2018-10-27 20:21:36

by Tomas Bortoli

Subject: [PATCH] sctp: socket.c validate sprstat_policy

It is possible to perform out-of-bound reads on
sctp_getsockopt_pr_streamstatus() and on
sctp_getsockopt_pr_assocstatus() by passing from userspace a
sprstat_policy that overflows the abandoned_sent/abandoned_unsent
fixed length arrays. The over-read data are directly copied/leaked
to userspace.

Signed-off-by: Tomas Bortoli <[email protected]>
Reported-by: [email protected]
---
v2 - added forgot ||

net/sctp/socket.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index fc0386e8ff23..5290b8bd40c8 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -7083,7 +7083,8 @@ static int sctp_getsockopt_pr_assocstatus(struct sock *sk, int len,
}

policy = params.sprstat_policy;
- if (!policy || (policy & ~(SCTP_PR_SCTP_MASK | SCTP_PR_SCTP_ALL)))
+ if (!policy || (policy & ~(SCTP_PR_SCTP_MASK | SCTP_PR_SCTP_ALL)) ||
+ __SCTP_PR_INDEX(policy) > SCTP_PR_INDEX(MAX))
goto out;

asoc = sctp_id2assoc(sk, params.sprstat_assoc_id);
@@ -7142,7 +7143,8 @@ static int sctp_getsockopt_pr_streamstatus(struct sock *sk, int len,
}

policy = params.sprstat_policy;
- if (!policy || (policy & ~(SCTP_PR_SCTP_MASK | SCTP_PR_SCTP_ALL)))
+ if (!policy || (policy & ~(SCTP_PR_SCTP_MASK | SCTP_PR_SCTP_ALL)) ||
+ __SCTP_PR_INDEX(policy) > SCTP_PR_INDEX(MAX))
goto out;

asoc = sctp_id2assoc(sk, params.sprstat_assoc_id);
--
2.11.0

2018-10-27 20:53:51

by Tomas Bortoli

Subject: Re: [PATCH] sctp: socket.c validate sprstat_policy

On 10/27/18 10:20 PM, Tomas Bortoli wrote:
> It is possible to perform out-of-bound reads on
> sctp_getsockopt_pr_streamstatus() and on
> sctp_getsockopt_pr_assocstatus() by passing from userspace a
> sprstat_policy that overflows the abandoned_sent/abandoned_unsent
> fixed length arrays. The over-read data are directly copied/leaked
> to userspace.
>
> Signed-off-by: Tomas Bortoli <[email protected]>
> Reported-by: [email protected]
> ---
> v2 - added forgot ||
>
> net/sctp/socket.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index fc0386e8ff23..5290b8bd40c8 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -7083,7 +7083,8 @@ static int sctp_getsockopt_pr_assocstatus(struct sock *sk, int len,
> }
>
> policy = params.sprstat_policy;
> - if (!policy || (policy & ~(SCTP_PR_SCTP_MASK | SCTP_PR_SCTP_ALL)))
> + if (!policy || (policy & ~(SCTP_PR_SCTP_MASK | SCTP_PR_SCTP_ALL)) ||
> + __SCTP_PR_INDEX(policy) > SCTP_PR_INDEX(MAX))
> goto out;
>
> asoc = sctp_id2assoc(sk, params.sprstat_assoc_id);
> @@ -7142,7 +7143,8 @@ static int sctp_getsockopt_pr_streamstatus(struct sock *sk, int len,
> }
>
> policy = params.sprstat_policy;
> - if (!policy || (policy & ~(SCTP_PR_SCTP_MASK | SCTP_PR_SCTP_ALL)))
> + if (!policy || (policy & ~(SCTP_PR_SCTP_MASK | SCTP_PR_SCTP_ALL)) ||
> + __SCTP_PR_INDEX(policy) > SCTP_PR_INDEX(MAX))
> goto out;
>
> asoc = sctp_id2assoc(sk, params.sprstat_assoc_id);
>

I just realized we also have to check for less than 0 indexes..

2018-10-28 00:11:30

by David Miller

Subject: Re: [PATCH] sctp: socket.c validate sprstat_policy

From: Tomas Bortoli <[email protected]>
Date: Sat, 27 Oct 2018 22:43:43 +0200

> I just realized we also have to check for less than 0 indexes..

How about the fact that your original submission didn't even compile?

I hope you realized that first.