Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
  [PATCH] sanitize locate_fd()
  [PATCH] sanitize unshare_files/reset_files_struct
  [PATCH] sanitize handling of shared descriptor tables in failing execve()
  [PATCH] close race in unshare_files()
  [PATCH] restore sane ->umount_begin() API
  cifs: timeout dfs automounts +little fix.

1 files changed, 14 insertions, 26 deletions

diff --git a/fs/fcntl.c b/fs/fcntl.c
index e632da761fc..3f3ac630ccd 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -55,14 +55,16 @@ static int get_close_on_exec(unsigned int fd)
  * file_lock held for write.
  */
 
-static int locate_fd(struct files_struct *files, 
-			    struct file *file, unsigned int orig_start)
+static int locate_fd(unsigned int orig_start, int cloexec)
 {
+	struct files_struct *files = current->files;
 	unsigned int newfd;
 	unsigned int start;
 	int error;
 	struct fdtable *fdt;
 
+	spin_lock(&files->file_lock);
+
 	error = -EINVAL;
 	if (orig_start >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
 		goto out;
@@ -97,42 +99,28 @@ repeat:
 	if (error)
 		goto repeat;
 
-	/*
-	 * We reacquired files_lock, so we are safe as long as
-	 * we reacquire the fdtable pointer and use it while holding
-	 * the lock, no one can free it during that time.
-	 */
 	if (start <= files->next_fd)
 		files->next_fd = newfd + 1;
 
+	FD_SET(newfd, fdt->open_fds);
+	if (cloexec)
+		FD_SET(newfd, fdt->close_on_exec);
+	else
+		FD_CLR(newfd, fdt->close_on_exec);
 	error = newfd;
-	
+
 out:
+	spin_unlock(&files->file_lock);
 	return error;
 }
 
 static int dupfd(struct file *file, unsigned int start, int cloexec)
 {
-	struct files_struct * files = current->files;
-	struct fdtable *fdt;
-	int fd;
-
-	spin_lock(&files->file_lock);
-	fd = locate_fd(files, file, start);
-	if (fd >= 0) {
-		/* locate_fd() may have expanded fdtable, load the ptr */
-		fdt = files_fdtable(files);
-		FD_SET(fd, fdt->open_fds);
-		if (cloexec)
-			FD_SET(fd, fdt->close_on_exec);
-		else
-			FD_CLR(fd, fdt->close_on_exec);
-		spin_unlock(&files->file_lock);
+	int fd = locate_fd(start, cloexec);
+	if (fd >= 0)
 		fd_install(fd, file);
-	} else {
-		spin_unlock(&files->file_lock);
+	else
 		fput(file);
-	}
 
 	return fd;
 }