From ebiederm@xmission.com Tue Sep 21 15:25:56 2010 From: Eric W. Biederman To: Greg Kroah-Hartman Cc: Tejun Heo , Hugh Dickins Date: Mon, 20 Sep 2010 00:56:27 -0700 Message-ID: Subject: sysfs: Fail bin file mmap if vma close is implemented. From: Eric W. Biederman It is not reasonably possible to wrap vma->close(). To correctly wrap close would imply calling close on any vmas that remain when sysfs_remove_bin_file is called. Finding the proper lists walking them getting the locking right etc, requires deep knowledge of the mm subsystem and as such would require assistence from the mm subsystem to implement. That assistence does not currently exist. Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/bin.c | 26 ++++++++------------------ 1 file changed, 8 insertions(+), 18 deletions(-) --- a/fs/sysfs/bin.c +++ b/fs/sysfs/bin.c @@ -190,23 +190,6 @@ static void bin_vma_open(struct vm_area_ sysfs_put_active(attr_sd); } -static void bin_vma_close(struct vm_area_struct *vma) -{ - struct file *file = vma->vm_file; - struct bin_buffer *bb = file->private_data; - struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata; - - if (!bb->vm_ops || !bb->vm_ops->close) - return; - - if (!sysfs_get_active(attr_sd)) - return; - - bb->vm_ops->close(vma); - - sysfs_put_active(attr_sd); -} - static int bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf) { struct file *file = vma->vm_file; @@ -331,7 +314,6 @@ static int bin_migrate(struct vm_area_st static const struct vm_operations_struct bin_vm_ops = { .open = bin_vma_open, - .close = bin_vma_close, .fault = bin_fault, .page_mkwrite = bin_page_mkwrite, .access = bin_access, @@ -377,6 +359,14 @@ static int mmap(struct file *file, struc if (bb->mmapped && bb->vm_ops != vma->vm_ops) goto out_put; + /* + * It is not possible to successfully wrap close. + * So error if someone is trying to use close. + */ + rc = -EINVAL; + if (vma->vm_ops && vma->vm_ops->close) + goto out_put; + rc = 0; bb->mmapped = 1; bb->vm_ops = vma->vm_ops;