc0
[ 5059.442231] [<ffffffff81542bef>] common_interrupt+0x6f/0x6f
We need to keep a reference on the socket, by using skb_steal_sock()
at the right place.
Note that another patch is needed to fix a race in
udp_sk_rx_dst_set(), as we hold no lock protecting the dst.
Fixes: 421b3885bf6d ("udp: ipv4: Add udp early demux")
Reported-by: Dave Jones <davej@...hat.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Shawn Bohrer <sbohrer@...advisors.com>
---
net/ipv4/udp.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 44f6a20..2e2aecb 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -560,15 +560,11 @@ static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
__be16 sport, __be16 dport,
struct udp_table *udptable)
{
- struct sock *sk;
const struct iphdr *iph = ip_hdr(skb);
- if (unlikely(sk = skb_steal_sock(skb)))
- return sk;
- else
- return __udp4_lib_lookup(dev_net(skb_dst(skb)->dev), iph->saddr, sport,
- iph->daddr, dport, inet_iif(skb),
- udptable);
+ return __udp4_lib_lookup(dev_net(skb_dst(skb)->dev), iph->saddr, sport,
+ iph->daddr, dport, inet_iif(skb),
+ udptable);
}
struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
@@ -1739,15 +1735,15 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
if (udp4_csum_init(skb, uh, proto))
goto csum_error;
- if (skb->sk) {
+ sk = skb_steal_sock(skb);
+ if (sk) {
int ret;
- sk = skb->sk;
if (unlikely(sk->sk_rx_dst == NULL))
udp_sk_rx_dst_set(sk, skb);
ret = udp_queue_rcv_skb(sk, skb);
-
+ sock_put(sk);
/* a return value > 0 means to resubmit the input, but
* it wants the return to be -protocol, or 0
*/
--
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