From nobody Mon Sep 21 15:57:07 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 38654392C48; Mon, 3 Aug 2026 16:17:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785773835; cv=none; b=ID6sQ1P0VJ9ULOOb0kTJPRPFg5+wxWaRo8DS+mqM/CAvTFb0o2zsig8lVuMAef/YVqrwWjR+VC31K7Sju3jhXFSItQnblrxkim8vCPuZ+uoDC1C2LQNh0+ToKEQqrGX6YTY5k/GU+WYPyp4Pq7j3AiSXwI8OayucS1NMXdfI8Wc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785773835; c=relaxed/simple; bh=xnqFISoqTLMCerUD5c4zSjTlfN+SKMko6NaQaLus8dk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=NOuNXR4itO1uJYsoa1H4qeebb0LQ7BZ048fCkKvB3qlN9d61MrfB8EJwdPl+YJtOExRvphdDQM+tzpU5zJ66LGdOAG3gHcLNiN21Z/F5+NJkACHKhkrfcF84kQRTP3fo+dAL5hK9UG/lcYtrwYN7zIV+iQ9ASDs6y7T2AEOnzbo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NyHYZb8S; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NyHYZb8S" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 748551F000E9; Mon, 3 Aug 2026 16:17:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785773833; bh=j4Eph3k7INwhaL5Gv4jnG9wsbDawQ3A4kZn6N6ISjdc=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=NyHYZb8SvWK3YIZFKUCqRZjaTsIrlePTuMXayKGAo2k5FOYmCO/vbsIvElTEXuk+5 m5hpZdV57Q+sjEcSXbgfxTYMnPIVYeqPQDedEo43s0PKGr2sTiMUFToixMb+gi7Nza r4fwSdfQqlcBv0lPZc5Kdluq3Yyjq75ofWfmZlz4GNDRIIIky1U8VbayQzGEwN0k00 S/rCCoQA5GW5qSBFvUJl18ii1Skz5P2x0NZKhfHrYCTtazN4sUjhOsQrbwoCuBUGqp b9/7CKLIjS60Ocmax4z0epsR7yYym7Hbzw2Fyhk39gQuSoZadNCBsV6ae+GVIotB0F 9LEzMcVRgKTdg== From: "Matthieu Baerts (NGI0)" Date: Mon, 03 Aug 2026 18:16:38 +0200 Subject: [PATCH net v2 6/8] mptcp: pm: fix memory leak from alloc-during-teardown race Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260803-net-mptcp-misc-fixes-7-2-rc6-v2-6-b8f496d71664@kernel.org> References: <20260803-net-mptcp-misc-fixes-7-2-rc6-v2-0-b8f496d71664@kernel.org> In-Reply-To: <20260803-net-mptcp-misc-fixes-7-2-rc6-v2-0-b8f496d71664@kernel.org> To: Mat Martineau , Geliang Tang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman Cc: netdev@vger.kernel.org, mptcp@lists.linux.dev, linux-kernel@vger.kernel.org, "Matthieu Baerts (NGI0)" , Shardul Bankar , stable@vger.kernel.org, Kishen Maloor X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=4572; i=matttbe@kernel.org; h=from:subject:message-id; bh=HhsABg2acSkM/Qyo/cPU//Pg2lIC3VAwQp0iPEbLdOk=; b=owGbwMvMwCVWo/Th0Gd3rumMp9WSGLIK9n2aOj/85pGZdX8M5N42T9TIVdloHVWpkdnPbaXBG //18ZWLHaUsDGJcDLJiiizSbZH5M59X8ZZ4+VnAzGFlAhnCwMUpABNZHszI8PrHNJs56seVs+4s +2Bvy7dF3LvlX5RPkuWJtWzNR9iS2Rn+cLvZL31eOi2pL/qLcGem6U4j9oPbt0WItX5cUG/i8E2 ZFQA= X-Developer-Key: i=matttbe@kernel.org; a=openpgp; fpr=E8CB85F76877057A6E27F77AF6B7824F4269A073 From: Shardul Bankar mptcp_pm_destroy() empties msk->pm.anno_list and msk->pm.userspace_pm_local_addr_list under msk->pm.lock during socket teardown, dropping the lock between the two. A concurrent userspace PM genl ANNOUNCE on the same msk holds a sock reference via mptcp_token_get_sock() and, in mptcp_pm_nl_announce_doit(), calls mptcp_userspace_pm_append_new_local_addr() and mptcp_pm_announced_alloc(). Both take msk->pm.lock briefly to add to their respective lists. Because the genl handler holds a sock reference, mptcp_pm_destroy() may run on the same msk via mptcp_disconnect(), which invokes mptcp_destroy_common() without dropping the sock refcount, before the handler completes. If the lock acquisitions interleave such that mptcp_pm_destroy() empties a list first, the later alloc adds its entry to a list