linux-kernel - [PATCH] UBI: block: Avoid disk size integer overflow

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Date:	Wed, 19 Mar 2014 15:57:54 +0100
From:	Richard Weinberger <richard@....at>
To:	dedekind1@...il.com
Cc:	ezequiel.garcia@...e-electrons.com, dwmw2@...radead.org,
	computersforpeace@...il.com, linux-mtd@...ts.infradead.org,
	linux-kernel@...r.kernel.org, Richard Weinberger <richard@....at>
Subject: [PATCH] UBI: block: Avoid disk size integer overflow

This patch fixes the issue that on very large UBI volumes
UBI block does not work correctly.

Signed-off-by: Richard Weinberger <richard@....at>
---
 drivers/mtd/ubi/block.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
index 9ef7df7..8887d4b 100644
--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -379,7 +379,7 @@ int ubiblock_create(struct ubi_volume_info *vi)
 {
 	struct ubiblock *dev;
 	struct gendisk *gd;
-	int disk_capacity;
+	u64 disk_capacity;
 	int ret;
 
 	/* Check that the volume isn't already handled */
@@ -413,7 +413,12 @@ int ubiblock_create(struct ubi_volume_info *vi)
 	gd->first_minor = dev->ubi_num * UBI_MAX_VOLUMES + dev->vol_id;
 	gd->private_data = dev;
 	sprintf(gd->disk_name, "ubiblock%d_%d", dev->ubi_num, dev->vol_id);
-	disk_capacity = (vi->size * vi->usable_leb_size) >> 9;
+	disk_capacity = ((u64)vi->size * vi->usable_leb_size) >> 9;
+	if ((sector_t)disk_capacity != disk_capacity) {
+		ubi_err("block: disk capacity %llu too large", disk_capacity);
+		ret = -E2BIG;
+		goto out_free_dev;
+	}
 	set_capacity(gd, disk_capacity);
 	dev->gd = gd;
 
@@ -500,7 +505,7 @@ int ubiblock_remove(struct ubi_volume_info *vi)
 static void ubiblock_resize(struct ubi_volume_info *vi)
 {
 	struct ubiblock *dev;
-	int disk_capacity;
+	u64 disk_capacity;
 
 	/*
 	 * Need to lock the device list until we stop using the device,
@@ -515,7 +520,13 @@ static void ubiblock_resize(struct ubi_volume_info *vi)
 	}
 
 	mutex_lock(&dev->dev_mutex);
-	disk_capacity = (vi->size * vi->usable_leb_size) >> 9;
+	disk_capacity = ((u64)vi->size * vi->usable_leb_size) >> 9;
+	if ((sector_t)disk_capacity != disk_capacity) {
+		ubi_err("block: disk capacity %llu too large", disk_capacity);
+		mutex_unlock(&dev->dev_mutex);
+		mutex_unlock(&devices_mutex);
+		return;
+	}
 	set_capacity(dev->gd, disk_capacity);
 	ubi_msg("%s resized to %d LEBs", dev->gd->disk_name, vi->size);
 	mutex_unlock(&dev->dev_mutex);
-- 
1.8.1.4

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