In sctp_setsockopt_maxseg(), the integer 'val' is compared against min_len
and max_len to check whether it is in the appropriate range. If it is not,
an error code -EINVAL will be returned. This is enforced by a security
check. But, this check is only executed when 'val' is not 0. In fact, if
'val' is 0, it will be assigned with a new value (if the return value of
the function sctp_id2assoc() is not 0) in the following execution. However,
this new value of 'val' is not checked before it is used to assigned to
asoc->user_frag. That means it is possible that the new value of 'val'
could be out of the expected range. This can cause security issues
such as buffer overflows, e.g., the new value of 'val' is used as an index
to access a buffer.
This patch inserts a check for the new value of 'val' to see if it is in
the expected range. If it is not, an error code -EINVAL will be returned.
Signed-off-by: Wenwen Wang <[email protected]>
---
net/sctp/socket.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 80835ac..03e1cc3 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -3212,6 +3212,7 @@ static int sctp_setsockopt_maxseg(struct sock *sk, char __user *optval, unsigned
struct sctp_af *af = sp->pf->af;
struct sctp_assoc_value params;
struct sctp_association *asoc;
+ int min_len, max_len;
int val;
if (optlen == sizeof(int)) {
@@ -3231,19 +3232,15 @@ static int sctp_setsockopt_maxseg(struct sock *sk, char __user *optval, unsigned
return -EINVAL;
}
- if (val) {
- int min_len, max_len;
+ min_len = SCTP_DEFAULT_MINSEGMENT - af->net_header_len;
+ min_len -= af->ip_options_len(sk);
+ min_len -= sizeof(struct sctphdr) +
+ sizeof(struct sctp_data_chunk);
- min_len = SCTP_DEFAULT_MINSEGMENT - af->net_header_len;
- min_len -= af->ip_options_len(sk);
- min_len -= sizeof(struct sctphdr) +
- sizeof(struct sctp_data_chunk);
+ max_len = SCTP_MAX_CHUNK_LEN - sizeof(struct sctp_data_chunk);
- max_len = SCTP_MAX_CHUNK_LEN - sizeof(struct sctp_data_chunk);
-
- if (val < min_len || val > max_len)
- return -EINVAL;
- }
+ if (val && (val < min_len || val > max_len))
+ return -EINVAL;
asoc = sctp_id2assoc(sk, params.assoc_id);
if (asoc) {
@@ -3253,6 +3250,9 @@ static int sctp_setsockopt_maxseg(struct sock *sk, char __user *optval, unsigned
val -= sizeof(struct sctphdr) +
sctp_datachk_len(&asoc->stream);
}
+ /* Check the new val to make sure it is in the range. */
+ if (val < min_len || val > max_len)
+ return -EINVAL;
asoc->user_frag = val;
asoc->frag_point = sctp_frag_point(asoc, asoc->pathmtu);
} else {
--
2.7.4
On Wed, May 02, 2018 at 08:15:45PM -0500, Wenwen Wang wrote:
> In sctp_setsockopt_maxseg(), the integer 'val' is compared against min_len
> and max_len to check whether it is in the appropriate range. If it is not,
> an error code -EINVAL will be returned. This is enforced by a security
> check. But, this check is only executed when 'val' is not 0. In fact, if
> 'val' is 0, it will be assigned with a new value (if the return value of
> the function sctp_id2assoc() is not 0) in the following execution. However,
> this new value of 'val' is not checked before it is used to assigned to
> asoc->user_frag. That means it is possible that the new value of 'val'
> could be out of the expected range. This can cause security issues
> such as buffer overflows, e.g., the new value of 'val' is used as an index
> to access a buffer.
>
> This patch inserts a check for the new value of 'val' to see if it is in
> the expected range. If it is not, an error code -EINVAL will be returned.
>
> Signed-off-by: Wenwen Wang <[email protected]>
> ---
> net/sctp/socket.c | 22 +++++++++++-----------
> 1 file changed, 11 insertions(+), 11 deletions(-)
?
This patch is the same as previous one. git send-email <old file>
maybe?
