mtd: bcm63xxpart: check the image tag's crc32

Only use the values from the image tag if it is valid. Always create
the CFE, NVRAM and linux partitions, to allow flashing a new image even
if the old is invalid without overwriting CFE or NVRAM.

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 29 insertions, 16 deletions

diff --git a/drivers/mtd/bcm63xxpart.c b/drivers/mtd/bcm63xxpart.c
index 6afc4aa3c622..9ee8bc426e93 100644
--- a/drivers/mtd/bcm63xxpart.c
+++ b/drivers/mtd/bcm63xxpart.c
@@ -24,6 +24,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/crc32.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
@@ -80,8 +81,7 @@ static int bcm63xx_parse_cfe_partitions(struct mtd_info *master,
         unsigned int cfelen, nvramlen;
         int namelen = 0;
         int i;
-        char *boardid;
-        char *tagversion;
+        u32 computed_crc;
 
         if (bcm63xx_detect_cfe(master))
                 return -EINVAL;
@@ -103,20 +103,33 @@ static int bcm63xx_parse_cfe_partitions(struct mtd_info *master,
                 return -EIO;
         }
 
-        sscanf(buf->kernel_address, "%u", &kerneladdr);
-        sscanf(buf->kernel_length, "%u", &kernellen);
-        sscanf(buf->total_length, "%u", &totallen);
-        tagversion = &(buf->tag_version[0]);
-        boardid = &(buf->board_id[0]);
-
-        pr_info("CFE boot tag found with version %s and board type %s\n",
-                tagversion, boardid);
-
-        kerneladdr = kerneladdr - BCM63XX_EXTENDED_SIZE;
-        rootfsaddr = kerneladdr + kernellen;
-        spareaddr = roundup(totallen, master->erasesize) + cfelen;
-        sparelen = master->size - spareaddr - nvramlen;
-        rootfslen = spareaddr - rootfsaddr;
+        computed_crc = crc32_le(IMAGETAG_CRC_START, (u8 *)buf,
+                                offsetof(struct bcm_tag, header_crc));
+        if (computed_crc == buf->header_crc) {
+                char *boardid = &(buf->board_id[0]);
+                char *tagversion = &(buf->tag_version[0]);
+
+                sscanf(buf->kernel_address, "%u", &kerneladdr);
+                sscanf(buf->kernel_length, "%u", &kernellen);
+                sscanf(buf->total_length, "%u", &totallen);
+
+                pr_info("CFE boot tag found with version %s and board type %s\n",
+                        tagversion, boardid);
+
+                kerneladdr = kerneladdr - BCM63XX_EXTENDED_SIZE;
+                rootfsaddr = kerneladdr + kernellen;
+                spareaddr = roundup(totallen, master->erasesize) + cfelen;
+                sparelen = master->size - spareaddr - nvramlen;
+                rootfslen = spareaddr - rootfsaddr;
+        } else {
+                pr_warn("CFE boot tag CRC invalid (expected %08x, actual %08x)\n",
+                        buf->header_crc, computed_crc);
+                kernellen = 0;
+                rootfslen = 0;
+                rootfsaddr = 0;
+                spareaddr = cfelen;
+                sparelen = master->size - cfelen - nvramlen;
+        }
 
         /* Determine number of partitions */
         namelen = 8;