linux-kernel - [RFC PATCH v1 6/8] zram: avoid access beyond the zram device

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Date:	Mon,  3 Jun 2013 23:42:18 +0800
From:	Jiang Liu <liuj97@...il.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Nitin Gupta <ngupta@...are.org>,
	Minchan Kim <minchan@...nel.org>,
	Jerome Marchand <jmarchan@...hat.com>
Cc:	Yijing Wang <wangyijing@...wei.com>,
	Jiang Liu <jiang.liu@...wei.com>, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH v1 6/8] zram: avoid access beyond the zram device

Function valid_io_request() should verify the entire request doesn't
exceed the zram device, otherwise it will cause invalid memory access.

Signed-off-by: Jiang Liu <jiang.liu@...wei.com>
---
 drivers/staging/zram/zram_drv.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 66cf28a..64b51b9 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -428,6 +428,10 @@ static inline int valid_io_request(struct zram *zram, struct bio *bio)
 		return 0;
 	}
 
+	if (unlikely((bio->bi_sector << SECTOR_SHIFT) + bio->bi_size >=
+		     zram->disksize))
+		return 0;
+
 	/* I/O request is valid */
 	return 1;
 }
-- 
1.8.1.2

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