[patch -next] libceph: fix NULL dereference in reset_connection()

[patch -next] libceph: fix NULL dereference in reset_connection()

[Dan Carpenter]

We dereference "con->in_msg" on the line after it was set to NULL.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 5e9f61d..6aa671c 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -437,10 +437,10 @@ static void reset_connection(struct ceph_connection *con)
 
 	if (con->in_msg) {
 		BUG_ON(con->in_msg->con != con);
+		ceph_con_put(con->in_msg->con);
 		con->in_msg->con = NULL;
 		ceph_msg_put(con->in_msg);
 		con->in_msg = NULL;
-		ceph_con_put(con->in_msg->con);
 	}
 
 	con->connect_seq = 0;

Re: [patch -next] libceph: fix NULL dereference in reset_connection()

[Alex Elder]

On 06/19/2012 05:33 AM, Dan Carpenter wrote:
> We dereference "con->in_msg" on the line after it was set to NULL.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Yikes.

Actually I think I prefer a different fix, which is
simply to call ceph_con_put(con) in the same spot
it was called with con->in_msg->con before.  I'd
rather drop the message reference before dropping
the connection reference.  I.e.:

@@ -440,7 +440,7 @@ static void reset_connection(struct ceph_connection
*con)
 		con->in_msg->con = NULL;
 		ceph_msg_put(con->in_msg);
 		con->in_msg = NULL;
-		ceph_con_put(con->in_msg->con);
+		ceph_con_put(con);
 	}

 	con->connect_seq = 0;

(I crafted that manually--it may not work...)

I will re-post that fix and will credit you with it.  Please acknowledge
it's OK with you though.  Thanks a lot.

					-Alex

> diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
> index 5e9f61d..6aa671c 100644
> --- a/net/ceph/messenger.c
> +++ b/net/ceph/messenger.c
> @@ -437,10 +437,10 @@ static void reset_connection(struct ceph_connection *con)
>  
>  	if (con->in_msg) {
>  		BUG_ON(con->in_msg->con != con);
> +		ceph_con_put(con->in_msg->con);
>  		con->in_msg->con = NULL;
>  		ceph_msg_put(con->in_msg);
>  		con->in_msg = NULL;
> -		ceph_con_put(con->in_msg->con);
>  	}
>  
>  	con->connect_seq = 0;
> 

Re: [patch -next] libceph: fix NULL dereference in reset_connection()

[Dan Carpenter]

On Tue, Jun 19, 2012 at 08:27:19AM -0500, Alex Elder wrote:
> On 06/19/2012 05:33 AM, Dan Carpenter wrote:
> > We dereference "con->in_msg" on the line after it was set to NULL.
> > 
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> Yikes.
> 
> Actually I think I prefer a different fix, which is
> simply to call ceph_con_put(con) in the same spot
> it was called with con->in_msg->con before.  I'd
> rather drop the message reference before dropping
> the connection reference.  I.e.:
> 
> @@ -440,7 +440,7 @@ static void reset_connection(struct ceph_connection
> *con)
>  		con->in_msg->con = NULL;
>  		ceph_msg_put(con->in_msg);
>  		con->in_msg = NULL;
> -		ceph_con_put(con->in_msg->con);
> +		ceph_con_put(con);
>  	}
> 
>  	con->connect_seq = 0;
> 
> (I crafted that manually--it may not work...)
> 
> I will re-post that fix and will credit you with it.  Please acknowledge
> it's OK with you though.  Thanks a lot.
> 

Yep.  We already know that con->in_msg->con and con are the same
from the BUG_ON() so this works.  Thanks.

regards,
dan carpenter

[PATCH] libceph: fix NULL dereference in reset_connection()

[Alex Elder]

I have already incorporated the following in the Ceph master
branch (which is used for the -next build).  We will also send
this to Linus soon.

					-Alex
====
We dereference "con->in_msg" on the line after it was set to NULL.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Alex Elder <elder@inktank.com>
---
 net/ceph/messenger.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 5e9f61d..23073cf 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -440,7 +440,7 @@ static void reset_connection(struct ceph_connection
*con)
 		con->in_msg->con = NULL;
 		ceph_msg_put(con->in_msg);
 		con->in_msg = NULL;
-		ceph_con_put(con->in_msg->con);
+		ceph_con_put(con);
 	}

 	con->connect_seq = 0;