From nobody Wed Oct 8 02:22:22 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 0AA572F19B1; Thu, 3 Jul 2025 15:20:51 +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=1751556053; cv=none; b=Ww9Rw4asKWzrXlYK+OHsWCOcWrdKZDEvtEDXH583NlPFoCZbqNdtaEZ9tVFSZ3XjU90YqkMyYLEfZFOfKFo/MzTHnlDPV56VXkAz/O6JIMDCaYtZQouy+aPLkNq78xi+xMV2Cnq0ZjzjRNeiWkvf36ErYJbxj5fQMC2CEqbGusI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751556053; c=relaxed/simple; bh=SPx4SswMfMQBAfm8fETipBX6Qj2Yjr4qC+DMcHRsVjY=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=cM0T+yCx1LvQ278r+r1xyO9I4GVesdvfo+y4l6SUacgEOWkgzr0tMrwvvqXxhkm93SIZ9xrcdjAMZJ3Ak1IBdbPefdVFPHBqdKwAmTI2R3mlkfchiMhRbo+3ZQWkYOIf58hbSqCLw4dyH/9HugWYYSRJM1JCtE88XdpMPmeAV58= 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=ToXrVIA/; 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="ToXrVIA/" Received: from mailtransmit03.runbox ([10.9.9.163] 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 1uXLk0-000pKk-5w; Thu, 03 Jul 2025 17:20:48 +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=S2vuJXneksNDH90Lcc+wduKpDPpOL9tpBDgzk7O7Gto=; b=ToXrVIA/4BVe5vJKaJ9Lnq6Zq0 1rFNqTH2eb6B2BEpG/IHHwpPJobpebkcBiznmb+6Rbse117d5LhWAa+sJNH0nmEUKkNYnzSTdWquE Blpnj3Af/mnY5ZKmIdNBFdJt7S4GEaX8R7ljUdR2YzvYQOKng/pnrBUJMSgF2COYVYpCMrseMiyD+ W91L0cSgnsYg3jAnkMq8GNb3LesyAll4Xr5a/F7LC0Uh88bnJ8dGd4T1ar85ub/wBoFvq0WZCEX+c M2FD+Jrr6PFggrowGQNmAvrPp2h7hYH6P4EhVodp6rvppYArdhZyxTmI7hFl9Pl1RuPEhZaPexOPQ kM5phP8g==; Received: from [10.9.9.73] (helo=submission02.runbox) by mailtransmit03.runbox with esmtp (Exim 4.86_2) (envelope-from ) id 1uXLjo-0006fW-VP; Thu, 03 Jul 2025 17:20:37 +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 1uXLhk-001WIY-Hd; Thu, 03 Jul 2025 17:18:28 +0200 From: Michal Luczaj Date: Thu, 03 Jul 2025 17:18:19 +0200 Subject: [PATCH net v4 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: <20250703-vsock-transports-toctou-v4-2-98f0eb530747@rbox.co> References: <20250703-vsock-transports-toctou-v4-0-98f0eb530747@rbox.co> In-Reply-To: <20250703-vsock-transports-toctou-v4-0-98f0eb530747@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..66404c06bdaa0dc453a625c08a0= 4c7eb14a95498 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 away 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 2.50.0