From: Paolo Abeni <pabeni@redhat.com>
To: MPTCP Upstream <mptcp@lists.linux.dev>
Subject: [PATCH mptcp-net] mptcp: fix sk_forward_memory corruption under memory pressure
Date: Fri, 14 May 2021 12:05:45 +0200 [thread overview]
Message-ID: <b84d11a2f4c33e69637567e64138a453611064dc.1620986525.git.pabeni@redhat.com> (raw)
MPTCP sk_forward_memory handling is a bit special, as such field
is protected by the msk socket spin_lock, instead of the plain
socket lock.
Currently we have a code path updating such field without handling
the relevant lock:
__mptcp_retrans() -> __mptcp_clean_una_wakeup() -> __mptcp_update_wmem()
We can hit the above only under memory pressure. When that happen,
forward memory accounting could be corrupted, as reported by Mat.
Address the issue creating a new variant of __mptcp_clean_una_wakeup()
which handle fwd memory updates with the proper care and invoking
such new helper in the relevant code path.
Reported-by: 'Matthieu Baerts <matthieu.baerts@tessares.net>'
Fixes: 64b9cea7a0af ("mptcp: fix spurious retransmissions")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
net/mptcp/protocol.c | 36 ++++++++++++++++++++++++++++--------
1 file changed, 28 insertions(+), 8 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 2d21a4793d9d..1d5d451e9211 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -947,6 +947,10 @@ static void __mptcp_update_wmem(struct sock *sk)
{
struct mptcp_sock *msk = mptcp_sk(sk);
+#ifdef CONFIG_LOCKDEP
+ WARN_ON_ONCE(!lockdep_is_held(&sk->sk_lock.slock));
+#endif
+
if (!msk->wmem_reserved)
return;
@@ -1027,7 +1031,7 @@ static void dfrag_clear(struct sock *sk, struct mptcp_data_frag *dfrag)
put_page(dfrag->page);
}
-static void __mptcp_clean_una(struct sock *sk)
+static bool __mptcp_do_clean_una(struct sock *sk)
{
struct mptcp_sock *msk = mptcp_sk(sk);
struct mptcp_data_frag *dtmp, *dfrag;
@@ -1068,12 +1072,6 @@ static void __mptcp_clean_una(struct sock *sk)
}
out:
- if (cleaned) {
- if (tcp_under_memory_pressure(sk)) {
- __mptcp_update_wmem(sk);
- sk_mem_reclaim_partial(sk);
- }
- }
if (snd_una == READ_ONCE(msk->snd_nxt)) {
if (msk->timer_ival && !mptcp_data_fin_enabled(msk))
@@ -1081,6 +1079,15 @@ static void __mptcp_clean_una(struct sock *sk)
} else {
mptcp_reset_timer(sk);
}
+ return cleaned;
+}
+
+static void __mptcp_clean_una(struct sock *sk)
+{
+ if (__mptcp_do_clean_una(sk) && tcp_under_memory_pressure(sk)) {
+ __mptcp_update_wmem(sk);
+ sk_mem_reclaim_partial(sk);
+ }
}
static void __mptcp_clean_una_wakeup(struct sock *sk)
@@ -1089,6 +1096,19 @@ static void __mptcp_clean_una_wakeup(struct sock *sk)
mptcp_write_space(sk);
}
+/* variant __mptcp_clean_una_wakeup() for caller owning the msk socket lock,
+ * but not the msk_data_lock/msk socket spin lock
+ */
+static void mptcp_clean_una_wakeup(struct sock *sk)
+{
+#ifdef CONFIG_LOCKDEP
+ WARN_ON_ONCE(!lockdep_is_held(&sk->sk_lock));
+#endif
+ if (__mptcp_do_clean_una(sk) && tcp_under_memory_pressure(sk))
+ mptcp_mem_reclaim_partial(sk);
+ mptcp_write_space(sk);
+}
+
static void mptcp_enter_memory_pressure(struct sock *sk)
{
struct mptcp_subflow_context *subflow;
@@ -2299,7 +2319,7 @@ static void __mptcp_retrans(struct sock *sk)
struct sock *ssk;
int ret;
- __mptcp_clean_una_wakeup(sk);
+ mptcp_clean_una_wakeup(sk);
dfrag = mptcp_rtx_head(sk);
if (!dfrag) {
if (mptcp_data_fin_enabled(msk)) {
--
2.26.3
next reply other threads:[~2021-05-14 10:05 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-14 10:05 Paolo Abeni [this message]
2021-05-14 21:44 ` [PATCH mptcp-net] mptcp: fix sk_forward_memory corruption under memory pressure Mat Martineau
2021-05-17 19:15 ` Matthieu Baerts
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