From: Filipe Manana <fdmanana@suse.com>
Date: Fri, 14 Dec 2018 19:45:22 +0000 (+0000)
Subject: Btrfs: do not overwrite error return value in the get device stats ioctl
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=eee995775444b50a74ac479ee98ff88e6df1b01b;p=linux.git

Btrfs: do not overwrite error return value in the get device stats ioctl

If the call to btrfs_get_dev_stats() failed we would overwrite the error
returned to user space with -EFAULT if the call to copy_to_user() failed
as well. Fix that by calling copy_to_user() only if btrfs_get_dev_stats()
returned success.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 02ea03d220e86..7ff60217ec552 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4438,7 +4438,7 @@ static long btrfs_ioctl_get_dev_stats(struct btrfs_fs_info *fs_info,
 
 	ret = btrfs_get_dev_stats(fs_info, sa);
 
-	if (copy_to_user(arg, sa, sizeof(*sa)))
+	if (ret == 0 && copy_to_user(arg, sa, sizeof(*sa)))
 		ret = -EFAULT;
 
 	kfree(sa);