[PATCH 4.4 08/20] tcp: fix tcp_fastopen unaligned access complaints on sparc

From: Greg Kroah-Hartman
Date: Thu Feb 02 2017 - 13:35:00 EST


4.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Shannon Nelson <shannon.nelson@xxxxxxxxxx>


[ Upstream commit 003c941057eaa868ca6fedd29a274c863167230d ]

Fix up a data alignment issue on sparc by swapping the order
of the cookie byte array field with the length field in
struct tcp_fastopen_cookie, and making it a proper union
to clean up the typecasting.

This addresses log complaints like these:
log_unaligned: 113 callbacks suppressed
Kernel unaligned access at TPC[976490] tcp_try_fastopen+0x2d0/0x360
Kernel unaligned access at TPC[9764ac] tcp_try_fastopen+0x2ec/0x360
Kernel unaligned access at TPC[9764c8] tcp_try_fastopen+0x308/0x360
Kernel unaligned access at TPC[9764e4] tcp_try_fastopen+0x324/0x360
Kernel unaligned access at TPC[976490] tcp_try_fastopen+0x2d0/0x360

Cc: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: Shannon Nelson <shannon.nelson@xxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/tcp.h | 7 ++++++-
net/ipv4/tcp_fastopen.c | 2 +-
2 files changed, 7 insertions(+), 2 deletions(-)

--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -56,8 +56,13 @@ static inline unsigned int tcp_optlen(co

/* TCP Fast Open Cookie as stored in memory */
struct tcp_fastopen_cookie {
+ union {
+ u8 val[TCP_FASTOPEN_COOKIE_MAX];
+#if IS_ENABLED(CONFIG_IPV6)
+ struct in6_addr addr;
+#endif
+ };
s8 len;
- u8 val[TCP_FASTOPEN_COOKIE_MAX];
bool exp; /* In RFC6994 experimental option format */
};

--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -112,7 +112,7 @@ static bool tcp_fastopen_cookie_gen(stru
struct tcp_fastopen_cookie tmp;

if (__tcp_fastopen_cookie_gen(&ip6h->saddr, &tmp)) {
- struct in6_addr *buf = (struct in6_addr *) tmp.val;
+ struct in6_addr *buf = &tmp.addr;
int i;

for (i = 0; i < 4; i++)