netdev - Re: [PATCH] sctp: fix a potential missing-check bug

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Date:   Wed, 2 May 2018 22:48:38 -0300
From:   Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:     Wenwen Wang <wang6495@....edu>
Cc:     Kangjie Lu <kjlu@....edu>, Vlad Yasevich <vyasevich@...il.com>,
        Neil Horman <nhorman@...driver.com>,
        "David S. Miller" <davem@...emloft.net>,
        "open list:SCTP PROTOCOL" <linux-sctp@...r.kernel.org>,
        "open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] sctp: fix a potential missing-check bug

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
> <marcelo.leitner@...il.com> 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 <wang6495@....edu>
> >> ---
> >>  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