From nobody Wed Oct 8 05:52:20 2025 Received: from mailtransmit04.runbox.com (mailtransmit04.runbox.com [185.226.149.37]) (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 ED81228983F for ; Wed, 2 Jul 2025 13:38:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.226.149.37 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751463538; cv=none; b=KaGTJEb08RWSXP1HffyhxzAUI76ILAySrXKeuz3oby9fqo4SgpTc8Se/pSNzagmMfPoxOC/kDKymxSXtG2GnwSXSA7iCVb957ATmVow6AE6ad71MAVIbceLH/vvio4YWmh0JxwY7Te6piGSY7XXcO+IJ5guyxmgOhwx1R6BNk2g= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751463538; c=relaxed/simple; bh=7oqwIalbg6zgFWyQYltaEI+okvEaE/eUEvw96Z3S2es=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Hv2z3NmLUxxsbFubTQSPqUAU/y1Dx5+kqc0X+RU5+cZjmtcl4uentBlcWhv4uIfPOc9WXqgEqYlFOvI3QQJfhanh0DbvoANV32MQtrCMZpYa2OTvUid4OfqKQ2k0KRHzCigVHYBah7XjbBzam8cRQ1G/YZzg1AV6buFB0ajehTo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rbox.co; spf=pass smtp.mailfrom=rbox.co; dkim=pass (2048-bit key) header.d=rbox.co header.i=@rbox.co header.b=twIQfRG8; arc=none smtp.client-ip=185.226.149.37 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rbox.co Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=rbox.co Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=rbox.co header.i=@rbox.co header.b="twIQfRG8" Received: from mailtransmit02.runbox ([10.9.9.162] helo=aibo.runbox.com) by mailtransmit04.runbox.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1uWxfr-00GcMe-2U; Wed, 02 Jul 2025 15:38:55 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=rbox.co; s=selector2; h=Cc:To:In-Reply-To:References:Message-Id: Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date:From; bh=3kxEmPLnragLTHLWVkSfmPayQlA6UO7668ntOUDzlyE=; b=twIQfRG8s6M9NII9XrArJJgjD0 DjrvGQxTkAbzPAWDVGTM51nyvveplh1sFFwCO/VUw4u7x8ooJtp4xPmAKLTlam/aDa9yWf/55iPmy jxkfMZ+hwGY8BZQmJ9lPGnvgIKs8tV6dD23QdbvKy7KzHsDJh0N5S10suj90S+CUQ2m/W2oMlOHWg DODZIcPZbmkhl9ATjxt3L1vcXk98MnQcSx/MvEOcDk9K4hdaIy9usWI1f7EExp5btaMsh3qrn629+ 4L1tw4gU7UqQawbaxJFdUtqvreEm5G6PFXkW0CF3f9F8DHN4D/AfN5BhjTugx6kRhtj7nIl8C/PDz 0vpH4ZVg==; Received: from [10.9.9.73] (helo=submission02.runbox) by mailtransmit02.runbox with esmtp (Exim 4.86_2) (envelope-from ) id 1uWxfq-0006FY-NM; Wed, 02 Jul 2025 15:38:54 +0200 Received: by submission02.runbox with esmtpsa [Authenticated ID (604044)] (TLS1.2:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.93) id 1uWxfm-009LQl-Oc; Wed, 02 Jul 2025 15:38:50 +0200 From: Michal Luczaj Date: Wed, 02 Jul 2025 15:38:44 +0200 Subject: [PATCH net v3 2/3] vsock: Fix transport_* TOCTOU Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250702-vsock-transports-toctou-v3-2-0a7e2e692987@rbox.co> References: <20250702-vsock-transports-toctou-v3-0-0a7e2e692987@rbox.co> In-Reply-To: <20250702-vsock-transports-toctou-v3-0-0a7e2e692987@rbox.co> To: Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Stefan Hajnoczi Cc: virtualization@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Michal Luczaj X-Mailer: b4 0.14.2 Transport assignment may race with module unload. Protect new_transport from becoming a stale pointer. This also takes care of an insecure call in vsock_use_local_transport(); add a lockdep assert. BUG: unable to handle page fault for address: fffffbfff8056000 Oops: Oops: 0000 [#1] SMP KASAN RIP: 0010:vsock_assign_transport+0x366/0x600 Call Trace: vsock_connect+0x59c/0xc40 __sys_connect+0xe8/0x100 __x64_sys_connect+0x6e/0xc0 do_syscall_64+0x92/0x1c0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Fixes: c0cfa2d8a788 ("vsock: add multi-transports support") Reviewed-by: Stefano Garzarella Signed-off-by: Michal Luczaj --- net/vmw_vsock/af_vsock.c | 28 +++++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index 39473b9e0829f240045262aef00cbae82a425dcc..9b2af5c63f7c2ae575c160415bd= 77208a3980835 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -407,6 +407,8 @@ EXPORT_SYMBOL_GPL(vsock_enqueue_accept); =20 static bool vsock_use_local_transport(unsigned int remote_cid) { + lockdep_assert_held(&vsock_register_mutex); + if (!transport_local) return false; =20 @@ -464,6 +466,8 @@ int vsock_assign_transport(struct vsock_sock *vsk, stru= ct vsock_sock *psk) =20 remote_flags =3D vsk->remote_addr.svm_flags; =20 + mutex_lock(&vsock_register_mutex); + switch (sk->sk_type) { case SOCK_DGRAM: new_transport =3D transport_dgram; @@ -479,12 +483,15 @@ int vsock_assign_transport(struct vsock_sock *vsk, st= ruct vsock_sock *psk) new_transport =3D transport_h2g; break; default: - return -ESOCKTNOSUPPORT; + ret =3D -ESOCKTNOSUPPORT; + goto err; } =20 if (vsk->transport) { - if (vsk->transport =3D=3D new_transport) - return 0; + if (vsk->transport =3D=3D new_transport) { + ret =3D 0; + goto err; + } =20 /* transport->release() must be called with sock lock acquired. * This path can only be taken during vsock_connect(), where we @@ -508,8 +515,16 @@ int vsock_assign_transport(struct vsock_sock *vsk, str= uct vsock_sock *psk) /* We increase the module refcnt to prevent the transport unloading * while there are open sockets assigned to it. */ - if (!new_transport || !try_module_get(new_transport->module)) - return -ENODEV; + if (!new_transport || !try_module_get(new_transport->module)) { + ret =3D -ENODEV; + goto err; + } + + /* It's safe to release the mutex after a successful try_module_get(). + * Whichever transport `new_transport` points at, it won't go await + * until the last module_put() below or in vsock_deassign_transport(). + */ + mutex_unlock(&vsock_register_mutex); =20 if (sk->sk_type =3D=3D SOCK_SEQPACKET) { if (!new_transport->seqpacket_allow || @@ -528,6 +543,9 @@ int vsock_assign_transport(struct vsock_sock *vsk, stru= ct vsock_sock *psk) vsk->transport =3D new_transport; =20 return 0; +err: + mutex_unlock(&vsock_register_mutex); + return ret; } EXPORT_SYMBOL_GPL(vsock_assign_transport); =20 --=20 2.49.0