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-rw-r--r--block/genhd.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/block/genhd.c b/block/genhd.c
index 1d0d25f7b0fe..83f5c33d1e80 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -531,6 +531,18 @@ void blk_free_devt(dev_t devt)
}
}
+/**
+ * We invalidate devt by assigning NULL pointer for devt in idr.
+ */
+void blk_invalidate_devt(dev_t devt)
+{
+ if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
+ spin_lock_bh(&ext_devt_lock);
+ idr_replace(&ext_devt_idr, NULL, blk_mangle_minor(MINOR(devt)));
+ spin_unlock_bh(&ext_devt_lock);
+ }
+}
+
static char *bdevt_str(dev_t devt, char *buf)
{
if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {
@@ -793,6 +805,13 @@ void del_gendisk(struct gendisk *disk)
if (!(disk->flags & GENHD_FL_HIDDEN))
blk_unregister_region(disk_devt(disk), disk->minors);
+ /*
+ * Remove gendisk pointer from idr so that it cannot be looked up
+ * while RCU period before freeing gendisk is running to prevent
+ * use-after-free issues. Note that the device number stays
+ * "in-use" until we really free the gendisk.
+ */
+ blk_invalidate_devt(disk_devt(disk));
kobject_put(disk->part0.holder_dir);
kobject_put(disk->slave_dir);