mtd: nand: fix pointer NULL pointer dereferencing

In 'verify_bbt_descr()', first check the "bd" pointer, then
dereference it.

Comments amended by Artem.

Signed-off-by: Stanislav Fomichev <kernel@fomichev.me>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
index 6ebd869993aa..a1e8b30078d9 100644
--- a/drivers/mtd/nand/nand_bbt.c
+++ b/drivers/mtd/nand/nand_bbt.c
@@ -1101,12 +1101,16 @@ static void mark_bbt_region(struct mtd_info *mtd, struct nand_bbt_descr *td)
 static void verify_bbt_descr(struct mtd_info *mtd, struct nand_bbt_descr *bd)
 {
         struct nand_chip *this = mtd->priv;
-        u32 pattern_len = bd->len;
-        u32 bits = bd->options & NAND_BBT_NRBITS_MSK;
+        u32 pattern_len;
+        u32 bits;
         u32 table_size;
 
         if (!bd)
                 return;
+
+        pattern_len = bd->len;
+        bits = bd->options & NAND_BBT_NRBITS_MSK;
+
         BUG_ON((this->options & NAND_USE_FLASH_BBT_NO_OOB) &&
                         !(this->options & NAND_USE_FLASH_BBT));
         BUG_ON(!bits);