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Commit 2f36db71 authored by Jann Horn's avatar Jann Horn Committed by Linus Torvalds
Browse files

ecryptfs: forbid opening files without mmap handler 



This prevents users from triggering a stack overflow through a recursive
invocation of pagefault handling that involves mapping procfs files into
virtual memory.

Signed-off-by: default avatarJann Horn <jannh@google.com>
Acked-by: default avatarTyler Hicks <tyhicks@canonical.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e54ad7f1

fs/ecryptfs/kthread.c

+11 −2
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <linux/slab.h>

#include <linux/wait.h>

#include <linux/mount.h>

#include <linux/file.h>

#include "ecryptfs_kernel.h"



struct ecryptfs_open_req {
@@ -147,7 +148,7 @@ int ecryptfs_privileged_open(struct file **lower_file, 
	flags |= IS_RDONLY(d_inode(lower_dentry)) ? O_RDONLY : O_RDWR;

	(*lower_file) = dentry_open(&req.path, flags, cred);

	if (!IS_ERR(*lower_file))

		goto out;

		goto have_file;

	if ((flags & O_ACCMODE) == O_RDONLY) {

		rc = PTR_ERR((*lower_file));

		goto out;
@@ -165,8 +166,16 @@ int ecryptfs_privileged_open(struct file **lower_file, 
	mutex_unlock(&ecryptfs_kthread_ctl.mux);

	wake_up(&ecryptfs_kthread_ctl.wait);

	wait_for_completion(&req.done);

	if (IS_ERR(*lower_file))

	if (IS_ERR(*lower_file)) {

		rc = PTR_ERR(*lower_file);

		goto out;

	}

have_file:

	if ((*lower_file)->f_op->mmap == NULL) {

		fput(*lower_file);

		*lower_file = NULL;

		rc = -EMEDIUMTYPE;

	}

out:

	return rc;

}