[patch -mainline] netfilter: ipset: small potential read beyond the end of buffer

[patch -mainline] netfilter: ipset: small potential read beyond the end of buffer

[Dan Carpenter]

We could be reading 8 bytes into a 4 byte buffer here.  It seems
harmless but adding a check is the right thing to do and it silences a
static checker warning.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
index 86f9d76..ac08a3f 100644
--- a/net/netfilter/ipset/ip_set_core.c
+++ b/net/netfilter/ipset/ip_set_core.c
@@ -1863,7 +1863,8 @@ ip_set_sockfn_get(struct sock *sk, int optval, void __user *user, int *len)
 	if (*op < IP_SET_OP_VERSION) {
 		/* Check the version at the beginning of operations */
 		struct ip_set_req_version *req_version = data;
-		if (req_version->version != IPSET_PROTOCOL) {
+		if (*len < sizeof(struct ip_set_req_version) ||
+		    req_version->version != IPSET_PROTOCOL) {
 			ret = -EPROTO;
 			goto done;
 		}

Re: [patch -mainline] netfilter: ipset: small potential read beyond the end of buffer

[Pablo Neira Ayuso]

On Fri, Nov 07, 2014 at 09:21:40AM +0300, Dan Carpenter wrote:
> We could be reading 8 bytes into a 4 byte buffer here.  It seems
> harmless but adding a check is the right thing to do and it silences a
> static checker warning.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
> index 86f9d76..ac08a3f 100644
> --- a/net/netfilter/ipset/ip_set_core.c
> +++ b/net/netfilter/ipset/ip_set_core.c
> @@ -1863,7 +1863,8 @@ ip_set_sockfn_get(struct sock *sk, int optval, void __user *user, int *len)
>  	if (*op < IP_SET_OP_VERSION) {
>  		/* Check the version at the beginning of operations */
>  		struct ip_set_req_version *req_version = data;
> -		if (req_version->version != IPSET_PROTOCOL) {
> +		if (*len < sizeof(struct ip_set_req_version) ||
> +		    req_version->version != IPSET_PROTOCOL) {
>  			ret = -EPROTO;
>  			goto done;

Thanks for catching up this.

>From other similar code in that location, I can see Jozsef is using
this pattern:

                if (*len != sizeof(struct ip_set_req_version)) {
                        ret = -EINVAL;
                        goto done;
                }

I think it would be good to stick to that for consistency. Thanks.

Re: [patch -mainline] netfilter: ipset: small potential read beyond the end of buffer

[Jozsef Kadlecsik]

On Mon, 10 Nov 2014, Pablo Neira Ayuso wrote:

> On Fri, Nov 07, 2014 at 09:21:40AM +0300, Dan Carpenter wrote:
> > We could be reading 8 bytes into a 4 byte buffer here.  It seems
> > harmless but adding a check is the right thing to do and it silences a
> > static checker warning.
> > 
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > 
> > diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
> > index 86f9d76..ac08a3f 100644
> > --- a/net/netfilter/ipset/ip_set_core.c
> > +++ b/net/netfilter/ipset/ip_set_core.c
> > @@ -1863,7 +1863,8 @@ ip_set_sockfn_get(struct sock *sk, int optval, void __user *user, int *len)
> >  	if (*op < IP_SET_OP_VERSION) {
> >  		/* Check the version at the beginning of operations */
> >  		struct ip_set_req_version *req_version = data;
> > -		if (req_version->version != IPSET_PROTOCOL) {
> > +		if (*len < sizeof(struct ip_set_req_version) ||
> > +		    req_version->version != IPSET_PROTOCOL) {
> >  			ret = -EPROTO;
> >  			goto done;
> 
> Thanks for catching up this.
> 
> >From other similar code in that location, I can see Jozsef is using
> this pattern:
> 
>                 if (*len != sizeof(struct ip_set_req_version)) {
>                         ret = -EINVAL;
>                         goto done;
>                 }
> 
> I think it would be good to stick to that for consistency. Thanks.

Absolutely, yes.

Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>

Best regards,
Jozsef
-
E-mail  : kadlec@blackhole.kfki.hu, kadlecsik.jozsef@wigner.mta.hu
PGP key : http://www.kfki.hu/~kadlec/pgp_public_key.txt
Address : Wigner Research Centre for Physics, Hungarian Academy of Sciences
          H-1525 Budapest 114, POB. 49, Hungary

Re: [patch -mainline] netfilter: ipset: small potential read beyond the end of buffer

[Pablo Neira Ayuso]

[-- Attachment #1: Type: text/plain, Size: 653 bytes --]

On Mon, Nov 10, 2014 at 03:27:51PM +0100, Jozsef Kadlecsik wrote:
> On Mon, 10 Nov 2014, Pablo Neira Ayuso wrote:
> > >From other similar code in that location, I can see Jozsef is using
> > this pattern:
> > 
> >                 if (*len != sizeof(struct ip_set_req_version)) {
> >                         ret = -EINVAL;
> >                         goto done;
> >                 }
> > 
> > I think it would be good to stick to that for consistency. Thanks.
> 
> Absolutely, yes.
> 
> Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>

OK, then does this look fine to you? I took over Dan's patch and gave
it another spin. See it attached, thanks.

