do_ip_vs_set_ctl() is referencing uninitialized stack value when `len` is
zero. Fix it.
Reported-and-tested-by: [email protected]
Link: https://syzkaller.appspot.com/bug?id=46ebfb92a8a812621a001ef04d90dfa459520fe2
Signed-off-by: Peilin Ye <[email protected]>
---
net/netfilter/ipvs/ip_vs_ctl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 412656c34f20..c050b6a42786 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -2418,7 +2418,7 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
{
struct net *net = sock_net(sk);
int ret;
- unsigned char arg[MAX_SET_ARGLEN];
+ unsigned char arg[MAX_SET_ARGLEN] = {};
struct ip_vs_service_user *usvc_compat;
struct ip_vs_service_user_kern usvc;
struct ip_vs_service *svc;
--
2.25.1
On Mon, Aug 10, 2020 at 3:10 PM Peilin Ye <[email protected]> wrote:
>
> do_ip_vs_set_ctl() is referencing uninitialized stack value when `len` is
> zero. Fix it.
Which exact 'cmd' is it here?
I _guess_ it is one of those uninitialized in set_arglen[], which is 0.
But if that is the case, should it be initialized to
sizeof(struct ip_vs_service_user) instead because ip_vs_copy_usvc_compat()
is called anyway. Or, maybe we should just ban len==0 case.
In either case, it does not look like you fix it correctly.
Thanks.
On Mon, Aug 10, 2020 at 08:57:19PM -0700, Cong Wang wrote:
> On Mon, Aug 10, 2020 at 3:10 PM Peilin Ye <[email protected]> wrote:
> >
> > do_ip_vs_set_ctl() is referencing uninitialized stack value when `len` is
> > zero. Fix it.
>
> Which exact 'cmd' is it here?
>
> I _guess_ it is one of those uninitialized in set_arglen[], which is 0.
Yes, it was `IP_VS_SO_SET_NONE`, implicitly initialized to zero.
> But if that is the case, should it be initialized to
> sizeof(struct ip_vs_service_user) instead because ip_vs_copy_usvc_compat()
> is called anyway. Or, maybe we should just ban len==0 case.
I see. I think the latter would be easier, but we cannot ban all of
them, since the function does something with `IP_VS_SO_SET_FLUSH`, which
is a `len == 0` case.
Maybe we do something like this?
@@ -2432,6 +2432,8 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_SET_MAX)
return -EINVAL;
+ if (len == 0 && cmd != IP_VS_SO_SET_FLUSH)
+ return -EINVAL;
if (len != set_arglen[CMDID(cmd)]) {
IP_VS_DBG(1, "set_ctl: len %u != %u\n",
len, set_arglen[CMDID(cmd)]);
@@ -2547,9 +2549,6 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
break;
case IP_VS_SO_SET_DELDEST:
ret = ip_vs_del_dest(svc, &udest);
- break;
- default:
- ret = -EINVAL;
}
out_unlock:
Thank you,
Peilin Ye
> In either case, it does not look like you fix it correctly.
>
> Thanks.
Hello,
On Tue, 11 Aug 2020, Peilin Ye wrote:
> On Mon, Aug 10, 2020 at 08:57:19PM -0700, Cong Wang wrote:
> > On Mon, Aug 10, 2020 at 3:10 PM Peilin Ye <[email protected]> wrote:
> > >
> > > do_ip_vs_set_ctl() is referencing uninitialized stack value when `len` is
> > > zero. Fix it.
> >
> > Which exact 'cmd' is it here?
> >
> > I _guess_ it is one of those uninitialized in set_arglen[], which is 0.
>
> Yes, it was `IP_VS_SO_SET_NONE`, implicitly initialized to zero.
>
> > But if that is the case, should it be initialized to
> > sizeof(struct ip_vs_service_user) instead because ip_vs_copy_usvc_compat()
> > is called anyway. Or, maybe we should just ban len==0 case.
>
> I see. I think the latter would be easier, but we cannot ban all of
> them, since the function does something with `IP_VS_SO_SET_FLUSH`, which
> is a `len == 0` case.
>
> Maybe we do something like this?
Yes, only IP_VS_SO_SET_FLUSH uses len 0. We can go with
this change but you do not need to target net tree, as the
problem is not fatal net-next works too. What happens is
that we may lookup services with random search keys which
is harmless.
