[PATCH 3.13.y-ckt 38/53] Btrfs: fix memory leak in the extent_same ioctl

[Kamal Mostafa]

3.13.11-ckt25 -stable review patch.  If anyone has any objections, please let me know.

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

From: Filipe Manana <fdmanana at suse.com>

commit 497b4050e0eacd4c746dd396d14916b1e669849d upstream.

We were allocating memory with memdup_user() but we were never releasing
that memory. This affected pretty much every call to the ioctl, whether
it deduplicated extents or not.

This issue was reported on IRC by Julian Taylor and on the mailing list
by Marcel Ritter, credit goes to them for finding the issue.

Reported-by: Julian Taylor <jtaylor.debian at googlemail.com>
Reported-by: Marcel Ritter <ritter.marcel at gmail.com>
Signed-off-by: Filipe Manana <fdmanana at suse.com>
Reviewed-by: Mark Fasheh <mfasheh at suse.de>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/btrfs/ioctl.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 05f5c87..3152235 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2698,7 +2698,7 @@ static long btrfs_ioctl_file_extent_same(struct file *file,
 					 void __user *argp)
 {
 	struct btrfs_ioctl_same_args tmp;
-	struct btrfs_ioctl_same_args *same;
+	struct btrfs_ioctl_same_args *same = NULL;
 	struct btrfs_ioctl_same_extent_info *info;
 	struct inode *src = file->f_dentry->d_inode;
 	struct file *dst_file = NULL;
@@ -2732,6 +2732,7 @@ static long btrfs_ioctl_file_extent_same(struct file *file,
 
 	if (IS_ERR(same)) {
 		ret = PTR_ERR(same);
+		same = NULL;
 		goto out;
 	}
 
@@ -2819,6 +2820,7 @@ next:
 
 out:
 	mnt_drop_write_file(file);
+	kfree(same);
 	return ret;
 }
 
-- 
1.9.1