From 6d1a3e042f55861a785527a35a6f1ab4217ee810 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 11 Jul 2011 02:49:52 +0000 Subject: [PATCH] inetpeer: kill inet_putpeer race We currently can free inetpeer entries too early : [ 782.636674] WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (f130f44c) [ 782.636677] 1f7b13c100000000000000000000000002000000000000000000000000000000 [ 782.636686] i i i i u u u u i i i i u u u u i i i i u u u u u u u u u u u u [ 782.636694] ^ [ 782.636696] [ 782.636698] Pid: 4638, comm: ssh Not tainted 3.0.0-rc5+ #270 Hewlett-Packard HP Compaq 6005 Pro SFF PC/3047h [ 782.636702] EIP: 0060:[] EFLAGS: 00010286 CPU: 0 [ 782.636707] EIP is at inet_getpeer+0x25b/0x5a0 [ 782.636709] EAX: 00000002 EBX: 00010080 ECX: f130f3c0 EDX: f0209d30 [ 782.636711] ESI: 0000bc87 EDI: 0000ea60 EBP: f0209ddc ESP: c173134c [ 782.636712] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 [ 782.636714] CR0: 8005003b CR2: f0beca80 CR3: 30246000 CR4: 000006d0 [ 782.636716] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 [ 782.636717] DR6: ffff4ff0 DR7: 00000400 [ 782.636718] [] rt_set_nexthop.clone.45+0x56/0x220 [ 782.636722] [] __ip_route_output_key+0x309/0x860 [ 782.636724] [] tcp_v4_connect+0x124/0x450 [ 782.636728] [] inet_stream_connect+0xa3/0x270 [ 782.636731] [] sys_connect+0xa1/0xb0 [ 782.636733] [] sys_socketcall+0x25d/0x2a0 [ 782.636736] [] sysenter_do_call+0x12/0x28 [ 782.636738] [] 0xffffffff Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/inetpeer.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c index dafbf2c98b28..90c5f0d1bcf3 100644 --- a/net/ipv4/inetpeer.c +++ b/net/ipv4/inetpeer.c @@ -373,11 +373,14 @@ static int inet_peer_gc(struct inet_peer_base *base, while (stackptr > stack) { stackptr--; p = rcu_deref_locked(**stackptr, base); - delta = (__u32)jiffies - p->dtime; - if (atomic_read(&p->refcnt) == 0 && delta >= ttl && - atomic_cmpxchg(&p->refcnt, 0, -1) == 0) { - p->gc_next = gchead; - gchead = p; + if (atomic_read(&p->refcnt) == 0) { + smp_rmb(); + delta = (__u32)jiffies - p->dtime; + if (delta >= ttl && + atomic_cmpxchg(&p->refcnt, 0, -1) == 0) { + p->gc_next = gchead; + gchead = p; + } } } while ((p = gchead) != NULL) { @@ -456,6 +459,7 @@ EXPORT_SYMBOL_GPL(inet_getpeer); void inet_putpeer(struct inet_peer *p) { p->dtime = (__u32)jiffies; + smp_mb__before_atomic_dec(); atomic_dec(&p->refcnt); } EXPORT_SYMBOL_GPL(inet_putpeer); -- 2.20.1