linux-kernel - [PATCH resend 3/5] libata-scsi: fix overflow in mode page copy

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Date:	Fri, 22 Jul 2016 02:41:52 +0800
From:	tom.ty89@...il.com
To:	tj@...nel.org, hare@...e.de, sergei.shtylyov@...entembedded.com,
	arnd@...db.de
Cc:	sfr@...b.auug.org.au, linux-ide@...r.kernel.org,
	linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-next@...r.kernel.org, Tom Yan <tom.ty89@...il.com>
Subject: [PATCH resend 3/5] libata-scsi: fix overflow in mode page copy

From: Tom Yan <tom.ty89@...il.com>

ata_mselect_*() would initialize a char array for storing a copy of
the current mode page. However, if char was actually signed char,
overflow could occur.

For example, `0xff` from def_control_mpage[] would be "truncated"
to `-1`. This prevented ata_mselect_control() from working at all,
since when it did the read-only bits check, there would always be
a mismatch.

Signed-off-by: Tom Yan <tom.ty89@...il.com>

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index ac90676..3c93341 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3610,7 +3610,7 @@ static int ata_mselect_caching(struct ata_queued_cmd *qc,
 {
 	struct ata_taskfile *tf = &qc->tf;
 	struct ata_device *dev = qc->dev;
-	char mpage[CACHE_MPAGE_LEN];
+	u8 mpage[CACHE_MPAGE_LEN];
 	u8 wce;
 	int i;
 
@@ -3675,7 +3675,7 @@ static int ata_mselect_control(struct ata_queued_cmd *qc,
 			       const u8 *buf, int len, u16 *fp)
 {
 	struct ata_device *dev = qc->dev;
-	char mpage[CONTROL_MPAGE_LEN];
+	u8 mpage[CONTROL_MPAGE_LEN];
 	u8 d_sense;
 	int i;
 
-- 
2.9.0