[PATCH 3.2 177/185] libertas: potential oops in debugfs

[Ben Hutchings]

3.2.54-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

commit a497e47d4aec37aaf8f13509f3ef3d1f6a717d88 upstream.

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@xxxxxxxxx>
Reported-by: Fabian Yamaguchi <fabs@xxxxxxxxx>
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Acked-by: Dan Williams <dcbw@xxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/net/wireless/libertas/debugfs.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/net/wireless/libertas/debugfs.c
+++ b/drivers/net/wireless/libertas/debugfs.c
@@ -919,7 +919,10 @@ static ssize_t lbs_debugfs_write(struct
 	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;
 
@@ -928,6 +931,7 @@ static ssize_t lbs_debugfs_write(struct
 		kfree(pdata);
 		return 0;
 	}
+	pdata[cnt] = '\0';
 
 	p0 = pdata;
 	for (i = 0; i < num_of_items; i++) {

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