head that nothing else iterates for this msk, and the entry leaks. kmemleak reports both mptcp_pm_add_addr objects (from mptcp_pm_announced_alloc()) and mptcp_pm_addr_entry objects (from mptcp_userspace_pm_append_new_local_addr()) under sustained concurrent ANNOUNCE + close load against the userspace PM. Add an MPTCP_PM_DESTROYING bit in msk->pm.status, set by mptcp_pm_destroy() under pm.lock before the lists are emptied and checked under pm.lock by the alloc paths. Either the alloc takes pm.lock first, in which case its entry is on the list when mptcp_pm_destroy() frees it; or mptcp_pm_destroy() takes pm.lock first, in which case the later alloc observes the bit and refuses. Found by an MPTCP protocol-flow harness extending BRF (arXiv:2305.08782). Fixes: 9ab4807c84a4 ("mptcp: netlink: Add MPTCP_PM_CMD_ANNOUNCE") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Shardul Bankar Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) --- Cc: Kishen Maloor v2: New. --- net/mptcp/pm.c | 13 +++++++++++-- net/mptcp/pm_userspace.c | 4 ++++ net/mptcp/protocol.h | 7 ++++--- 3 files changed, 19 insertions(+), 5 deletions(-) diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c index c71dcf887683..64a1236aabee 100644 --- a/net/mptcp/pm.c +++ b/net/mptcp/pm.c @@ -443,6 +443,9 @@ bool mptcp_pm_announced_alloc(struct mptcp_sock *msk, =20 lockdep_assert_held(&msk->pm.lock); =20 + if (msk->pm.status & BIT(MPTCP_PM_DESTROYING)) + return false; + add_entry =3D mptcp_pm_announced_lookup(msk, addr); if (add_entry) { if (WARN_ON_ONCE(mptcp_pm_is_kernel(msk))) @@ -1145,10 +1148,16 @@ void mptcp_pm_worker(struct mptcp_sock *msk) =20 void mptcp_pm_destroy(struct mptcp_sock *msk) { + spin_lock_bh(&msk->pm.lock); + msk->pm.status |=3D BIT(MPTCP_PM_DESTROYING); + spin_unlock_bh(&msk->pm.lock); + mptcp_pm_free_announced_list(msk); =20 - if (mptcp_pm_is_userspace(msk)) - mptcp_userspace_pm_free_local_addr_list(msk); + /* Free the userspace local address list unconditionally: the socket + * can be reused (mptcp_disconnect()) and re-selected to a different PM + */ + mptcp_userspace_pm_free_local_addr_list(msk); } =20 void mptcp_pm_data_reset(struct mptcp_sock *msk) diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c index 945aa5afc2dd..2203cc2d2748 100644 --- a/net/mptcp/pm_userspace.c +++ b/net/mptcp/pm_userspace.c @@ -54,6 +54,10 @@ static int mptcp_userspace_pm_append_new_local_addr(stru= ct mptcp_sock *msk, bitmap_zero(id_bitmap, MPTCP_PM_MAX_ADDR_ID + 1); =20 spin_lock_bh(&msk->pm.lock); + if (msk->pm.status & BIT(MPTCP_PM_DESTROYING)) { + ret =3D -EINVAL; + goto append_err; + } mptcp_for_each_userspace_pm_addr(msk, e) { addr_match =3D mptcp_addresses_equal(&e->addr, &entry->addr, true); if (addr_match && entry->addr.id =3D=3D 0 && needs_id) diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index c13680d18994..1b80f2d6ec5a 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -190,9 +190,10 @@ enum mptcp_pm_status { MPTCP_PM_ESTABLISHED, MPTCP_PM_SUBFLOW_ESTABLISHED, MPTCP_PM_ALREADY_ESTABLISHED, /* persistent status, set after ESTABLISHED= event */ - MPTCP_PM_MPC_ENDPOINT_ACCOUNTED /* persistent status, set after MPC local= address is - * accounted int id_avail_bitmap - */ + MPTCP_PM_MPC_ENDPOINT_ACCOUNTED, /* persistent status, set after MPC loca= l address is + * accounted int id_avail_bitmap + */ + MPTCP_PM_DESTROYING, /* To fence out PM list allocs */ }; =20 enum mptcp_pm_type { --=20 2.53.0