Commit fc64869c authored May 18, 2016 by Andrey Ryabinin Committed by David S. Miller May 20, 2016

net: sock: move ->sk_shutdown out of bitfields.



->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 <aryabinin@virtuozzo.com>
Suggested-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 911f6b1f

include/net/sock.h

+8 −1

Original line number	Diff line number	Diff line
		@@ -382,8 +382,13 @@ struct sock {
		atomic_t sk_omem_alloc;
		int sk_sndbuf;
		struct sk_buff_head sk_write_queue;

		/*
		* Because of non atomicity rules, all
		* changes are protected by socket lock.
		*/
		kmemcheck_bitfield_begin(flags);
		unsigned int sk_shutdown : 2,
		unsigned int sk_padding : 2,
		sk_no_check_tx : 1,
		sk_no_check_rx : 1,
		sk_userlocks : 4,
		@@ -391,6 +396,7 @@ struct sock {
		sk_type : 16;
		#define SK_PROTOCOL_MAX U8_MAX
		kmemcheck_bitfield_end(flags);

		int sk_wmem_queued;
		gfp_t sk_allocation;
		u32 sk_pacing_rate; /* bytes per second */
		@@ -418,6 +424,7 @@ 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;

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