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.carpen...@oracle.com>
Signed-off-by: Roger Pau Monné <roger....@citrix.com>
Cc: Konrad Rzeszutek Wilk <kon...@kernel.org>
Cc: xen-de...@lists.xen.org
---
drivers/block/xen-blkfront.c | 10 +++++++++-
1 files changed, 9 insertions(+), 1 deletions(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 96e9b00..df21b05 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -143,6 +143,13 @@ static DEFINE_SPINLOCK(minor_lock);
#define DEV_NAME "xvd" /* name in /dev */
+#define llist_for_each_entry_safe(pos, n, node, member) \
+ for ((pos) = llist_entry((node), typeof(*(pos)), member), \
+ (n) = (pos)->member.next; \
+ &(pos)->member != NULL; \
+ (pos) = llist_entry(n, typeof(*(pos)), member), \
+ (n) = (&(pos)->member != NULL) ? (pos)->member.next : NULL)
+
static int get_id_from_freelist(struct blkfront_info *info)
{
unsigned long free = info->shadow_free;
@@ -792,6 +799,7 @@ static void blkif_free(struct blkfront_info *info, int
suspend)
{
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 +812,7 @@ static void blkif_free(struct blkfront_info *info, int
suspend)
/* 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);
--
1.7.7.5 (Apple Git-26)
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