2018-10-27 20:55:12

by Tomas Bortoli

Subject: [PATCH v2] 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]
---
net/sctp/socket.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index fc0386e8ff23..14dce5d95817 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -7083,7 +7083,9 @@ 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) ||
+ __SCTP_PR_INDEX(policy) < 0)
goto out;

asoc = sctp_id2assoc(sk, params.sprstat_assoc_id);
@@ -7142,7 +7144,9 @@ 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) ||
+ __SCTP_PR_INDEX(policy) < 0)
goto out;

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

2018-10-28 04:21:24

by Xin Long

Subject: Re: [PATCH v2] sctp: socket.c validate sprstat_policy

On Sun, Oct 28, 2018 at 5:54 AM Tomas Bortoli <[email protected]> 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]
> ---
> net/sctp/socket.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index fc0386e8ff23..14dce5d95817 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -7083,7 +7083,9 @@ 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) ||
> + __SCTP_PR_INDEX(policy) < 0)
> goto out;
>
> asoc = sctp_id2assoc(sk, params.sprstat_assoc_id);
> @@ -7142,7 +7144,9 @@ 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) ||
> + __SCTP_PR_INDEX(policy) < 0)
> goto out;
This is not the correct fix.
See https://lkml.org/lkml/2018/10/27/136

2018-10-28 09:02:09

by Tomas Bortoli

Subject: Re: [PATCH v2] sctp: socket.c validate sprstat_policy

On 10/28/18 5:17 AM, Xin Long wrote:
> On Sun, Oct 28, 2018 at 5:54 AM Tomas Bortoli <[email protected]> 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]
>> ---
>> net/sctp/socket.c | 8 ++++++--
>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
>> index fc0386e8ff23..14dce5d95817 100644
>> --- a/net/sctp/socket.c
>> +++ b/net/sctp/socket.c
>> @@ -7083,7 +7083,9 @@ 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) ||
>> + __SCTP_PR_INDEX(policy) < 0)
>> goto out;
>>
>> asoc = sctp_id2assoc(sk, params.sprstat_assoc_id);
>> @@ -7142,7 +7144,9 @@ 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) ||
>> + __SCTP_PR_INDEX(policy) < 0)
>> goto out;
> This is not the correct fix.
> See https://lkml.org/lkml/2018/10/27/136
>

Ack, good to know ty!