Another option is to add new block after this one:
} else if (cmd == IP_VS_SO_SET_TIMEOUT) {
/* Set timeout values for (tcp tcpfin udp) */
ret = ip_vs_set_timeout(ipvs, (struct ip_vs_timeout_user *)arg);
goto out_unlock;
}
such as:
} else if (!len) {
/* No more commands with len=0 below */
ret = -EINVAL;
goto out_unlock;
}
It give more chance for future commands to use len=0
but the drawback is that the check happens under mutex. So, I'm
fine with both versions, it is up to you to decide :)
> @@ -2432,6 +2432,8 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
>
> if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_SET_MAX)
> return -EINVAL;
> + if (len == 0 && cmd != IP_VS_SO_SET_FLUSH)
> + return -EINVAL;
> if (len != set_arglen[CMDID(cmd)]) {
> IP_VS_DBG(1, "set_ctl: len %u != %u\n",
> len, set_arglen[CMDID(cmd)]);
> @@ -2547,9 +2549,6 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
> break;
> case IP_VS_SO_SET_DELDEST:
> ret = ip_vs_del_dest(svc, &udest);
> - break;
> - default:
> - ret = -EINVAL;
> }
>
> out_unlock:
Regards
--
Julian Anastasov <[email protected]>
On Tue, Aug 11, 2020 at 09:58:46AM +0300, Julian Anastasov wrote:
>
> Hello,
>
> On Tue, 11 Aug 2020, Peilin Ye wrote:
>
> > On Mon, Aug 10, 2020 at 08:57:19PM -0700, Cong Wang wrote:
> > > On Mon, Aug 10, 2020 at 3:10 PM Peilin Ye <[email protected]> wrote:
> > > >
> > > > do_ip_vs_set_ctl() is referencing uninitialized stack value when `len` is
> > > > zero. Fix it.
> > >
> > > Which exact 'cmd' is it here?
> > >
> > > I _guess_ it is one of those uninitialized in set_arglen[], which is 0.
> >
> > Yes, it was `IP_VS_SO_SET_NONE`, implicitly initialized to zero.
> >
> > > But if that is the case, should it be initialized to
> > > sizeof(struct ip_vs_service_user) instead because ip_vs_copy_usvc_compat()
> > > is called anyway. Or, maybe we should just ban len==0 case.
> >
> > I see. I think the latter would be easier, but we cannot ban all of
> > them, since the function does something with `IP_VS_SO_SET_FLUSH`, which
> > is a `len == 0` case.
> >
> > Maybe we do something like this?
>
> Yes, only IP_VS_SO_SET_FLUSH uses len 0. We can go with
> this change but you do not need to target net tree, as the
> problem is not fatal net-next works too. What happens is
> that we may lookup services with random search keys which
> is harmless.
I see, I'll target net-next instead.
> Another option is to add new block after this one:
>
> } else if (cmd == IP_VS_SO_SET_TIMEOUT) {
> /* Set timeout values for (tcp tcpfin udp) */
> ret = ip_vs_set_timeout(ipvs, (struct ip_vs_timeout_user *)arg);
> goto out_unlock;
> }
>
> such as:
>
> } else if (!len) {
> /* No more commands with len=0 below */
> ret = -EINVAL;
> goto out_unlock;
> }
>
> It give more chance for future commands to use len=0
> but the drawback is that the check happens under mutex. So, I'm
> fine with both versions, it is up to you to decide :)
Ah, this seems much cleaner. I'll send v2 soon, thank you!
Peilin Ye
> > @@ -2432,6 +2432,8 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
> >
> > if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_SET_MAX)
> > return -EINVAL;
> > + if (len == 0 && cmd != IP_VS_SO_SET_FLUSH)
> > + return -EINVAL;
> > if (len != set_arglen[CMDID(cmd)]) {
> > IP_VS_DBG(1, "set_ctl: len %u != %u\n",
> > len, set_arglen[CMDID(cmd)]);
> > @@ -2547,9 +2549,6 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
> > break;
> > case IP_VS_SO_SET_DELDEST:
> > ret = ip_vs_del_dest(svc, &udest);
> > - break;
> > - default:
> > - ret = -EINVAL;
> > }
> >
> > out_unlock:
>
> Regards
>
> --
> Julian Anastasov <[email protected]>
do_ip_vs_set_ctl() is referencing uninitialized stack value when `len` is
zero. Fix it.
