->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>
---
Changes since v1:
- move sk_shutdown into a separate byte instead of locking
AF_UNIX sockets.
Changes since v2:
- reorder bitfields, so that sk_type/sk_protocol still fit in
separate 2-bytes/byte.
include/net/sock.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index c9c8b19..1c019d4 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -383,12 +383,11 @@ struct sock {
int sk_sndbuf;
struct sk_buff_head sk_write_queue;
kmemcheck_bitfield_begin(flags);
- unsigned int sk_shutdown : 2,
+ unsigned int sk_type : 16,
+ sk_protocol : 8,
sk_no_check_tx : 1,
sk_no_check_rx : 1,
- sk_userlocks : 4,
- sk_protocol : 8,
- sk_type : 16;
+ sk_userlocks : 4;
#define SK_PROTOCOL_MAX U8_MAX
kmemcheck_bitfield_end(flags);
int sk_wmem_queued;
@@ -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;
--
2.7.3
