From: Greg KH <gregkh@linuxfoundation.org>
To: Peter Collingbourne <pcc@google.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Colin Ian King <colin.king@canonical.com>,
Cong Wang <cong.wang@bytedance.com>,
Al Viro <viro@zeniv.linux.org.uk>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] net: don't unconditionally copy_from_user a struct ifreq for socket ioctls
Date: Thu, 26 Aug 2021 08:39:44 +0200 [thread overview]
Message-ID: <YSc3MGVllU8qSJXV@kroah.com> (raw)
In-Reply-To: <20210826012722.3210359-1-pcc@google.com>
On Wed, Aug 25, 2021 at 06:27:22PM -0700, Peter Collingbourne wrote:
> A common implementation of isatty(3) involves calling a ioctl passing
> a dummy struct argument and checking whether the syscall failed --
> bionic and glibc use TCGETS (passing a struct termios), and musl uses
> TIOCGWINSZ (passing a struct winsize). If the FD is a socket, we will
> copy sizeof(struct ifreq) bytes of data from the argument and return
> -EFAULT if that fails. The result is that the isatty implementations
> may return a non-POSIX-compliant value in errno in the case where part
> of the dummy struct argument is inaccessible, as both struct termios
> and struct winsize are smaller than struct ifreq (at least on arm64).
>
> Although there is usually enough stack space following the argument
> on the stack that this did not present a practical problem up to now,
> with MTE stack instrumentation it's more likely for the copy to fail,
> as the memory following the struct may have a different tag.
>
> Fix the problem by adding an early check for whether the ioctl is a
> valid socket ioctl, and return -ENOTTY if it isn't.
>
> Fixes: 44c02a2c3dc5 ("dev_ioctl(): move copyin/copyout to callers")
> Link: https://linux-review.googlesource.com/id/I869da6cf6daabc3e4b7b82ac979683ba05e27d4d
> Signed-off-by: Peter Collingbourne <pcc@google.com>
> Cc: <stable@vger.kernel.org> # 4.19
> ---
> include/linux/netdevice.h | 1 +
> net/core/dev_ioctl.c | 64 ++++++++++++++++++++++++++++++++-------
> net/socket.c | 6 +++-
> 3 files changed, 59 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index eaf5bb008aa9..481b90ef0d32 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -4012,6 +4012,7 @@ int netdev_rx_handler_register(struct net_device *dev,
> void netdev_rx_handler_unregister(struct net_device *dev);
>
> bool dev_valid_name(const char *name);
> +bool is_dev_ioctl_cmd(unsigned int cmd);
"is_socket_ioctl_cmd()" might be a better global name here.
thanks,
greg k-h
next prev parent reply other threads:[~2021-08-26 6:39 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-26 1:27 [PATCH] net: don't unconditionally copy_from_user a struct ifreq for socket ioctls Peter Collingbourne
2021-08-26 6:39 ` Greg KH [this message]
2021-08-26 19:46 ` Peter Collingbourne
2021-08-26 8:12 ` David Laight
2021-08-26 19:46 ` Peter Collingbourne
2021-08-27 8:34 ` David Laight
2021-08-26 8:58 ` Arnd Bergmann
2021-08-26 19:46 ` Peter Collingbourne
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