linux-kernel - [PATCH] scsi: advansys: fix uninitialized data access

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Date:   Thu, 23 Mar 2017 16:02:18 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Matthew Wilcox <mawilcox@...rosoft.com>,
        Hannes Reinecke <hare@...e.com>,
        "James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     Arnd Bergmann <arnd@...db.de>, linux-scsi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] scsi: advansys: fix uninitialized data access

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

diff --git a/drivers/scsi/advansys.c b/drivers/scsi/advansys.c
index 81dd0927246b..24e57e770432 100644
--- a/drivers/scsi/advansys.c
+++ b/drivers/scsi/advansys.c
@@ -6291,18 +6291,17 @@ static uchar AscGetSynPeriodIndex(ASC_DVC_VAR *asc_dvc, uchar syn_time)
 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,
-- 
2.9.0