Reported-by: [email protected]
Link: https://syzkaller.appspot.com/bug?id=46ebfb92a8a812621a001ef04d90dfa459520fe2
Suggested-by: Julian Anastasov <[email protected]>
Signed-off-by: Peilin Ye <[email protected]>
---
Changes in v2:
- Target net-next tree. (Suggested by Julian Anastasov <[email protected]>)
- Reject all `len == 0` requests except `IP_VS_SO_SET_FLUSH`, instead
of initializing `arg`. (Suggested by Cong Wang
<[email protected]>, Julian Anastasov <[email protected]>)
net/netfilter/ipvs/ip_vs_ctl.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 412656c34f20..beeafa42aad7 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -2471,6 +2471,10 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
/* Set timeout values for (tcp tcpfin udp) */
ret = ip_vs_set_timeout(ipvs, (struct ip_vs_timeout_user *)arg);
goto out_unlock;
+ } else if (!len) {
+ /* No more commands with len == 0 below */
+ ret = -EINVAL;
+ goto out_unlock;
}
usvc_compat = (struct ip_vs_service_user *)arg;
@@ -2547,9 +2551,6 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
break;
case IP_VS_SO_SET_DELDEST:
ret = ip_vs_del_dest(svc, &udest);
- break;
- default:
- ret = -EINVAL;
}
out_unlock:
--
2.25.1
Hello,
On Tue, 11 Aug 2020, Peilin Ye wrote:
> do_ip_vs_set_ctl() is referencing uninitialized stack value when `len` is
> zero. Fix it.
>
> Reported-by: [email protected]
> Link: https://syzkaller.appspot.com/bug?id=46ebfb92a8a812621a001ef04d90dfa459520fe2
> Suggested-by: Julian Anastasov <[email protected]>
> Signed-off-by: Peilin Ye <[email protected]>
Looks good to me, thanks!
Acked-by: Julian Anastasov <[email protected]>
> ---
> Changes in v2:
> - Target net-next tree. (Suggested by Julian Anastasov <[email protected]>)
> - Reject all `len == 0` requests except `IP_VS_SO_SET_FLUSH`, instead
> of initializing `arg`. (Suggested by Cong Wang
> <[email protected]>, Julian Anastasov <[email protected]>)
>
> net/netfilter/ipvs/ip_vs_ctl.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index 412656c34f20..beeafa42aad7 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -2471,6 +2471,10 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
> /* Set timeout values for (tcp tcpfin udp) */
> ret = ip_vs_set_timeout(ipvs, (struct ip_vs_timeout_user *)arg);
> goto out_unlock;
> + } else if (!len) {
> + /* No more commands with len == 0 below */
> + ret = -EINVAL;
> + goto out_unlock;
> }
>
> usvc_compat = (struct ip_vs_service_user *)arg;
> @@ -2547,9 +2551,6 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
> break;
> case IP_VS_SO_SET_DELDEST:
> ret = ip_vs_del_dest(svc, &udest);
> - break;
> - default:
> - ret = -EINVAL;
> }
>
> out_unlock:
> --
> 2.25.1
Regards
--
Julian Anastasov <[email protected]>
On Tue, Aug 11, 2020 at 01:29:04PM +0300, Julian Anastasov wrote:
>
> Hello,
>
> On Tue, 11 Aug 2020, Peilin Ye wrote:
>
> > do_ip_vs_set_ctl() is referencing uninitialized stack value when `len` is
> > zero. Fix it.
> >
> > Reported-by: [email protected]
> > Link: https://syzkaller.appspot.com/bug?id=46ebfb92a8a812621a001ef04d90dfa459520fe2
> > Suggested-by: Julian Anastasov <[email protected]>
> > Signed-off-by: Peilin Ye <[email protected]>
>
> Looks good to me, thanks!
>
> Acked-by: Julian Anastasov <[email protected]>
Pablo, could you consider this for nf-next or should we repost when
net-next re-opens?
Reviewed-by: Simon Horman <[email protected]>
On Tue, Aug 11, 2020 at 02:59:59PM +0200, Simon Horman wrote:
> On Tue, Aug 11, 2020 at 01:29:04PM +0300, Julian Anastasov wrote:
> >
> > Hello,
> >
> > On Tue, 11 Aug 2020, Peilin Ye wrote:
> >
> > > do_ip_vs_set_ctl() is referencing uninitialized stack value when `len` is
> > > zero. Fix it.
> > >
> > > Reported-by: [email protected]
> > > Link: https://syzkaller.appspot.com/bug?id=46ebfb92a8a812621a001ef04d90dfa459520fe2
> > > Suggested-by: Julian Anastasov <[email protected]>
> > > Signed-off-by: Peilin Ye <[email protected]>
> >
> > Looks good to me, thanks!
> >
> > Acked-by: Julian Anastasov <[email protected]>
>
> Pablo, could you consider this for nf-next or should we repost when
> net-next re-opens?
No worries, it will sit in netfilter's patchwork until net-next
reopens.
On Tue, Aug 11, 2020 at 03:46:40AM -0400, Peilin Ye wrote:
> do_ip_vs_set_ctl() is referencing uninitialized stack value when `len` is
> zero. Fix it.
Applied to nf-next, thanks.