[PATCH] ceph: fix null pointer dereference

[PATCH] ceph: fix null pointer dereference

[Nathaniel Yazdani]

	When register_session() is given an out-of-range argument for mds,
ceph_mdsmap_get_addr() will return a null pointer, which would be given to
ceph_con_open() & be dereferenced, causing a kernel oops. This fixes bug #4685
in the Ceph bug tracker <http://tracker.ceph.com/issues/4685>.

Signed-off-by: Nathaniel Yazdani <n1ght.4nd.d4y@gmail.com>
---
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 187bf21..ddff072 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -414,6 +414,9 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
 {
 	struct ceph_mds_session *s;
 
+	if (mds >= mdsc->mdsmap->m_max_mds)
+		return ERR_PTR(-EINVAL);
+
 	s = kzalloc(sizeof(*s), GFP_NOFS);
 	if (!s)
 		return ERR_PTR(-ENOMEM);

Re: [PATCH] ceph: fix null pointer dereference

[Sage Weil]

Looks right, applied to the testing branch.

Thanks!
sage


On Sun, 4 Aug 2013, Nathaniel Yazdani wrote:

> 	When register_session() is given an out-of-range argument for mds,
> ceph_mdsmap_get_addr() will return a null pointer, which would be given to
> ceph_con_open() & be dereferenced, causing a kernel oops. This fixes bug #4685
> in the Ceph bug tracker <http://tracker.ceph.com/issues/4685>.
> 
> Signed-off-by: Nathaniel Yazdani <n1ght.4nd.d4y@gmail.com>
> ---
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 187bf21..ddff072 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -414,6 +414,9 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
>  {
>  	struct ceph_mds_session *s;
>  
> +	if (mds >= mdsc->mdsmap->m_max_mds)
> +		return ERR_PTR(-EINVAL);
> +
>  	s = kzalloc(sizeof(*s), GFP_NOFS);
>  	if (!s)
>  		return ERR_PTR(-ENOMEM);
> 
> 
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