[MTD] Improve heuristic for detecting wrong-endian RedBoot partition table

Also limit the amount we scan to one eraseblock.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/mtd/redboot.c b/drivers/mtd/redboot.c
index a459ffa1e676..a61351f88ec0 100644
--- a/drivers/mtd/redboot.c
+++ b/drivers/mtd/redboot.c
@@ -94,7 +94,16 @@ static int parse_redboot_partitions(struct mtd_info *master,
                          * (NOTE: this is 'size' not 'data_length'; size is
                          * the full size of the entry.)
                          */
-                        if (swab32(buf[i].size) == master->erasesize) {
+
+                        /* RedBoot can combine the FIS directory and
+                           config partitions into a single eraseblock;
+                           we assume wrong-endian if either the swapped
+                           'size' matches the eraseblock size precisely,
+                           or if the swapped size actually fits in an
+                           eraseblock while the unswapped size doesn't. */
+                        if (swab32(buf[i].size) == master->erasesize ||
+                            (buf[i].size > master->erasesize
+                             && swab32(buf[i].size) < master->erasesize)) {
                                 int j;
                                 /* Update numslots based on actual FIS directory size */
                                 numslots = swab32(buf[i].size) / sizeof (struct fis_image_desc);
@@ -122,7 +131,7 @@ static int parse_redboot_partitions(struct mtd_info *master,
                                         swab32s(&buf[j].desc_cksum);
                                         swab32s(&buf[j].file_cksum);
                                 }
-                        } else {
+                        } else if (buf[i].size < master->erasesize) {
                                 /* Update numslots based on actual FIS directory size */
                                 numslots = buf[i].size / sizeof(struct fis_image_desc);
                         }