mtd: nand: check ecc->total sanity in nand_scan_tail

Message ID 1495687820-30692-1-git-send-email-yamada.masahiro@socionext.com
State Accepted
Commit 79e0348c4e24fd1affdcf055e0269755580e0fcc
Headers show

Commit Message

Masahiro Yamada May 25, 2017, 4:50 a.m.
Drivers are supposed to set correct ecc->{size,strength,bytes} before
calling nand_scan_tail(), but it does not complain about ecc->total
bigger than oobsize.

In this case, chip->scan_bbt() crashes due to memory corruption, but
it is hard to debug.  It would be kind to fail it earlier with a clear
message.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

---

I was actually hit by this case.

I wasted half a day until I figured out my coding mistake in my
Denali driver.  It will be helpful to check this in NAND core.


 drivers/mtd/nand/nand_base.c | 5 +++++
 1 file changed, 5 insertions(+)

-- 
2.7.4


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diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index f4d686192717..14d6a5aa3ee8 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -4970,6 +4970,11 @@  int nand_scan_tail(struct mtd_info *mtd)
 		goto err_free;
 	}
 	ecc->total = ecc->steps * ecc->bytes;
+	if (ecc->total > mtd->oobsize) {
+		WARN(1, "Total number of ECC bytes exceeded oobsize\n");
+		ret = -EINVAL;
+		goto err_free;
+	}
 
 	/*
 	 * The number of bytes available for a client to place data into