Marcelo
On Wed, May 2, 2018 at 8:24 PM, Marcelo Ricardo Leitner
<[email protected]> wrote:
> On Wed, May 02, 2018 at 08:15:45PM -0500, Wenwen Wang wrote:
>> In sctp_setsockopt_maxseg(), the integer 'val' is compared against min_len
>> and max_len to check whether it is in the appropriate range. If it is not,
>> an error code -EINVAL will be returned. This is enforced by a security
>> check. But, this check is only executed when 'val' is not 0. In fact, if
>> 'val' is 0, it will be assigned with a new value (if the return value of
>> the function sctp_id2assoc() is not 0) in the following execution. However,
>> this new value of 'val' is not checked before it is used to assigned to
>> asoc->user_frag. That means it is possible that the new value of 'val'
>> could be out of the expected range. This can cause security issues
>> such as buffer overflows, e.g., the new value of 'val' is used as an index
>> to access a buffer.
>>
>> This patch inserts a check for the new value of 'val' to see if it is in
>> the expected range. If it is not, an error code -EINVAL will be returned.
>>
>> Signed-off-by: Wenwen Wang <[email protected]>
>> ---
>> net/sctp/socket.c | 22 +++++++++++-----------
>> 1 file changed, 11 insertions(+), 11 deletions(-)
>
> ?
> This patch is the same as previous one. git send-email <old file>
> maybe?
>
> Marcelo
Thanks for your suggestion, Marcelo. I can send the old file. But, I
have added a line of comment in this patch.
Wenwen
On Wed, May 02, 2018 at 08:27:05PM -0500, Wenwen Wang wrote:
> On Wed, May 2, 2018 at 8:24 PM, Marcelo Ricardo Leitner
> <[email protected]> wrote:
> > On Wed, May 02, 2018 at 08:15:45PM -0500, Wenwen Wang wrote:
> >> In sctp_setsockopt_maxseg(), the integer 'val' is compared against min_len
> >> and max_len to check whether it is in the appropriate range. If it is not,
> >> an error code -EINVAL will be returned. This is enforced by a security
> >> check. But, this check is only executed when 'val' is not 0. In fact, if
> >> 'val' is 0, it will be assigned with a new value (if the return value of
> >> the function sctp_id2assoc() is not 0) in the following execution. However,
> >> this new value of 'val' is not checked before it is used to assigned to
> >> asoc->user_frag. That means it is possible that the new value of 'val'
> >> could be out of the expected range. This can cause security issues
> >> such as buffer overflows, e.g., the new value of 'val' is used as an index
> >> to access a buffer.
> >>
> >> This patch inserts a check for the new value of 'val' to see if it is in
> >> the expected range. If it is not, an error code -EINVAL will be returned.
> >>
> >> Signed-off-by: Wenwen Wang <[email protected]>
> >> ---
> >> net/sctp/socket.c | 22 +++++++++++-----------
> >> 1 file changed, 11 insertions(+), 11 deletions(-)
> >
> > ?
> > This patch is the same as previous one. git send-email <old file>
> > maybe?
> >
> > Marcelo
>
> Thanks for your suggestion, Marcelo. I can send the old file. But, I
> have added a line of comment in this patch.
I meant if you had sent the old patch again by accident, because you
said you worked on an old version of the tree, but then posted a patch
that also doesn't use the new MTU function I mentioned.
Marcelo
On Wed, May 2, 2018 at 8:48 PM, Marcelo Ricardo Leitner
<[email protected]> wrote:
> On Wed, May 02, 2018 at 08:27:05PM -0500, Wenwen Wang wrote:
>> On Wed, May 2, 2018 at 8:24 PM, Marcelo Ricardo Leitner
>> <[email protected]> wrote:
>> > On Wed, May 02, 2018 at 08:15:45PM -0500, Wenwen Wang wrote:
>> >> In sctp_setsockopt_maxseg(), the integer 'val' is compared against min_len
>> >> and max_len to check whether it is in the appropriate range. If it is not,
>> >> an error code -EINVAL will be returned. This is enforced by a security
>> >> check. But, this check is only executed when 'val' is not 0. In fact, if
>> >> 'val' is 0, it will be assigned with a new value (if the return value of
>> >> the function sctp_id2assoc() is not 0) in the following execution. However,
>> >> this new value of 'val' is not checked before it is used to assigned to
>> >> asoc->user_frag. That means it is possible that the new value of 'val'
>> >> could be out of the expected range. This can cause security issues
>> >> such as buffer overflows, e.g., the new value of 'val' is used as an index
>> >> to access a buffer.
>> >>
>> >> This patch inserts a check for the new value of 'val' to see if it is in
>> >> the expected range. If it is not, an error code -EINVAL will be returned.
