Re: [PATCH] ubi: gluebi_{read,write} len + {from,to} can exceed mtd->size

Re: [PATCH] ubi: gluebi_{read,write} len + {from,to} can exceed mtd->size

[Artem Bityutskiy]

On Mon, 2009-06-22 at 19:21 +0200, Roel Kluin wrote:
> when size_t `len' is negative it is wrapped so the test `len < 0' fails.
> `from' and `to' have type loff_t (signed). During the addition `len' is
> converted to signed. So when `len' is negative `from + len` can be
> less than `mtd->size' while `from' is larger than `mtd->size'. This
> patch fixes this.
> 
> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>

Thanks, pushed to ubi-2.6.git tree with slightly amended commit message:

commit cf9e1e425172035575bee070df031c8a58015cb8
Author: Roel Kluin <roel.kluin@gmail.com>
Date:   Mon Jun 22 19:21:38 2009 +0200

    UBI: fix input parameters check in gluebi

    size_t `len' is unsigned `len < 0' always fails.
    `from' and `to' have type loff_t (signed). During the addition `len' is
    converted to signed. So when `len' is negative `from + len` can be
    less than `mtd->size' while `from' is larger than `mtd->size'. This
    patch fixes this.

    Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
    Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)

[PATCH] ubi: gluebi_{read, write} len + {from, to} can exceed mtd->size

[Roel Kluin]

when size_t `len' is negative it is wrapped so the test `len < 0' fails.
`from' and `to' have type loff_t (signed). During the addition `len' is
converted to signed. So when `len' is negative `from + len` can be
less than `mtd->size' while `from' is larger than `mtd->size'. This
patch fixes this.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
---
It should be correct, but please review.

diff --git a/drivers/mtd/ubi/gluebi.c b/drivers/mtd/ubi/gluebi.c
index 95aaac0..093729b 100644
--- a/drivers/mtd/ubi/gluebi.c
+++ b/drivers/mtd/ubi/gluebi.c
@@ -173,7 +173,7 @@ static int gluebi_read(struct mtd_info *mtd, loff_t from, size_t len,
 	int err = 0, lnum, offs, total_read;
 	struct gluebi_device *gluebi;
 
-	if (len < 0 || from < 0 || from + len > mtd->size)
+	if (len > mtd->size || from < 0 || from + len > mtd->size)
 		return -EINVAL;
 
 	gluebi = container_of(mtd, struct gluebi_device, mtd);
@@ -217,7 +217,7 @@ static int gluebi_write(struct mtd_info *mtd, loff_t to, size_t len,
 	int err = 0, lnum, offs, total_written;
 	struct gluebi_device *gluebi;
 
-	if (len < 0 || to < 0 || len + to > mtd->size)
+	if (len > mtd->size || to < 0 || len + to > mtd->size)
 		return -EINVAL;
 
 	gluebi = container_of(mtd, struct gluebi_device, mtd);