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: Jiri Slaby <jslaby@suse.cz>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index d43cd15c3097c2573ccc24dff8129b3442769b9b..5f597cf570bee72b3c860c721a9bbc52d3a6bb30 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2707,7 +2707,7 @@ 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;
@@ -2833,6 +2833,7 @@ static long btrfs_ioctl_file_extent_same(struct file *file,
 
 out:
        mnt_drop_write_file(file);
+       kfree(same);
        return ret;
 }