On Wed, 2016-05-18 at 15:03 +0300, Andrey Ryabinin wrote:
> ->sk_shutdown bits share one bitfield with some other bits in sock struct,
> such as ->sk_no_check_[r,t]x, ->sk_userlocks ...
> sock_setsockopt() may write to these bits, while holding the socket lock.
>
> In case of AF_UNIX sockets, we change ->sk_shutdown bits while holding only
> unix_state_lock(). So concurrent setsockopt() and shutdown() may lead
> to corrupting these bits.
>
> Fix this by moving ->sk_shutdown bits out of bitfield into a separate byte.
> This will not change the 'struct sock' size since ->sk_shutdown moved into
> previously unused 16-bit hole.
>
> Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com>
> Suggested-by: Hannes Frederic Sowa <han...@stressinduktion.org>
> ---
> include/net/sock.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/sock.h b/include/net/sock.h
> index c9c8b19..04dc131 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -383,8 +383,7 @@ struct sock {
> int sk_sndbuf;
> struct sk_buff_head sk_write_queue;
> kmemcheck_bitfield_begin(flags);
> - unsigned int sk_shutdown : 2,
Please replace by a padding, so that sk_protocol is sill a byte,
not 8 bits spaning 2 bytes in memory.
> - sk_no_check_tx : 1,
> + unsigned int sk_no_check_tx : 1,
> sk_no_check_rx : 1,
> sk_userlocks : 4,
> sk_protocol : 8,
> @@ -418,6 +417,7 @@ struct sock {
> struct timer_list sk_timer;
> ktime_t sk_stamp;
> u16 sk_tsflags;
> + u8 sk_shutdown;
> u32 sk_tskey;
> struct socket *sk_socket;
> void *sk_user_data;
Thanks.
