The patch below does not apply to the 3.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 144f4c98399e2c0ca60eb414c15a2c68125c18b8 Mon Sep 17 00:00:00 2001
From: Hector Palacios <hector.palacios@xxxxxxxx>
Date: Mon, 18 Jul 2016 10:39:18 +0200
Subject: [PATCH] mtd: nand: fix bug writing 1 byte less than page size
nand_do_write_ops() determines if it is writing a partial page with the
formula:
part_pagewr = (column || writelen < (mtd->writesize - 1))
When 'writelen' is exactly 1 byte less than the NAND page size the formula
equates to zero, so the code doesn't process it as a partial write,
although it should.
As a consequence the function remains in the while(1) loop with 'writelen'
becoming 0xffffffff and iterating endlessly.
The bug may not be easy to reproduce in Linux since user space tools
usually force the padding or round-up the write size to a page-size
multiple.
This was discovered in U-Boot where the issue can be reproduced by
writing any size that is 1 byte less than a page-size multiple.
For example, on a NAND with 2K page (0x800):
=> nand erase.part <partition>
=> nand write $loadaddr <partition> 7ff
[Editor's note: the bug was added in commit 29072b96078f, but moved
around in commit 66507c7bc8895 ("mtd: nand: Add support to use nand_base
poi databuf as bounce buffer")]
Fixes: 29072b96078f ("[MTD] NAND: add subpage write support")
Signed-off-by: Hector Palacios <hector.palacios@xxxxxxxx>
Acked-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Brian Norris <computersforpeace@xxxxxxxxx>
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 0b0dc29d2af7..77533f7f2429 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2610,7 +2610,7 @@ static int nand_do_write_ops(struct mtd_info *mtd, loff_t to,
int cached = writelen > bytes && page != blockmask;
uint8_t *wbuf = buf;
int use_bufpoi;
- int part_pagewr = (column || writelen < (mtd->writesize - 1));
+ int part_pagewr = (column || writelen < mtd->writesize);
if (part_pagewr)
use_bufpoi = 1;
--
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