linux-kernel - [ 14/19] block: avoid using uninitialized value in from queue_var

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Message-Id: <20130410225028.288909114@linuxfoundation.org>
Date:	Wed, 10 Apr 2013 15:50:37 -0700
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>,
	Jens Axboe <axboe@...nel.dk>
Subject: [ 14/19] block: avoid using uninitialized value in from queue_var_store

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

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

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

commit c678ef5286ddb5cf70384ad5af286b0afc9b73e1 upstream.

As found by gcc-4.8, the QUEUE_SYSFS_BIT_FNS macro creates functions
that use a value generated by queue_var_store independent of whether
that value was set or not.

block/blk-sysfs.c: In function 'queue_store_nonrot':
block/blk-sysfs.c:244:385: warning: 'val' may be used uninitialized in this function [-Wmaybe-uninitialized]

Unlike most other such warnings, this one is not a false positive,
writing any non-number string into the sysfs files indeed has
an undefined result, rather than returning an error.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 block/blk-sysfs.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -200,6 +200,8 @@ queue_store_##name(struct request_queue
 	unsigned long val;						\
 	ssize_t ret;							\
 	ret = queue_var_store(&val, page, count);			\
+	if (ret < 0)							\
+		 return ret;						\
 	if (neg)							\
 		val = !val;						\
 									\


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