mtd: cfi_cmdset_0002: fix crash when erasing/writing AMD cards

Erasing an AMD linear flash card (AM29F016D) crashes after the first
sector has been erased. Likewise, writing to it crashes after two bytes
have been written. The reason is a missing check for a null pointer -
the cmdset_priv field is not set for this type of card.

Fixes: 4844ef80305d ("mtd: cfi_cmdset_0002: Add support for polling status register")
Signed-off-by: Andreas Persson <andreasp56@outlook.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/DB6P189MB05830B3530B8087476C5CFE4C1159@DB6P189MB0583.EURP189.PROD.OUTLOOK.COM

diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
index 3097e93787f72625dfc4a22888aec35c68141f1e..a761134fd3bea03432d4e846f01a196a13cbf8b6 100644 (file)
--- a/drivers/mtd/chips/cfi_cmdset_0002.c
+++ b/drivers/mtd/chips/cfi_cmdset_0002.c
@@ -119,7 +119,7 @@ static int cfi_use_status_reg(struct cfi_private *cfi)
        struct cfi_pri_amdstd *extp = cfi->cmdset_priv;
        u8 poll_mask = CFI_POLL_STATUS_REG | CFI_POLL_DQ;
 
-       return extp->MinorVersion >= '5' &&
+       return extp && extp->MinorVersion >= '5' &&
                (extp->SoftwareFeatures & poll_mask) == CFI_POLL_STATUS_REG;
 }