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From: "Darrick J. Wong" <>
To: Douglas Gilbert <>,
	James Bottomley <>
Cc: linux-scsi <>,
	linux-kernel <>
Subject: [PATCH] scsi_debug: Fix 32-bit overflow in do_device_access
Date: Mon, 31 Jan 2011 18:47:54 -0800	[thread overview]
Message-ID: <> (raw)

If I create a scsi_debug device that is larger than 4GB, the multiplication of
(block * scsi_debug_sector_size) can produce a 64-bit value.  Unfortunately,
the compiler sees two 32-bit quantities and performs a 32-bit multiplication,
thus truncating the bits above 2^32.  This causes the wrong memory location to
be read or written.  Change block and rest to be unsigned long long.

Signed-off-by: Darrick J. Wong <>

 drivers/scsi/scsi_debug.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 7b31093..a6b2d72 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -1671,7 +1671,7 @@ static int do_device_access(struct scsi_cmnd *scmd,
 			    unsigned long long lba, unsigned int num, int write)
 	int ret;
-	unsigned int block, rest = 0;
+	unsigned long long block, rest = 0;
 	int (*func)(struct scsi_cmnd *, unsigned char *, int);
 	func = write ? fetch_to_dev_buffer : fill_from_dev_buffer;

             reply	other threads:[~2011-02-01  2:47 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-01  2:47 Darrick J. Wong [this message]
2011-02-03 18:53 ` Douglas Gilbert

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