[PATCH 5.18 59/88] net: Fix data-races around sysctl_[rw]mem(_offset)?.

Greg Kroah-Hartman
2022-08-01T12:20:15Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 02739545951ad4c1215160db7fbf9b7a918d3c0b ]

While reading these sysctl variables, they can be changed concurrently.
Thus, we need to add READ_ONCE() to their readers.

- .sysctl_rmem
- .sysctl_rwmem
- .sysctl_rmem_offset
- .sysctl_wmem_offset
- sysctl_tcp_rmem[1, 2]
- sysctl_tcp_wmem[1, 2]
- sysctl_decnet_rmem[1]
- sysctl_decnet_wmem[1]
- sysctl_tipc_rmem[1]

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/sock.h | 8 ++++----
net/decnet/af_decnet.c | 4 ++--
net/ipv4/tcp.c | 6 +++---
net/ipv4/tcp_input.c | 13 +++++++------
net/ipv4/tcp_output.c | 2 +-
net/mptcp/protocol.c | 6 +++---
net/tipc/socket.c | 2 +-
7 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 6bef0ffb1e7b..9563a093fdfc 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2834,18 +2834,18 @@ static inline int sk_get_wmem0(const struct sock *sk, const struct proto *proto)
{
/* Does this proto have per netns sysctl_wmem ? */
if (proto->sysctl_wmem_offset)
- return *(int *)((void *)sock_net(sk) + proto->sysctl_wmem_offset);
+ return READ_ONCE(*(int *)((void *)sock_net(sk) + proto->sysctl_wmem_offset));

- return *proto->sysctl_wmem;
+ return READ_ONCE(*proto->sysctl_wmem);
}

static inline int sk_get_rmem0(const struct sock *sk, const struct proto *proto)
{
/* Does this proto have per netns sysctl_rmem ? */
if (proto->sysctl_rmem_offset)
- return *(int *)((void *)sock_net(sk) + proto->sysctl_rmem_offset);
+ return READ_ONCE(*(int *)((void *)sock_net(sk) + proto->sysctl_rmem_offset));

- return *proto->sysctl_rmem;
+ return READ_ONCE(*proto->sysctl_rmem);
}

/* Default TCP Small queue budget is ~1 ms of data (1sec >> 10)
diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c
index dc92a67baea3..7d542eb46172 100644
--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c
@@ -480,8 +480,8 @@ static struct sock *dn_alloc_sock(struct net *net, struct socket *sock, gfp_t gf
sk->sk_family = PF_DECnet;
sk->sk_protocol = 0;
sk->sk_allocation = gfp;
- sk->sk_sndbuf = sysctl_decnet_wmem[1];
- sk->sk_rcvbuf = sysctl_decnet_rmem[1];
+ sk->sk_sndbuf = READ_ONCE(sysctl_decnet_wmem[1]);
+ sk->sk_rcvbuf = READ_ONCE(sysctl_decnet_rmem[1]);

/* Initialization of DECnet Session Control Port */
scp = DN_SK(sk);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 60b46f2a6896..91735d631a28 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -452,8 +452,8 @@ void tcp_init_sock(struct sock *sk)

icsk->icsk_sync_mss = tcp_sync_mss;

- WRITE_ONCE(sk->sk_sndbuf, sock_net(sk)->ipv4.sysctl_tcp_wmem[1]);
- WRITE_ONCE(sk->sk_rcvbuf, sock_net(sk)->ipv4.sysctl_tcp_rmem[1]);
+ WRITE_ONCE(sk->sk_sndbuf, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_wmem[1]));
+ WRITE_ONCE(sk->sk_rcvbuf, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[1]));

sk_sockets_allocated_inc(sk);
}
@@ -1743,7 +1743,7 @@ int tcp_set_rcvlowat(struct sock *sk, int val)
if (sk->sk_userlocks & SOCK_RCVBUF_LOCK)
cap = sk->sk_rcvbuf >> 1;
else
- cap = sock_net(sk)->ipv4.sysctl_tcp_rmem[2] >> 1;
+ cap = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2]) >> 1;
val = min(val, cap);
WRITE_ONCE(sk->sk_rcvlowat, val ? : 1);

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index de066fad7dfe..f09b1321a960 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -426,7 +426,7 @@ static void tcp_sndbuf_expand(struct sock *sk)

if (sk->sk_sndbuf < sndmem)
WRITE_ONCE(sk->sk_sndbuf,
- min(sndmem, sock_net(sk)->ipv4.sysctl_tcp_wmem[2]));
+ min(sndmem, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_wmem[2])));
}

