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

From: David Miller
Date: Thu Aug 09 2012 - 19:16:34 EST


From: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
Date: Thu, 09 Aug 2012 16:50:40 +0400

> 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.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: Ruan Zhijie <ruanzhijie@xxxxxxxxxxx>
> Tested-by: Ruan Zhijie <ruanzhijie@xxxxxxxxxxx>
> Acked-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> Acked-by: Yuchung Cheng <ycheng@xxxxxxxxxx>
> Signed-off-by: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>

Applied, thanks.
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