Commit 59cd0cbc authored May 08, 2007 by Darrick J. Wong Committed by Linus Torvalds May 08, 2007

Fix race between proc_readdir and remove_proc_entry



Fix the following race:

proc_readdir				remove_proc_entry
============				=================

spin_lock(&proc_subdir_lock);
[choose PDE to start filldir from]
spin_unlock(&proc_subdir_lock);
					spin_lock(&proc_subdir_lock);
					[find PDE]
					[free PDE, refcount is 0]
					spin_unlock(&proc_subdir_lock);
		    /* boom */
if (filldir(dirent, de->name, ...

[de_put on error path --adobriyan]
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 7695650a

fs/proc/generic.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -478,14 +478,21 @@ int proc_readdir(struct file * filp,
		}

		do {
		struct proc_dir_entry *next;

		/* filldir passes info to user space */
		de_get(de);
		spin_unlock(&proc_subdir_lock);
		if (filldir(dirent, de->name, de->namelen, filp->f_pos,
		de->low_ino, de->mode >> 12) < 0)
		de->low_ino, de->mode >> 12) < 0) {
		de_put(de);
		goto out;
		}
		spin_lock(&proc_subdir_lock);
		filp->f_pos++;
		de = de->next;
		next = de->next;
		de_put(de);
		de = next;
		} while (de);
		spin_unlock(&proc_subdir_lock);
		}

Admin message