mtd: cmdlinepart: make the partitions rule more strict

Huang Shijie <shijie8@gmail.com> explains:

Assume we have a 1GiB(8Gib) NAND chip, and we set the partitions
in the command line like this:
    #gpmi-nand:100m(boot),100m(kernel),1g(rootfs)

In this case, the partition truncating occurs. The current code will
get the following result:

     ----------------------------------
        root@freescale ~$ cat /proc/mtd
        dev:    size   erasesize  name
        mtd0: 06400000 00040000 "boot"
        mtd1: 06400000 00040000 "kernel"
     ----------------------------------

It is obvious that we lost the truncated partition `rootfs` which should
be 824MiB in this case.

Also, forbid 0-sized partitions.

Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/drivers/mtd/cmdlinepart.c b/drivers/mtd/cmdlinepart.c
index 17b0bd463839..aed1b8a63c9f 100644
--- a/drivers/mtd/cmdlinepart.c
+++ b/drivers/mtd/cmdlinepart.c
@@ -319,12 +319,22 @@ static int parse_cmdline_partitions(struct mtd_info *master,
                                 if (part->parts[i].size == SIZE_REMAINING)
                                         part->parts[i].size = master->size - offset;
 
+                                if (part->parts[i].size == 0) {
+                                        printk(KERN_WARNING ERRP
+                                               "%s: skipping zero sized partition\n",
+                                               part->mtd_id);
+                                        part->num_parts--;
+                                        memmove(&part->parts[i],
+                                                &part->parts[i + 1],
+                                                sizeof(*part->parts) * (part->num_parts - i));
+                                        continue;
+                                }
+
                                 if (offset + part->parts[i].size > master->size) {
                                         printk(KERN_WARNING ERRP
                                                "%s: partitioning exceeds flash size, truncating\n",
                                                part->mtd_id);
                                         part->parts[i].size = master->size - offset;
-                                        part->num_parts = i;
                                 }
                                 offset += part->parts[i].size;
                         }