1 files changed, 25 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index c3d653ba5ca0..b847745394b4 100644
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -757,6 +757,8 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
         si->is_empty = 0;
 
         if (!ec_corr) {
+                int image_seq;
+
                 /* Make sure UBI version is OK */
                 if (ech->version != UBI_VERSION) {
                         ubi_err("this UBI version is %d, image version is %d",
@@ -778,6 +780,29 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
                         ubi_dbg_dump_ec_hdr(ech);
                         return -EINVAL;
                 }
+
+                /*
+                 * Make sure that all PEBs have the same image sequence number.
+                 * This allows us to detect situations when users flash UBI
+                 * images incorrectly, so that the flash has the new UBI image
+                 * and leftovers from the old one. This feature was added
+                 * relatively recently, and the sequence number was always
+                 * zero, because old UBI implementations always set it to zero.
+                 * For this reasons, we do not panic if some PEBs have zero
+                 * sequence number, while other PEBs have non-zero sequence
+                 * number.
+                 */
+                image_seq = be32_to_cpu(ech->image_seq);
+                if (!si->image_seq_set) {
+                        ubi->image_seq = image_seq;
+                        si->image_seq_set = 1;
+                } else if (ubi->image_seq && ubi->image_seq != image_seq) {
+                        ubi_err("bad image sequence number %d in PEB %d, "
+                                "expected %d", image_seq, pnum, ubi->image_seq);
+                        ubi_dbg_dump_ec_hdr(ech);
+                        return -EINVAL;
+                }
+
         }
 
         /* OK, we've done with the EC header, let's look at the VID header */