linux-kernel - [PATCH v2] block: register_blkdev doesn't check name against NULL

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Message-Id: <1378866250-22679-1-git-send-email-vaughan.cao@oracle.com>
Date:	Wed, 11 Sep 2013 10:24:10 +0800
From:	Vaughan Cao <vaughan.cao@...cle.com>
To:	axboe@...nel.dk, linux-kernel@...r.kernel.org
Cc:	vaughan.cao@...cle.com
Subject: [PATCH v2] block: register_blkdev doesn't check name against NULL

register_blkdev(0, NULL) can result kernel Oops by copying from NULL
in strlcpy(). Fix it by checking NULL pointer at the beginning and
WARN when encountered in unregister_blkdev.

Signed-off-by: Vaughan Cao <vaughan.cao@...cle.com>
---
 block/genhd.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/block/genhd.c b/block/genhd.c
index dadf42b..cca13e9 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -287,6 +287,9 @@ int register_blkdev(unsigned int major, const char *name)
 	struct blk_major_name **n, *p;
 	int index, ret = 0;
 
+	if (!name)
+		return -EINVAL;
+
 	mutex_lock(&block_class_lock);
 
 	/* temporary */
@@ -348,7 +351,7 @@ void unregister_blkdev(unsigned int major, const char *name)
 	for (n = &major_names[index]; *n; n = &(*n)->next)
 		if ((*n)->major == major)
 			break;
-	if (!*n || strcmp((*n)->name, name)) {
+	if (!*n || !name || strcmp((*n)->name, name)) {
 		WARN_ON(1);
 	} else {
 		p = *n;
-- 
1.8.3.1

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