From: Paolo Abeni Date: Mon, 3 Aug 2026 16:16:40 +0000 (+0200) Subject: mptcp: reclaim forward-allocated memory on RX path errors X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=41b49a8b914ec7dcb03eae93fb27f3c464078644;p=thirdparty%2Fkernel%2Flinux.git mptcp: reclaim forward-allocated memory on RX path errors After commit 9db5b3cec4ec ("mptcp: borrow forward memory from subflow"), errors in the receive path prior to queueing skbs into the receive queue do not trigger forward-allocated memory reclaiming. Prevent forward memory from growing unboundedly in pathological drop scenarios by explicitly reclaiming memory when skbs are dropped. Fixes: 9db5b3cec4ec ("mptcp: borrow forward memory from subflow") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260803-net-mptcp-misc-fixes-7-2-rc6-v2-8-b8f496d71664@kernel.org Signed-off-by: Jakub Kicinski --- diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index ca644ec53eed..7c8180d8d5ef 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -149,6 +149,12 @@ struct sock *__mptcp_nmpc_sk(struct mptcp_sock *msk) static void mptcp_drop(struct sock *sk, struct sk_buff *skb) { + /* The skb forward memory was already transferred to sk by + * mptcp_borrow_fwdmem(), even before setting the destructor. + */ + if (!skb->destructor) + sk_mem_reclaim(sk); + sk_drops_skbadd(sk, skb); __kfree_skb(skb); }