/* 2. Tuning advertised window (window_clamp, rcv_ssthresh)
@@ -461,7 +461,7 @@ static int __tcp_grow_window(const struct sock *sk, const struct sk_buff *skb,
struct tcp_sock *tp = tcp_sk(sk);
/* Optimize this! */
int truesize = tcp_win_from_space(sk, skbtruesize) >> 1;
- int window = tcp_win_from_space(sk, sock_net(sk)->ipv4.sysctl_tcp_rmem[2]) >> 1;
+ int window = tcp_win_from_space(sk, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2])) >> 1;

while (tp->rcv_ssthresh <= window) {
if (truesize <= skb->len)
@@ -574,16 +574,17 @@ static void tcp_clamp_window(struct sock *sk)
struct tcp_sock *tp = tcp_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
struct net *net = sock_net(sk);
+ int rmem2;

icsk->icsk_ack.quick = 0;
+ rmem2 = READ_ONCE(net->ipv4.sysctl_tcp_rmem[2]);

- if (sk->sk_rcvbuf < net->ipv4.sysctl_tcp_rmem[2] &&
+ if (sk->sk_rcvbuf < rmem2 &&
!(sk->sk_userlocks & SOCK_RCVBUF_LOCK) &&
!tcp_under_memory_pressure(sk) &&
sk_memory_allocated(sk) < sk_prot_mem_limits(sk, 0)) {
WRITE_ONCE(sk->sk_rcvbuf,
- min(atomic_read(&sk->sk_rmem_alloc),
- net->ipv4.sysctl_tcp_rmem[2]));
+ min(atomic_read(&sk->sk_rmem_alloc), rmem2));
}
if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf)
tp->rcv_ssthresh = min(tp->window_clamp, 2U * tp->advmss);
@@ -745,7 +746,7 @@ void tcp_rcv_space_adjust(struct sock *sk)

do_div(rcvwin, tp->advmss);
rcvbuf = min_t(u64, rcvwin * rcvmem,
- sock_net(sk)->ipv4.sysctl_tcp_rmem[2]);
+ READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2]));
if (rcvbuf > sk->sk_rcvbuf) {
WRITE_ONCE(sk->sk_rcvbuf, rcvbuf);

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 60c9f7f444e0..66836b8bd46f 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -238,7 +238,7 @@ void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss,
*rcv_wscale = 0;
if (wscale_ok) {
/* Set window scaling on max possible window */
- space = max_t(u32, space, sock_net(sk)->ipv4.sysctl_tcp_rmem[2]);
+ space = max_t(u32, space, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2]));
space = max_t(u32, space, sysctl_rmem_max);
space = min_t(u32, space, *window_clamp);
*rcv_wscale = clamp_t(int, ilog2(space) - 15,
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index e2790a6e90fb..07b5a2044cab 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1900,7 +1900,7 @@ static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied)

do_div(rcvwin, advmss);
rcvbuf = min_t(u64, rcvwin * rcvmem,
- sock_net(sk)->ipv4.sysctl_tcp_rmem[2]);
+ READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2]));

if (rcvbuf > sk->sk_rcvbuf) {
u32 window_clamp;
@@ -2597,8 +2597,8 @@ static int mptcp_init_sock(struct sock *sk)
mptcp_ca_reset(sk);

sk_sockets_allocated_inc(sk);
- sk->sk_rcvbuf = sock_net(sk)->ipv4.sysctl_tcp_rmem[1];
- sk->sk_sndbuf = sock_net(sk)->ipv4.sysctl_tcp_wmem[1];
+ sk->sk_rcvbuf = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[1]);
+ sk->sk_sndbuf = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_wmem[1]);

return 0;
}
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 43509c7e90fc..f1c3b8eb4b3d 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -517,7 +517,7 @@ static int tipc_sk_create(struct net *net, struct socket *sock,
timer_setup(&sk->sk_timer, tipc_sk_timeout, 0);
sk->sk_shutdown = 0;
sk->sk_backlog_rcv = tipc_sk_backlog_rcv;
- sk->sk_rcvbuf = sysctl_tipc_rmem[1];
+ sk->sk_rcvbuf = READ_ONCE(sysctl_tipc_rmem[1]);
sk->sk_data_ready = tipc_data_ready;
sk->sk_write_space = tipc_write_space;
sk->sk_destruct = tipc_sock_destruct;
--
2.35.1