>> >>
>> >> Signed-off-by: Wenwen Wang <[email protected]>
>> >> ---
>> >> net/sctp/socket.c | 22 +++++++++++-----------
>> >> 1 file changed, 11 insertions(+), 11 deletions(-)
>> >
>> > ?
>> > This patch is the same as previous one. git send-email <old file>
>> > maybe?
>> >
>> > Marcelo
>>
>> Thanks for your suggestion, Marcelo. I can send the old file. But, I
>> have added a line of comment in this patch.
>
> I meant if you had sent the old patch again by accident, because you
> said you worked on an old version of the tree, but then posted a patch
> that also doesn't use the new MTU function I mentioned.
>
> Marcelo
I worked on the latest kernel. But, I didn't find the MTU function
sctp_mtu_payload().
The problematic function that I found is sctp_setsockopt_maxseg()
located in the file net/sctp/socket.c.
Thanks,
Wenwen
On Thu, May 03, 2018 at 07:01:51AM -0500, Wenwen Wang wrote:
> On Wed, May 2, 2018 at 8:48 PM, Marcelo Ricardo Leitner
> <[email protected]> wrote:
> > On Wed, May 02, 2018 at 08:27:05PM -0500, Wenwen Wang wrote:
> >> On Wed, May 2, 2018 at 8:24 PM, Marcelo Ricardo Leitner
> >> <[email protected]> wrote:
> >> > On Wed, May 02, 2018 at 08:15:45PM -0500, Wenwen Wang wrote:
> >> >> In sctp_setsockopt_maxseg(), the integer 'val' is compared against min_len
> >> >> and max_len to check whether it is in the appropriate range. If it is not,
> >> >> an error code -EINVAL will be returned. This is enforced by a security
> >> >> check. But, this check is only executed when 'val' is not 0. In fact, if
> >> >> 'val' is 0, it will be assigned with a new value (if the return value of
> >> >> the function sctp_id2assoc() is not 0) in the following execution. However,
> >> >> this new value of 'val' is not checked before it is used to assigned to
> >> >> asoc->user_frag. That means it is possible that the new value of 'val'
> >> >> could be out of the expected range. This can cause security issues
> >> >> such as buffer overflows, e.g., the new value of 'val' is used as an index
> >> >> to access a buffer.
> >> >>
> >> >> This patch inserts a check for the new value of 'val' to see if it is in
> >> >> the expected range. If it is not, an error code -EINVAL will be returned.
> >> >>
> >> >> Signed-off-by: Wenwen Wang <[email protected]>
> >> >> ---
> >> >> net/sctp/socket.c | 22 +++++++++++-----------
> >> >> 1 file changed, 11 insertions(+), 11 deletions(-)
> >> >
> >> > ?
> >> > This patch is the same as previous one. git send-email <old file>
> >> > maybe?
> >> >
> >> > Marcelo
> >>
> >> Thanks for your suggestion, Marcelo. I can send the old file. But, I
> >> have added a line of comment in this patch.
> >
> > I meant if you had sent the old patch again by accident, because you
> > said you worked on an old version of the tree, but then posted a patch
> > that also doesn't use the new MTU function I mentioned.
> >
> > Marcelo
>
> I worked on the latest kernel. But, I didn't find the MTU function
> sctp_mtu_payload().
Which tree are you using?
[a] git://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git
or
[b] git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git
?
The function isn't on [a] yet, but it is on [b].
Marcelo
On Thu, May 3, 2018 at 7:46 AM, Marcelo Ricardo Leitner
<[email protected]> wrote:
> On Thu, May 03, 2018 at 07:01:51AM -0500, Wenwen Wang wrote:
>> On Wed, May 2, 2018 at 8:48 PM, Marcelo Ricardo Leitner
>> <[email protected]> wrote:
>> > On Wed, May 02, 2018 at 08:27:05PM -0500, Wenwen Wang wrote:
>> >> On Wed, May 2, 2018 at 8:24 PM, Marcelo Ricardo Leitner
>> >> <[email protected]> wrote:
>> >> > On Wed, May 02, 2018 at 08:15:45PM -0500, Wenwen Wang wrote:
>> >> >> In sctp_setsockopt_maxseg(), the integer 'val' is compared against min_len
>> >> >> and max_len to check whether it is in the appropriate range. If it is not,
>> >> >> an error code -EINVAL will be returned. This is enforced by a security
>> >> >> check. But, this check is only executed when 'val' is not 0. In fact, if
>> >> >> 'val' is 0, it will be assigned with a new value (if the return value of
>> >> >> the function sctp_id2assoc() is not 0) in the following execution. However,
>> >> >> this new value of 'val' is not checked before it is used to assigned to
>> >> >> asoc->user_frag. That means it is possible that the new value of 'val'
>> >> >> could be out of the expected range. This can cause security issues
>> >> >> such as buffer overflows, e.g., the new value of 'val' is used as an index
>> >> >> to access a buffer.
