2019-03-04 03:49:17

by Su, Yanjun

Subject: [PATCH] net: xfrm: Fix potential oops in xfrm_user_rcv_msg and array out of bounds

When i review xfrm_user.c code, i found some potentical bug in it.

In xfrm_user_rcvmsg if type parameter from user space is set to
XFRM_MSG_MAX or XFRM_MSG_NEWSADINFO or XFRM_MSG_NEWSPDINFO. It will cause
xfrm_user_rcv_msg referring to null entry in xfrm_dispatch array.

Signed-off-by: Su Yanjun <[email protected]>
---
net/xfrm/xfrm_user.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index a131f9f..d832783 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -2630,11 +2630,13 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
return -EOPNOTSUPP;

type = nlh->nlmsg_type;
- if (type > XFRM_MSG_MAX)
+ if (type >= XFRM_MSG_MAX)
return -EINVAL;

type -= XFRM_MSG_BASE;
link = &xfrm_dispatch[type];
+ if (!link)
+ return -EOPNOTSUPP;

/* All operations require privileges, even GET */
if (!netlink_net_capable(skb, CAP_NET_ADMIN))
--
2.7.4

2019-03-05 06:50:41

by Herbert Xu

Subject: Re: [PATCH] net: xfrm: Fix potential oops in xfrm_user_rcv_msg and array out of bounds

On Sun, Mar 03, 2019 at 10:47:39PM -0500, Su Yanjun wrote:
> When i review xfrm_user.c code, i found some potentical bug in it.
>
> In xfrm_user_rcvmsg if type parameter from user space is set to
> XFRM_MSG_MAX or XFRM_MSG_NEWSADINFO or XFRM_MSG_NEWSPDINFO. It will cause
> xfrm_user_rcv_msg referring to null entry in xfrm_dispatch array.
>
> Signed-off-by: Su Yanjun <[email protected]>
> ---
> net/xfrm/xfrm_user.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
> index a131f9f..d832783 100644
> --- a/net/xfrm/xfrm_user.c
> +++ b/net/xfrm/xfrm_user.c
> @@ -2630,11 +2630,13 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
> return -EOPNOTSUPP;
>
> type = nlh->nlmsg_type;
> - if (type > XFRM_MSG_MAX)
> + if (type >= XFRM_MSG_MAX)
> return -EINVAL;

Your patch is wrong. Please check the definition of XFRM_MSG_MAX.

Thanks,
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

2019-03-05 07:31:56

by Steffen Klassert

Subject: Re: [PATCH] net: xfrm: Fix potential oops in xfrm_user_rcv_msg and array out of bounds

On Tue, Mar 05, 2019 at 03:08:49PM +0800, Su Yanjun <[email protected]> wrote:
> On 2019/3/5 14:49, Herbert Xu wrote:
>
> > On Sun, Mar 03, 2019 at 10:47:39PM -0500, Su Yanjun wrote:
> > > When i review xfrm_user.c code, i found some potentical bug in it.
> > >
> > > In xfrm_user_rcvmsg if type parameter from user space is set to
> > > XFRM_MSG_MAX or XFRM_MSG_NEWSADINFO or XFRM_MSG_NEWSPDINFO. It will cause
> > > xfrm_user_rcv_msg referring to null entry in xfrm_dispatch array.
> > >
> > > Signed-off-by: Su Yanjun <[email protected]>
> > > ---
> > > net/xfrm/xfrm_user.c | 4 +++-
> > > 1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
> > > index a131f9f..d832783 100644
> > > --- a/net/xfrm/xfrm_user.c
> > > +++ b/net/xfrm/xfrm_user.c
> > > @@ -2630,11 +2630,13 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
> > > return -EOPNOTSUPP;
> > > type = nlh->nlmsg_type;
> > > - if (type > XFRM_MSG_MAX)
> > > + if (type >= XFRM_MSG_MAX)
> > > return -EINVAL;
> > Your patch is wrong. Please check the definition of XFRM_MSG_MAX.
>
> I see, thanks for your reply.
>
> type -= XFRM_MSG_BASE;
> link = &xfrm_dispatch[type];
> + if (!link)
> + return -EOPNOTSUPP;
>
> Here **link** may refer to null entry for special types such as
> XFRM_MSG_MAX or XFRM_MSG_NEWSADINFO or XFRM_MSG_NEWSPDINFO
> Am i miss something?

'link' is always a valid pointer into that array.

2019-03-05 07:39:59

by Su, Yanjun

Subject: Re: [PATCH] net: xfrm: Fix potential oops in xfrm_user_rcv_msg and array out of bounds

On 2019/3/5 15:31, Steffen Klassert wrote:
> On Tue, Mar 05, 2019 at 03:08:49PM +0800, Su Yanjun <[email protected]> wrote:
>> On 2019/3/5 14:49, Herbert Xu wrote:
>>
>>> On Sun, Mar 03, 2019 at 10:47:39PM -0500, Su Yanjun wrote:
>>>> When i review xfrm_user.c code, i found some potentical bug in it.
>>>>
>>>> In xfrm_user_rcvmsg if type parameter from user space is set to
>>>> XFRM_MSG_MAX or XFRM_MSG_NEWSADINFO or XFRM_MSG_NEWSPDINFO. It will cause
>>>> xfrm_user_rcv_msg referring to null entry in xfrm_dispatch array.
>>>>
>>>> Signed-off-by: Su Yanjun <[email protected]>
>>>> ---
>>>> net/xfrm/xfrm_user.c | 4 +++-
>>>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
>>>> index a131f9f..d832783 100644
>>>> --- a/net/xfrm/xfrm_user.c
>>>> +++ b/net/xfrm/xfrm_user.c
>>>> @@ -2630,11 +2630,13 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
>>>> return -EOPNOTSUPP;
>>>> type = nlh->nlmsg_type;
>>>> - if (type > XFRM_MSG_MAX)
>>>> + if (type >= XFRM_MSG_MAX)
>>>> return -EINVAL;
>>> Your patch is wrong. Please check the definition of XFRM_MSG_MAX.
>> I see, thanks for your reply.
>>
>> type -= XFRM_MSG_BASE;
>> link = &xfrm_dispatch[type];
>> + if (!link)
>> + return -EOPNOTSUPP;
>>
>> Here **link** may refer to null entry for special types such as
>> XFRM_MSG_MAX or XFRM_MSG_NEWSADINFO or XFRM_MSG_NEWSPDINFO
>> Am i miss something?
> 'link' is always a valid pointer into that array.

Thanks

Su