[PATCH 2.6.28] tcp_ipv6: fix use of uninitialized memory

[PATCH 2.6.28] tcp_ipv6: fix use of uninitialized memory

[Vegard Nossum]

>From 6544c4074aa5dde2e3f4d3e02f5601c1c33b770e Mon Sep 17 00:00:00 2001
From: Vegard Nossum <vegard.nossum@gmail.com>
Date: Tue, 9 Sep 2008 07:17:32 +0200
Subject: [PATCH] tcp_ipv6: fix use of uninitialized memory

inet6_rsk() is called on a struct request_sock * before we
have checked whether the socket is an ipv6 socket or a ipv6-
mapped ipv4 socket. The access that triggers this is the
inet_rsk(rsk)->inet6_rsk_offset dereference in inet6_rsk().

This is arguably not a critical error as the inet6_rsk_offset
is only used to compute a pointer which is never really used
(in the code path in question) anyway. But it might be a
latent error, so let's fix it.

Spotted by kmemcheck.

Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
---
 net/ipv6/tcp_ipv6.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 5b90b36..c9b6c13 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1286,7 +1286,7 @@ static struct sock * tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
 					  struct request_sock *req,
 					  struct dst_entry *dst)
 {
-	struct inet6_request_sock *treq = inet6_rsk(req);
+	struct inet6_request_sock *treq;
 	struct ipv6_pinfo *newnp, *np = inet6_sk(sk);
 	struct tcp6_sock *newtcp6sk;
 	struct inet_sock *newinet;
@@ -1350,6 +1350,7 @@ static struct sock * tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
 		return newsk;
 	}
 
+	treq = inet6_rsk(req);
 	opt = np->opt;
 
 	if (sk_acceptq_is_full(sk))
-- 
1.5.5.1

Re: [PATCH 2.6.28] tcp_ipv6: fix use of uninitialized memory

[Arnaldo Carvalho de Melo]

Em Fri, Sep 12, 2008 at 09:05:25AM +0200, Vegard Nossum escreveu:
> >From 6544c4074aa5dde2e3f4d3e02f5601c1c33b770e Mon Sep 17 00:00:00 2001
> From: Vegard Nossum <vegard.nossum@gmail.com>
> Date: Tue, 9 Sep 2008 07:17:32 +0200
> Subject: [PATCH] tcp_ipv6: fix use of uninitialized memory
> 
> inet6_rsk() is called on a struct request_sock * before we
> have checked whether the socket is an ipv6 socket or a ipv6-
> mapped ipv4 socket. The access that triggers this is the
> inet_rsk(rsk)->inet6_rsk_offset dereference in inet6_rsk().
> 
> This is arguably not a critical error as the inet6_rsk_offset
> is only used to compute a pointer which is never really used
> (in the code path in question) anyway. But it might be a
> latent error, so let's fix it.
> 
> Spotted by kmemcheck.

Humm, so this was poisoned at allocation and then when inet6_rsk_offset
was accessed it noticed, interesting, thanks!

Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
 
- Arnaldo

Re: [PATCH 2.6.28] tcp_ipv6: fix use of uninitialized memory

[David Miller]

From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Fri, 12 Sep 2008 09:44:05 -0300

> Em Fri, Sep 12, 2008 at 09:05:25AM +0200, Vegard Nossum escreveu:
> > >From 6544c4074aa5dde2e3f4d3e02f5601c1c33b770e Mon Sep 17 00:00:00 2001
> > From: Vegard Nossum <vegard.nossum@gmail.com>
> > Date: Tue, 9 Sep 2008 07:17:32 +0200
> > Subject: [PATCH] tcp_ipv6: fix use of uninitialized memory
> > 
> > inet6_rsk() is called on a struct request_sock * before we
> > have checked whether the socket is an ipv6 socket or a ipv6-
> > mapped ipv4 socket. The access that triggers this is the
> > inet_rsk(rsk)->inet6_rsk_offset dereference in inet6_rsk().
> > 
> > This is arguably not a critical error as the inet6_rsk_offset
> > is only used to compute a pointer which is never really used
> > (in the code path in question) anyway. But it might be a
> > latent error, so let's fix it.
> > 
> > Spotted by kmemcheck.
> 
> Humm, so this was poisoned at allocation and then when inet6_rsk_offset
> was accessed it noticed, interesting, thanks!
> 
> Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Good find :)  I'll add this to net-next-2.6, thanks!

Re: [PATCH 2.6.28] tcp_ipv6: fix use of uninitialized memory

[Ingo Molnar]

* David Miller <davem@davemloft.net> wrote:

> From: Arnaldo Carvalho de Melo <acme@redhat.com>
> Date: Fri, 12 Sep 2008 09:44:05 -0300
> 
> > Em Fri, Sep 12, 2008 at 09:05:25AM +0200, Vegard Nossum escreveu:
> > > >From 6544c4074aa5dde2e3f4d3e02f5601c1c33b770e Mon Sep 17 00:00:00 2001
> > > From: Vegard Nossum <vegard.nossum@gmail.com>
> > > Date: Tue, 9 Sep 2008 07:17:32 +0200
> > > Subject: [PATCH] tcp_ipv6: fix use of uninitialized memory
> > > 
> > > inet6_rsk() is called on a struct request_sock * before we
> > > have checked whether the socket is an ipv6 socket or a ipv6-
> > > mapped ipv4 socket. The access that triggers this is the
> > > inet_rsk(rsk)->inet6_rsk_offset dereference in inet6_rsk().
> > > 
> > > This is arguably not a critical error as the inet6_rsk_offset
> > > is only used to compute a pointer which is never really used
> > > (in the code path in question) anyway. But it might be a
> > > latent error, so let's fix it.
> > > 
> > > Spotted by kmemcheck.
> > 
> > Humm, so this was poisoned at allocation and then when inet6_rsk_offset
> > was accessed it noticed, interesting, thanks!
> > 
> > Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> 
> Good find :)  I'll add this to net-next-2.6, thanks!

nice - i think kmemcheck is starting to build up a healthy list of 
references :-)

	Ingo