linux-kernel - [PATCH] ata: Eliminate usage of uninitialized

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Message-ID: <20200615040236.3720734-1-yanaijie@huawei.com>
Date:   Mon, 15 Jun 2020 12:02:36 +0800
From:   Jason Yan <yanaijie@...wei.com>
To:     <axboe@...nel.dk>, <b.zolnierkie@...sung.com>,
        <linux-ide@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <kernel-hardening@...ts.openwall.com>,
        Jason Yan <yanaijie@...wei.com>,
        Kees Cook <keescook@...omium.org>
Subject: [PATCH] ata: Eliminate usage of uninitialized_var() macro

This is an effort to eliminate the uninitialized_var() macro[1].

The use of this macro is the wrong solution because it forces off ANY
analysis by the compiler for a given variable. It even masks "unused
variable" warnings.

Quoted from Linus[2]:

"It's a horrible thing to use, in that it adds extra cruft to the
source code, and then shuts up a compiler warning (even the _reliable_
warnings from gcc)."

The gcc option "-Wmaybe-uninitialized" has been disabled and this change
will not produce any warnnings even with "make W=1".

[1] https://github.com/KSPP/linux/issues/81
[2] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/

Cc: Kees Cook <keescook@...omium.org>
Signed-off-by: Jason Yan <yanaijie@...wei.com>
---
 drivers/ata/libata-scsi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 435781a16875..fcb00f2825fe 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -93,7 +93,7 @@ static ssize_t ata_scsi_park_show(struct device *device,
 	struct ata_link *link;
 	struct ata_device *dev;
 	unsigned long now;
-	unsigned int uninitialized_var(msecs);
+	unsigned int msecs;
 	int rc = 0;
 
 	ap = ata_shost_to_port(sdev->host);
-- 
2.25.4