linux-kernel - [patch v2] libertas: potential oops in debugfs

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Date:	Wed, 30 Oct 2013 20:12:51 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	"John W. Linville" <linville@...driver.com>
Cc:	libertas-dev@...ts.infradead.org, linux-wireless@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [patch v2] libertas: potential oops in debugfs

If we do a zero size allocation then it will oops.  Also we can't be
sure the user passes us a NUL terminated string so I've added a
terminator.

This code can only be triggered by root.

Reported-by: Nico Golde <nico@...lde.de>
Reported-by: Fabian Yamaguchi <fabs@...sec.de>
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>

diff --git a/drivers/net/wireless/libertas/debugfs.c b/drivers/net/wireless/libertas/debugfs.c
index 668dd27..1917348 100644
--- a/drivers/net/wireless/libertas/debugfs.c
+++ b/drivers/net/wireless/libertas/debugfs.c
@@ -913,7 +913,10 @@ static ssize_t lbs_debugfs_write(struct file *f, const char __user *buf,
 	char *p2;
 	struct debug_data *d = f->private_data;
 
-	pdata = kmalloc(cnt, GFP_KERNEL);
+	if (cnt == 0)
+		return 0;
+
+	pdata = kmalloc(cnt + 1, GFP_KERNEL);
 	if (pdata == NULL)
 		return 0;
 
@@ -922,6 +925,7 @@ static ssize_t lbs_debugfs_write(struct file *f, const char __user *buf,
 		kfree(pdata);
 		return 0;
 	}
+	pdata[cnt] = '\0';
 
 	p0 = pdata;
 	for (i = 0; i < num_of_items; i++) {
--
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