>> >> >>
>> >> >> This patch inserts a check for the new value of 'val' to see if it is in
>> >> >> the expected range. If it is not, an error code -EINVAL will be returned.
>> >> >>
>> >> >> Signed-off-by: Wenwen Wang <[email protected]>
>> >> >> ---
>> >> >> net/sctp/socket.c | 22 +++++++++++-----------
>> >> >> 1 file changed, 11 insertions(+), 11 deletions(-)
>> >> >
>> >> > ?
>> >> > This patch is the same as previous one. git send-email <old file>
>> >> > maybe?
>> >> >
>> >> > Marcelo
>> >>
>> >> Thanks for your suggestion, Marcelo. I can send the old file. But, I
>> >> have added a line of comment in this patch.
>> >
>> > I meant if you had sent the old patch again by accident, because you
>> > said you worked on an old version of the tree, but then posted a patch
>> > that also doesn't use the new MTU function I mentioned.
>> >
>> > Marcelo
>>
>> I worked on the latest kernel. But, I didn't find the MTU function
>> sctp_mtu_payload().
>
> Which tree are you using?
> [a] git://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git
> or
> [b] git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git
> ?
>
> The function isn't on [a] yet, but it is on [b].
>
> Marcelo
Many thanks for your patience, Marcelo :)
The tree I am working on is:
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Wenwen
On Thu, May 3, 2018 at 8:39 AM, Marcelo Ricardo Leitner
<[email protected]> wrote:
> On Thu, May 03, 2018 at 08:31:28AM -0500, Wenwen Wang wrote:
>> On Thu, May 3, 2018 at 7:46 AM, Marcelo Ricardo Leitner
>> <[email protected]> wrote:
>> > On Thu, May 03, 2018 at 07:01:51AM -0500, Wenwen Wang wrote:
>> >> On Wed, May 2, 2018 at 8:48 PM, Marcelo Ricardo Leitner
>> >> <[email protected]> wrote:
>> >> > On Wed, May 02, 2018 at 08:27:05PM -0500, Wenwen Wang wrote:
>> >> >> On Wed, May 2, 2018 at 8:24 PM, Marcelo Ricardo Leitner
>> >> >> <[email protected]> wrote:
>> >> >> > On Wed, May 02, 2018 at 08:15:45PM -0500, Wenwen Wang wrote:
>> >> >> >> In sctp_setsockopt_maxseg(), the integer 'val' is compared against min_len
>> >> >> >> and max_len to check whether it is in the appropriate range. If it is not,
>> >> >> >> an error code -EINVAL will be returned. This is enforced by a security
>> >> >> >> check. But, this check is only executed when 'val' is not 0. In fact, if
>> >> >> >> 'val' is 0, it will be assigned with a new value (if the return value of
>> >> >> >> the function sctp_id2assoc() is not 0) in the following execution. However,
>> >> >> >> this new value of 'val' is not checked before it is used to assigned to
>> >> >> >> asoc->user_frag. That means it is possible that the new value of 'val'
>> >> >> >> could be out of the expected range. This can cause security issues
>> >> >> >> such as buffer overflows, e.g., the new value of 'val' is used as an index
>> >> >> >> to access a buffer.
>> >> >> >>
>> >> >> >> This patch inserts a check for the new value of 'val' to see if it is in
>> >> >> >> the expected range. If it is not, an error code -EINVAL will be returned.
>> >> >> >>
>> >> >> >> Signed-off-by: Wenwen Wang <[email protected]>
>> >> >> >> ---
>> >> >> >> net/sctp/socket.c | 22 +++++++++++-----------
>> >> >> >> 1 file changed, 11 insertions(+), 11 deletions(-)
>> >> >> >
>> >> >> > ?
>> >> >> > This patch is the same as previous one. git send-email <old file>
>> >> >> > maybe?
>> >> >> >
>> >> >> > Marcelo
>> >> >>
>> >> >> Thanks for your suggestion, Marcelo. I can send the old file. But, I
>> >> >> have added a line of comment in this patch.
