[patch 17/37] md: avoid dereferencing NULL pointer when accessing suspend_* sysfs attributes.

[Greg KH]

2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------

From: NeilBrown <neilb@xxxxxxx>

commit b8d966efd9a46a9a35beac50cbff6e30565125ef upstream.

If we try to modify one of the md/ sysfs files
  suspend_lo or suspend_hi
when the array is not active, we dereference a NULL.
Protect against that.

Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/md/md.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -3281,7 +3281,8 @@ suspend_lo_store(mddev_t *mddev, const c
 	char *e;
 	unsigned long long new = simple_strtoull(buf, &e, 10);
 
-	if (mddev->pers->quiesce == NULL)
+	if (mddev->pers == NULL ||
+	    mddev->pers->quiesce == NULL)
 		return -EINVAL;
 	if (buf == e || (*e && *e != '\n'))
 		return -EINVAL;
@@ -3309,7 +3310,8 @@ suspend_hi_store(mddev_t *mddev, const c
 	char *e;
 	unsigned long long new = simple_strtoull(buf, &e, 10);
 
-	if (mddev->pers->quiesce == NULL)
+	if (mddev->pers == NULL ||
+	    mddev->pers->quiesce == NULL)
 		return -EINVAL;
 	if (buf == e || (*e && *e != '\n'))
 		return -EINVAL;


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