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[4.2.y-ckt,stable] Patch "tcp: beware of alignments in tcp_get_info()" has been added to the 4.2.y-ckt tree

Message ID 1457390148-2794-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa March 7, 2016, 10:35 p.m. UTC 
This is a note to let you know that I have just added a patch titled

    tcp: beware of alignments in tcp_get_info()

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt5.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

From f948cb89e3febb263715519820a04f9d588d070d Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Wed, 27 Jan 2016 10:52:43 -0800
Subject: tcp: beware of alignments in tcp_get_info()

[ Upstream commit ff5d749772018602c47509bdc0093ff72acd82ec ]

With some combinations of user provided flags in netlink command,
it is possible to call tcp_get_info() with a buffer that is not 8-bytes
aligned.

It does matter on some arches, so we need to use put_unaligned() to
store the u64 fields.

Current iproute2 package does not trigger this particular issue.

Fixes: 0df48c26d841 ("tcp: add tcpi_bytes_acked to tcp_info")
Fixes: 977cb0ecf82e ("tcp: add pacing_rate information into tcp_info")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 net/ipv4/tcp.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--
2.7.0
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Patch

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 45534a5..a7b4cf6 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -279,6 +279,7 @@ 

 #include <asm/uaccess.h>
 #include <asm/ioctls.h>
+#include <asm/unaligned.h>
 #include <net/busy_poll.h>

 int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
@@ -2634,6 +2635,7 @@  void tcp_get_info(struct sock *sk, struct tcp_info *info)
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	u32 now = tcp_time_stamp;
 	unsigned int start;
+	u64 rate64;
 	u32 rate;

 	memset(info, 0, sizeof(*info));
@@ -2698,15 +2700,17 @@  void tcp_get_info(struct sock *sk, struct tcp_info *info)
 	info->tcpi_total_retrans = tp->total_retrans;

 	rate = READ_ONCE(sk->sk_pacing_rate);
-	info->tcpi_pacing_rate = rate != ~0U ? rate : ~0ULL;
+	rate64 = rate != ~0U ? rate : ~0ULL;
+	put_unaligned(rate64, &info->tcpi_pacing_rate);

 	rate = READ_ONCE(sk->sk_max_pacing_rate);
-	info->tcpi_max_pacing_rate = rate != ~0U ? rate : ~0ULL;
+	rate64 = rate != ~0U ? rate : ~0ULL;
+	put_unaligned(rate64, &info->tcpi_max_pacing_rate);

 	do {
 		start = u64_stats_fetch_begin_irq(&tp->syncp);
-		info->tcpi_bytes_acked = tp->bytes_acked;
-		info->tcpi_bytes_received = tp->bytes_received;
+		put_unaligned(tp->bytes_acked, &info->tcpi_bytes_acked);
+		put_unaligned(tp->bytes_received, &info->tcpi_bytes_received);
 	} while (u64_stats_fetch_retry_irq(&tp->syncp, start));
 	info->tcpi_segs_out = tp->segs_out;
 	info->tcpi_segs_in = tp->segs_in;