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authorDavid Vrabel <david.vrabel@citrix.com>2014-09-02 15:21:30 +0100
committerDavid Vrabel <david.vrabel@citrix.com>2014-09-04 13:14:05 +0100
commit5903c6bd1a48d90b99e207ec2a6a7673cbbb732d (patch)
treef9e12fe0547957d77ca1c803da954999741794ae /drivers/xen
parente9de2e5fd602c4f5ddf212d3837b19ad4f5878ad (diff)
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xen/gntalloc: safely delete grefs in add_grefs() undo path
If a gref could not be added (perhaps because the limit has been reached or there are no more grant references available), the undo path may crash because __del_gref() frees the gref while it is being used for a list iteration. A comment suggests that using list_for_each_entry() is safe since the gref isn't removed from the list being iterated over, but it is freed and thus list_for_each_entry_safe() must be used. Also, explicitly delete the gref from the local per-file list, even though this is not strictly necessary. Signed-off-by: David Vrabel <david.vrabel@citrix.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Diffstat (limited to 'drivers/xen')
-rw-r--r--drivers/xen/gntalloc.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c
index 8ed2bb4f6f21..e53fe191738c 100644
--- a/drivers/xen/gntalloc.c
+++ b/drivers/xen/gntalloc.c
@@ -124,7 +124,7 @@ static int add_grefs(struct ioctl_gntalloc_alloc_gref *op,
int i, rc, readonly;
LIST_HEAD(queue_gref);
LIST_HEAD(queue_file);
- struct gntalloc_gref *gref;
+ struct gntalloc_gref *gref, *next;
readonly = !(op->flags & GNTALLOC_FLAG_WRITABLE);
rc = -ENOMEM;
@@ -160,8 +160,8 @@ undo:
mutex_lock(&gref_mutex);
gref_size -= (op->count - i);
- list_for_each_entry(gref, &queue_file, next_file) {
- /* __del_gref does not remove from queue_file */
+ list_for_each_entry_safe(gref, next, &queue_file, next_file) {
+ list_del(&gref->next_file);
__del_gref(gref);
}