From: David Sterba Date: Wed, 4 May 2016 09:32:00 +0000 (+0200) Subject: btrfs: add write protection to SET_FEATURES ioctl X-Git-Tag: v4.5.7~10 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e5788f9679c122730e1f9978aa8413516dca7b17;p=thirdparty%2Fkernel%2Fstable.git btrfs: add write protection to SET_FEATURES ioctl commit 7ab19625a911f7568ec85302e3aa7a64186006c8 upstream. Perform the want_write check if we get far enough to do any writes. Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index ea21e588a8392..14e291422ab11 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -5397,9 +5397,15 @@ static int btrfs_ioctl_set_features(struct file *file, void __user *arg) if (ret) return ret; + ret = mnt_want_write_file(file); + if (ret) + return ret; + trans = btrfs_start_transaction(root, 0); - if (IS_ERR(trans)) - return PTR_ERR(trans); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + goto out_drop_write; + } spin_lock(&root->fs_info->super_lock); newflags = btrfs_super_compat_flags(super_block); @@ -5418,7 +5424,11 @@ static int btrfs_ioctl_set_features(struct file *file, void __user *arg) btrfs_set_super_incompat_flags(super_block, newflags); spin_unlock(&root->fs_info->super_lock); - return btrfs_commit_transaction(trans, root); + ret = btrfs_commit_transaction(trans, root); +out_drop_write: + mnt_drop_write_file(file); + + return ret; } long btrfs_ioctl(struct file *file, unsigned int