[-- Attachment #2: 0001-netfilter-ipset-small-potential-read-beyond-the-end-.patch --]
[-- Type: text/x-diff, Size: 1222 bytes --]

>From d67bad383d4ea9dea8872e3999324ccbeb2a5815 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Fri, 7 Nov 2014 09:21:40 +0300
Subject: [PATCH] netfilter: ipset: small potential read beyond the end of
 buffer

We could be reading 8 bytes into a 4 byte buffer here.  It seems
harmless but adding a check is the right thing to do and it silences a
static checker warning.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/ipset/ip_set_core.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
index 86f9d76..d259da3 100644
--- a/net/netfilter/ipset/ip_set_core.c
+++ b/net/netfilter/ipset/ip_set_core.c
@@ -1863,6 +1863,12 @@ ip_set_sockfn_get(struct sock *sk, int optval, void __user *user, int *len)
 	if (*op < IP_SET_OP_VERSION) {
 		/* Check the version at the beginning of operations */
 		struct ip_set_req_version *req_version = data;
+
+		if (*len < sizeof(struct ip_set_req_version)) {
+			ret = -EINVAL;
+			goto done;
+		}
+
 		if (req_version->version != IPSET_PROTOCOL) {
 			ret = -EPROTO;
 			goto done;
-- 
1.7.10.4

Re: [patch -mainline] netfilter: ipset: small potential read beyond the end of buffer

[Jozsef Kadlecsik]

On Mon, 10 Nov 2014, Pablo Neira Ayuso wrote:

> On Mon, Nov 10, 2014 at 03:27:51PM +0100, Jozsef Kadlecsik wrote:
> > On Mon, 10 Nov 2014, Pablo Neira Ayuso wrote:
> > > >From other similar code in that location, I can see Jozsef is using
> > > this pattern:
> > > 
> > >                 if (*len != sizeof(struct ip_set_req_version)) {
> > >                         ret = -EINVAL;
> > >                         goto done;
> > >                 }
> > > 
> > > I think it would be good to stick to that for consistency. Thanks.
> > 
> > Absolutely, yes.
> > 
> > Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
> 
> OK, then does this look fine to you? I took over Dan's patch and gave
> it another spin. See it attached, thanks.

Yes, it's better this way, thanks!

Best regards,
Jozsef
-
E-mail  : kadlec@blackhole.kfki.hu, kadlecsik.jozsef@wigner.mta.hu
PGP key : http://www.kfki.hu/~kadlec/pgp_public_key.txt
Address : Wigner Research Centre for Physics, Hungarian Academy of Sciences
          H-1525 Budapest 114, POB. 49, Hungary

Re: [patch -mainline] netfilter: ipset: small potential read beyond the end of buffer

[Pablo Neira Ayuso]

On Mon, Nov 10, 2014 at 10:00:20PM +0100, Jozsef Kadlecsik wrote:
> On Mon, 10 Nov 2014, Pablo Neira Ayuso wrote:
> 
> > On Mon, Nov 10, 2014 at 03:27:51PM +0100, Jozsef Kadlecsik wrote:
> > > On Mon, 10 Nov 2014, Pablo Neira Ayuso wrote:
> > > > >From other similar code in that location, I can see Jozsef is using
> > > > this pattern:
> > > > 
> > > >                 if (*len != sizeof(struct ip_set_req_version)) {
> > > >                         ret = -EINVAL;
> > > >                         goto done;
> > > >                 }
> > > > 
> > > > I think it would be good to stick to that for consistency. Thanks.
> > > 
> > > Absolutely, yes.
> > > 
> > > Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
> > 
> > OK, then does this look fine to you? I took over Dan's patch and gave
> > it another spin. See it attached, thanks.
> 
> Yes, it's better this way, thanks!

Applied, thanks Dan and Jozsef.

Re: [patch -mainline] netfilter: ipset: small potential read beyond the end of buffer

[Dan Carpenter]

On Mon, Nov 10, 2014 at 05:11:21PM +0100, Pablo Neira Ayuso wrote:

> OK, then does this look fine to you? I took over Dan's patch and gave
> it another spin. See it attached, thanks.

Looks good to me, thanks.

regards,
dan carpenter