linux-kernel - [PATCH v1 net 11/16] net: Fix a data-race around sysctl

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Message-ID: <20220706052130.16368-12-kuniyu@amazon.com>
Date:   Tue, 5 Jul 2022 22:21:25 -0700
From:   Kuniyuki Iwashima <kuniyu@...zon.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Iurii Zaikin <yzaikin@...gle.com>
CC:     Kuniyuki Iwashima <kuniyu@...zon.com>,
        Kuniyuki Iwashima <kuni1840@...il.com>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Satoru Moriya <satoru.moriya@....com>,
        "Steven Rostedt" <rostedt@...dmis.org>
Subject: [PATCH v1 net 11/16] net: Fix a data-race around sysctl_mem.

While reading .sysctl_mem, it can be changed concurrently.  So, we need to
add READ_ONCE().  Then we can set proc_doulongvec_minmax_lockless() as the
handler to mark it safe.

Fixes: 3847ce32aea9 ("core: add tracepoints for queueing skb to rcvbuf")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
CC: Satoru Moriya <satoru.moriya@....com>
CC: Steven Rostedt <rostedt@...dmis.org>
---
 include/net/sock.h             | 2 +-
 include/trace/events/sock.h    | 6 +++---
 net/decnet/sysctl_net_decnet.c | 2 +-
 net/ipv4/sysctl_net_ipv4.c     | 4 ++--
 net/sctp/sysctl.c              | 2 +-
 5 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 72ca97ccb460..9fa54762e077 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1529,7 +1529,7 @@ void __sk_mem_reclaim(struct sock *sk, int amount);
 /* sysctl_mem values are in pages, we convert them in SK_MEM_QUANTUM units */
 static inline long sk_prot_mem_limits(const struct sock *sk, int index)
 {
-	long val = sk->sk_prot->sysctl_mem[index];
+	long val = READ_ONCE(sk->sk_prot->sysctl_mem[index]);
 
 #if PAGE_SIZE > SK_MEM_QUANTUM
 	val <<= PAGE_SHIFT - SK_MEM_QUANTUM_SHIFT;
diff --git a/include/trace/events/sock.h b/include/trace/events/sock.h
index 12c315782766..3c36c2812782 100644
--- a/include/trace/events/sock.h
+++ b/include/trace/events/sock.h
@@ -122,9 +122,9 @@ TRACE_EVENT(sock_exceed_buf_limit,
 
 	TP_printk("proto:%s sysctl_mem=%ld,%ld,%ld allocated=%ld sysctl_rmem=%d rmem_alloc=%d sysctl_wmem=%d wmem_alloc=%d wmem_queued=%d kind=%s",
 		__entry->name,
-		__entry->sysctl_mem[0],
-		__entry->sysctl_mem[1],
-		__entry->sysctl_mem[2],
+		READ_ONCE(__entry->sysctl_mem[0]),
+		READ_ONCE(__entry->sysctl_mem[1]),
+		READ_ONCE(__entry->sysctl_mem[2]),
 		__entry->allocated,
 		__entry->sysctl_rmem,
 		__entry->rmem_alloc,
diff --git a/net/decnet/sysctl_net_decnet.c b/net/decnet/sysctl_net_decnet.c
index 67b5ab2657b7..e7e658f1ba67 100644
--- a/net/decnet/sysctl_net_decnet.c
+++ b/net/decnet/sysctl_net_decnet.c
@@ -315,7 +315,7 @@ static struct ctl_table dn_table[] = {
 		.data = &sysctl_decnet_mem,
 		.maxlen = sizeof(sysctl_decnet_mem),
 		.mode = 0644,
-		.proc_handler = proc_doulongvec_minmax
+		.proc_handler = proc_doulongvec_minmax_lockless,
 	},
 	{
 		.procname = "decnet_rmem",
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index eea11218a663..b14931ca5c85 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -504,7 +504,7 @@ static struct ctl_table ipv4_table[] = {
 		.maxlen		= sizeof(sysctl_tcp_mem),
 		.data		= &sysctl_tcp_mem,
 		.mode		= 0644,
-		.proc_handler	= proc_doulongvec_minmax,
+		.proc_handler	= proc_doulongvec_minmax_lockless,
 	},
 	{
 		.procname	= "tcp_low_latency",
@@ -570,7 +570,7 @@ static struct ctl_table ipv4_table[] = {
 		.data		= &sysctl_udp_mem,
 		.maxlen		= sizeof(sysctl_udp_mem),
 		.mode		= 0644,
-		.proc_handler	= proc_doulongvec_minmax,
+		.proc_handler	= proc_doulongvec_minmax_lockless,
 	},
 	{
 		.procname	= "fib_sync_mem",
diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
index b46a416787ec..fa79bf4059d1 100644
--- a/net/sctp/sysctl.c
+++ b/net/sctp/sysctl.c
@@ -64,7 +64,7 @@ static struct ctl_table sctp_table[] = {
 		.data		= &sysctl_sctp_mem,
 		.maxlen		= sizeof(sysctl_sctp_mem),
 		.mode		= 0644,
-		.proc_handler	= proc_doulongvec_minmax
+		.proc_handler	= proc_doulongvec_minmax_lockless,
 	},
 	{
 		.procname	= "sctp_rmem",
-- 
2.30.2