Re: [RFC PATCH] tun: don't zeroize sock->file on detach

From: Yuchung Cheng <redacted>
Date: Wed, 8 Aug 2012 10:48:32 -0700

On Wed, Aug 8, 2012 at 5:53 AM, Stanislav Kinsbursky
[off-list ref] wrote:

quoted

Hi, Dave.
What about this patch?


On Wed, Jul 11, 2012 at 03:48:20PM +0400, Stanislav Kinsbursky wrote:

quoted

This is a fix for bug, introduced in 3.4 kernel by commit
1ab5ecb90cb6a3df1476e052f76a6e8f6511cb3d, which, among other things,
replaced
simple sock_put() by sk_release_kernel(). Below is sequence, which leads
to
oops for non-persistent devices:

tun_chr_close()
tun_detach()                            <== tun->socket.file = NULL
tun_free_netdev()
sk_release_sock()
sock_release(sock->file == NULL)
iput(SOCK_INODE(sock))                  <== dereference on NULL pointer

This patch just removes zeroing of socket's file from __tun_detach().
sock_release() will do this.

Signed-off-by: Stanislav Kinsbursky <redacted>

Acked-by: Yuchung Cheng <redacted>

I has tested this patch and it works (so my kernel stops crashing
using tun devices).

This patch needs to be formally resubmitted to netdev.