linux-kernel - [PATCH 4.4 077/193] scsi: advansys: fix uninitialized data access

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Date:   Fri, 23 Feb 2018 19:25:10 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Subject: [PATCH 4.4 077/193] scsi: advansys: fix uninitialized data access

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arnd Bergmann <arnd@...db.de>

commit 44a5b977128c0ffff0654392b40f4c2ce72a619b upstream.

gcc-7.0.1 now warns about a previously unnoticed access of uninitialized
struct members:

drivers/scsi/advansys.c: In function 'AscMsgOutSDTR':
drivers/scsi/advansys.c:3860:26: error: '*((void *)&sdtr_buf+5)' may be used uninitialized in this function [-Werror=maybe-uninitialized]
         ((ushort)s_buffer[i + 1] << 8) | s_buffer[i]);
                          ^
drivers/scsi/advansys.c:3860:26: error: '*((void *)&sdtr_buf+7)' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/scsi/advansys.c:3860:26: error: '*((void *)&sdtr_buf+5)' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/scsi/advansys.c:3860:26: error: '*((void *)&sdtr_buf+7)' may be used uninitialized in this function [-Werror=maybe-uninitialized]

The code has existed in this exact form at least since v2.6.12, and the
warning seems correct. This uses named initializers to ensure we
initialize all members of the structure.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/scsi/advansys.c |   21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

--- a/drivers/scsi/advansys.c
+++ b/drivers/scsi/advansys.c
@@ -6291,18 +6291,17 @@ static uchar AscGetSynPeriodIndex(ASC_DV
 static uchar
 AscMsgOutSDTR(ASC_DVC_VAR *asc_dvc, uchar sdtr_period, uchar sdtr_offset)
 {
-	EXT_MSG sdtr_buf;
-	uchar sdtr_period_index;
-	PortAddr iop_base;
-
-	iop_base = asc_dvc->iop_base;
-	sdtr_buf.msg_type = EXTENDED_MESSAGE;
-	sdtr_buf.msg_len = MS_SDTR_LEN;
-	sdtr_buf.msg_req = EXTENDED_SDTR;
-	sdtr_buf.xfer_period = sdtr_period;
+	PortAddr iop_base = asc_dvc->iop_base;
+	uchar sdtr_period_index = AscGetSynPeriodIndex(asc_dvc, sdtr_period);
+	EXT_MSG sdtr_buf = {
+		.msg_type = EXTENDED_MESSAGE,
+		.msg_len = MS_SDTR_LEN,
+		.msg_req = EXTENDED_SDTR,
+		.xfer_period = sdtr_period,
+		.req_ack_offset = sdtr_offset,
+	};
 	sdtr_offset &= ASC_SYN_MAX_OFFSET;
-	sdtr_buf.req_ack_offset = sdtr_offset;
-	sdtr_period_index = AscGetSynPeriodIndex(asc_dvc, sdtr_period);
+
 	if (sdtr_period_index <= asc_dvc->max_sdtr_index) {
 		AscMemWordCopyPtrToLram(iop_base, ASCV_MSGOUT_BEG,
 					(uchar *)&sdtr_buf,