Btrfs: fix memory leak in the extent_same ioctl

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@googlemail.com>
Reported-by: Marcel Ritter <ritter.marcel@gmail.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 3e16042338e497de38ee1ba2530ebdf6d0c59c63..d40ae42ba6d4b5ade2384263110758482e6c8e6f 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2743,7 +2743,7 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 len,
 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;
@@ -2773,6 +2773,7 @@ static long btrfs_ioctl_file_extent_same(struct file *file,
 
        if (IS_ERR(same)) {
                ret = PTR_ERR(same);
+               same = NULL;
                goto out;
        }
 
@@ -2843,6 +2844,7 @@ static long btrfs_ioctl_file_extent_same(struct file *file,
 
 out:
        mnt_drop_write_file(file);
+       kfree(same);
        return ret;
 }