Merge branch 'ipv6-data-races'

Eric Dumazet says:

====================
ipv6: round of data-races fixes

This series is inspired by one related syzbot report.

Many inet6_sk(sk) fields reads or writes are racy.

Move 1-bit fields to inet->inet_flags to provide
atomic safety. inet6_{test|set|clear|assign}_bit() helpers
could be changed later if we need to make room in inet_flags.

Also add missing READ_ONCE()/WRITE_ONCE() when
lockless readers need access to specific fields.

np->srcprefs will be handled separately to avoid merge conflicts
because a prior patch was posted for net tree.
====================

Signed-off-by: David S. Miller <[email protected]>

1 files changed, 16 insertions, 33 deletions

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index af8a771a053c..09253825c99c 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -213,28 +213,9 @@ struct ipv6_pinfo {
 	__be32			flow_label;
 	__u32			frag_size;
 
-	/*
-	 * Packed in 16bits.
-	 * Omit one shift by putting the signed field at MSB.
-	 */
-#if defined(__BIG_ENDIAN_BITFIELD)
-	__s16			hop_limit:9;
-	__u16			__unused_1:7;
-#else
-	__u16			__unused_1:7;
-	__s16			hop_limit:9;
-#endif
+	s16			hop_limit;
+	u8			mcast_hops;
 
-#if defined(__BIG_ENDIAN_BITFIELD)
-	/* Packed in 16bits. */
-	__s16			mcast_hops:9;
-	__u16			__unused_2:6,
-				mc_loop:1;
-#else
-	__u16			mc_loop:1,
-				__unused_2:6;
-	__s16			mcast_hops:9;
-#endif
 	int			ucast_oif;
 	int			mcast_oif;
 
@@ -262,21 +243,11 @@ struct ipv6_pinfo {
 	} rxopt;
 
 	/* sockopt flags */
-	__u16			recverr:1,
-	                        sndflow:1,
-				repflow:1,
-				pmtudisc:3,
-				padding:1,	/* 1 bit hole */
-				srcprefs:3,	/* 001: prefer temporary address
+	__u8			srcprefs:3;	/* 001: prefer temporary address
 						 * 010: prefer public address
 						 * 100: prefer care-of address
 						 */
-				dontfrag:1,
-				autoflowlabel:1,
-				autoflowlabel_set:1,
-				mc_all:1,
-				recverr_rfc4884:1,
-				rtalert_isolate:1;
+	__u8			pmtudisc;
 	__u8			min_hopcount;
 	__u8			tclass;
 	__be32			rcv_flowinfo;
@@ -293,6 +264,18 @@ struct ipv6_pinfo {
 	struct inet6_cork	cork;
 };
 
+/* We currently use available bits from inet_sk(sk)->inet_flags,
+ * this could change in the future.
+ */
+#define inet6_test_bit(nr, sk)			\
+	test_bit(INET_FLAGS_##nr, &inet_sk(sk)->inet_flags)
+#define inet6_set_bit(nr, sk)			\
+	set_bit(INET_FLAGS_##nr, &inet_sk(sk)->inet_flags)
+#define inet6_clear_bit(nr, sk)			\
+	clear_bit(INET_FLAGS_##nr, &inet_sk(sk)->inet_flags)
+#define inet6_assign_bit(nr, sk, val)		\
+	assign_bit(INET_FLAGS_##nr, &inet_sk(sk)->inet_flags, val)
+
 /* WARNING: don't change the layout of the members in {raw,udp,tcp}6_sock! */
 struct raw6_sock {
 	/* inet_sock has to be the first member of raw6_sock */