| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.12 024/161] mptcp: fix sk_forward_memory corruption on retransmission | Date | Tue, 8 Jun 2021 20:25:54 +0200 |
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From: Paolo Abeni <pabeni@redhat.com>
[ Upstream commit b5941f066b4ca331db225a976dae1d6ca8cf0ae3 ]
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()
Several helpers in __mptcp_clean_una_wakeup() will update sk_forward_alloc, possibly causing such field corruption, as reported by Matthieu.
Address the issue providing and using a new variant of blamed function which explicitly acquires the msk spin lock.
Fixes: 64b9cea7a0af ("mptcp: fix spurious retransmissions") Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/172 Reported-by: Matthieu Baerts <matthieu.baerts@tessares.net> Tested-by: Matthieu Baerts <matthieu.baerts@tessares.net> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> --- net/mptcp/protocol.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 228dd40828c4..225b98821517 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -937,6 +937,10 @@ 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; @@ -1075,10 +1079,20 @@ out: static void __mptcp_clean_una_wakeup(struct sock *sk) { +#ifdef CONFIG_LOCKDEP + WARN_ON_ONCE(!lockdep_is_held(&sk->sk_lock.slock)); +#endif __mptcp_clean_una(sk); mptcp_write_space(sk); } +static void mptcp_clean_una_wakeup(struct sock *sk) +{ + mptcp_data_lock(sk); + __mptcp_clean_una_wakeup(sk); + mptcp_data_unlock(sk); +} + static void mptcp_enter_memory_pressure(struct sock *sk) { struct mptcp_subflow_context *subflow; @@ -2288,7 +2302,7 @@ 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)) { -- 2.30.2
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