llist/xen-blkfront: implement safe version of llist_for_each_entry
Implement a safe version of llist_for_each_entry, and use it in
blkif_free. Previously grants where freed while iterating the list,
which lead to dereferences when trying to fetch the next item.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
[v2: Move the llist_for_each_entry_safe in llist.h]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 96e9b00..cfdb033 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -792,6 +792,7 @@
{
struct llist_node *all_gnts;
struct grant *persistent_gnt;
+ struct llist_node *n;
/* Prevent new requests being issued until we fix things up. */
spin_lock_irq(&info->io_lock);
@@ -804,7 +805,7 @@
/* Remove all persistent grants */
if (info->persistent_gnts_c) {
all_gnts = llist_del_all(&info->persistent_gnts);
- llist_for_each_entry(persistent_gnt, all_gnts, node) {
+ llist_for_each_entry_safe(persistent_gnt, n, all_gnts, node) {
gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
__free_page(pfn_to_page(persistent_gnt->pfn));
kfree(persistent_gnt);