>> >> >
>> >> > I meant if you had sent the old patch again by accident, because you
>> >> > said you worked on an old version of the tree, but then posted a patch
>> >> > that also doesn't use the new MTU function I mentioned.
>> >> >
>> >> > Marcelo
>> >>
>> >> I worked on the latest kernel. But, I didn't find the MTU function
>> >> sctp_mtu_payload().
>> >
>> > Which tree are you using?
>> > [a] git://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git
>> > or
>> > [b] git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git
>> > ?
>> >
>> > The function isn't on [a] yet, but it is on [b].
>> >
>> > Marcelo
>>
>> Many thanks for your patience, Marcelo :)
>>
>> The tree I am working on is:
>> git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>
> Ahh! That explains the discrepancy :)
> For networking patches, please refer to
> Documentation/networking/netdev-FAQ.txt
> It describes what the 2 trees I pointed out are and how they should be
> used.
> In short, both net and net-next are always newer than the one you're
> using for networking subsystem.
>
> Regards,
> Marcelo
I see now. Will work on the new networking trees. Thanks!
Wenwen
On Thu, May 03, 2018 at 08:31:28AM -0500, Wenwen Wang wrote:
> On Thu, May 3, 2018 at 7:46 AM, Marcelo Ricardo Leitner
> <[email protected]> wrote:
> > On Thu, May 03, 2018 at 07:01:51AM -0500, Wenwen Wang wrote:
> >> On Wed, May 2, 2018 at 8:48 PM, Marcelo Ricardo Leitner
> >> <[email protected]> wrote:
> >> > On Wed, May 02, 2018 at 08:27:05PM -0500, Wenwen Wang wrote:
> >> >> On Wed, May 2, 2018 at 8:24 PM, Marcelo Ricardo Leitner
> >> >> <[email protected]> wrote:
> >> >> > On Wed, May 02, 2018 at 08:15:45PM -0500, Wenwen Wang wrote:
> >> >> >> In sctp_setsockopt_maxseg(), the integer 'val' is compared against min_len
> >> >> >> and max_len to check whether it is in the appropriate range. If it is not,
> >> >> >> an error code -EINVAL will be returned. This is enforced by a security
> >> >> >> check. But, this check is only executed when 'val' is not 0. In fact, if
> >> >> >> 'val' is 0, it will be assigned with a new value (if the return value of
> >> >> >> the function sctp_id2assoc() is not 0) in the following execution. However,
> >> >> >> this new value of 'val' is not checked before it is used to assigned to
> >> >> >> asoc->user_frag. That means it is possible that the new value of 'val'
> >> >> >> could be out of the expected range. This can cause security issues
> >> >> >> such as buffer overflows, e.g., the new value of 'val' is used as an index
> >> >> >> to access a buffer.
> >> >> >>
> >> >> >> This patch inserts a check for the new value of 'val' to see if it is in
> >> >> >> the expected range. If it is not, an error code -EINVAL will be returned.
> >> >> >>
> >> >> >> Signed-off-by: Wenwen Wang <[email protected]>
> >> >> >> ---
> >> >> >> net/sctp/socket.c | 22 +++++++++++-----------
> >> >> >> 1 file changed, 11 insertions(+), 11 deletions(-)
> >> >> >
> >> >> > ?
> >> >> > This patch is the same as previous one. git send-email <old file>
> >> >> > maybe?
> >> >> >
> >> >> > Marcelo
> >> >>
> >> >> Thanks for your suggestion, Marcelo. I can send the old file. But, I
> >> >> have added a line of comment in this patch.
> >> >
> >> > I meant if you had sent the old patch again by accident, because you
> >> > said you worked on an old version of the tree, but then posted a patch
> >> > that also doesn't use the new MTU function I mentioned.
> >> >
> >> > Marcelo
> >>
> >> I worked on the latest kernel. But, I didn't find the MTU function
> >> sctp_mtu_payload().
> >
> > Which tree are you using?
> > [a] git://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git
> > or
> > [b] git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git
> > ?
> >
> > The function isn't on [a] yet, but it is on [b].
> >
> > Marcelo
>
> Many thanks for your patience, Marcelo :)
>
> The tree I am working on is:
> git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Ahh! That explains the discrepancy :)
For networking patches, please refer to
Documentation/networking/netdev-FAQ.txt
It describes what the 2 trees I pointed out are and how they should be
used.
In short, both net and net-next are always newer than the one you're
using for networking subsystem.
Regards,
Marcelo