[PATCH 5.10 015/306] ceph: fix dereference of null pointer cf

[Greg Kroah-Hartman]

From: Colin Ian King <colin.king@xxxxxxxxxxxxx>

commit 05a444d3f90a3c3e6362e88a1bf13e1a60f8cace upstream.

Currently in the case where kmem_cache_alloc fails the null pointer
cf is dereferenced when assigning cf->is_capsnap = false. Fix this
by adding a null pointer check and return path.

Cc: stable@xxxxxxxxxxxxxxx
Addresses-Coverity: ("Dereference null return")
Fixes: b2f9fa1f3bd8 ("ceph: correctly handle releasing an embedded cap flush")
Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
Reviewed-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/ceph/caps.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -1755,6 +1755,9 @@ struct ceph_cap_flush *ceph_alloc_cap_fl
 	struct ceph_cap_flush *cf;
 
 	cf = kmem_cache_alloc(ceph_cap_flush_cachep, GFP_KERNEL);
+	if (!cf)
+		return NULL;
+
 	cf->is_capsnap = false;
 	return cf;
 }