Patch "CIFS: fix type confusion in copy offload ioctl" has been added to the 3.14-stable tree

Patch "CIFS: fix type confusion in copy offload ioctl" has been added to the 3.14-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    CIFS: fix type confusion in copy offload ioctl

to the 3.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     cifs-fix-type-confusion-in-copy-offload-ioctl.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 4c17a6d56bb0cad3066a714e94f7185a24b40f49 Mon Sep 17 00:00:00 2001
From: Jann Horn <jann@thejh.net>
Date: Fri, 11 Sep 2015 16:27:27 +0200
Subject: CIFS: fix type confusion in copy offload ioctl

From: Jann Horn <jann@thejh.net>

commit 4c17a6d56bb0cad3066a714e94f7185a24b40f49 upstream.

This might lead to local privilege escalation (code execution as
kernel) for systems where the following conditions are met:

 - CONFIG_CIFS_SMB2 and CONFIG_CIFS_POSIX are enabled
 - a cifs filesystem is mounted where:
  - the mount option "vers" was used and set to a value >=2.0
  - the attacker has write access to at least one file on the filesystem

To attack this, an attacker would have to guess the target_tcon
pointer (but guessing wrong doesn't cause a crash, it just returns an
error code) and win a narrow race.

Signed-off-by: Jann Horn <jann@thejh.net>
Signed-off-by: Steve French <smfrench@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/cifs/ioctl.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/fs/cifs/ioctl.c
+++ b/fs/cifs/ioctl.c
@@ -67,6 +67,12 @@ static long cifs_ioctl_clone(unsigned in
 		goto out_drop_write;
 	}
 
+	if (src_file.file->f_op->unlocked_ioctl != cifs_ioctl) {
+		rc = -EBADF;
+		cifs_dbg(VFS, "src file seems to be from a different filesystem type\n");
+		goto out_fput;
+	}
+
 	if ((!src_file.file->private_data) || (!dst_file->private_data)) {
 		rc = -EBADF;
 		cifs_dbg(VFS, "missing cifsFileInfo on copy range src file\n");


Patches currently in stable-queue which might be from jann@thejh.net are

queue-3.14/cifs-fix-type-confusion-in-copy-offload-ioctl.patch