Btrfs: fix memory leak in the extent_same ioctl

[ Upstream commit 497b4050e0eacd4c746dd396d14916b1e669849d ]

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@googlemail.com>
Reported-by: Marcel Ritter <ritter.marcel@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 1cecf25fa14f892683de026f3e6d843bed2bc523..3d50f1ee51baa8667b5c1bde32ac73d79855fc19 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2959,7 +2959,7 @@ out_unlock:
 static long btrfs_ioctl_file_extent_same(struct file *file,
                        struct btrfs_ioctl_same_args __user *argp)
 {
-       struct btrfs_ioctl_same_args *same;
+       struct btrfs_ioctl_same_args *same = NULL;
        struct btrfs_ioctl_same_extent_info *info;
        struct inode *src = file_inode(file);
        u64 off;
@@ -2989,6 +2989,7 @@ static long btrfs_ioctl_file_extent_same(struct file *file,
 
        if (IS_ERR(same)) {
                ret = PTR_ERR(same);
+               same = NULL;
                goto out;
        }
 
@@ -3059,6 +3060,7 @@ static long btrfs_ioctl_file_extent_same(struct file *file,
 
 out:
        mnt_drop_write_file(file);
+       kfree(same);
        return ret;
 }