ubi: ubi_create_volume: Fix use-after-free when volume creation failed

There is an use-after-free problem for 'eba_tbl' in ubi_create_volume()'s
error handling path:

  ubi_eba_replace_table(vol, eba_tbl)
    vol->eba_tbl = tbl
out_mapping:
  ubi_eba_destroy_table(eba_tbl)   // Free 'eba_tbl'
out_unlock:
  put_device(&vol->dev)
    vol_release
      kfree(tbl->entries)	  // UAF

Fix it by removing redundant 'eba_tbl' releasing.
Fetch a reproducer in [Link].

Fixes: 493cfaeaa0c9b ("mtd: utilize new cdev_device_add helper function")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215965
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
index 1bc7b3a..6ea95ad 100644 (file)
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -309,7 +309,6 @@ out_mapping:
        ubi->volumes[vol_id] = NULL;
        ubi->vol_count -= 1;
        spin_unlock(&ubi->volumes_lock);
-       ubi_eba_destroy_table(eba_tbl);
 out_acc:
        spin_lock(&ubi->volumes_lock);
        ubi->rsvd_pebs -= vol->reserved_pebs;