From patchwork Tue Jan 5 22:06:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Wysochanski X-Patchwork-Id: 12000371 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A40AC43333 for ; Tue, 5 Jan 2021 22:08:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DE766207AB for ; Tue, 5 Jan 2021 22:08:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731579AbhAEWIF (ORCPT ); Tue, 5 Jan 2021 17:08:05 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:51284 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731696AbhAEWIE (ORCPT ); Tue, 5 Jan 2021 17:08:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1609884397; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/FGLtQrM2gbMoWYy90TwZj98DcwKI8Nzc/wMX93YjHs=; b=fSy2J4vKJFVyll6IjJsfhsmFPydn5WQwwEbZvYVmVpl9Xtup4rCmbC2ydM/I/m+CWTjCK8 7+is6m0q/K3uGbxqdmor6/BZ+ZEYgN0faPWHy+rHlCbGhSWDRdQ0LA/DE7Ba1UCqqnOQiA 1l5m38/ie/6St+uFsiDhuRe9g9QAqjA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-373-WVW436W-NPyC7c7pyaX7Ew-1; Tue, 05 Jan 2021 17:06:36 -0500 X-MC-Unique: WVW436W-NPyC7c7pyaX7Ew-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 64D5D1800D41 for ; Tue, 5 Jan 2021 22:06:35 +0000 (UTC) Received: from f31-node1.dwysocha.net (dhcp145-42.rdu.redhat.com [10.13.145.42]) by smtp.corp.redhat.com (Postfix) with ESMTP id 33684271A9 for ; Tue, 5 Jan 2021 22:06:35 +0000 (UTC) From: Dave Wysochanski To: linux-nfs@vger.kernel.org Subject: [PATCH 2/2] SUNRPC: Handle 0 length opaque XDR object data properly Date: Tue, 5 Jan 2021 17:06:34 -0500 Message-Id: <20210105220634.27910-3-dwysocha@redhat.com> In-Reply-To: <20210105220634.27910-1-dwysocha@redhat.com> References: <20210105220634.27910-1-dwysocha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org When handling an auth_gss downcall, it's possible to get 0-length opaque object for the acceptor. In this case we should make sure simple_get_netobj() returns -EFAULT and does not continue to kmemdup() which will return a special pointer value of ZERO_SIZE_PTR. If it just so happens that the rpcgss_context trace event is enabled, the kernel will crash as follows: [ 162.887992] BUG: kernel NULL pointer dereference, address: 0000000000000010 [ 162.898693] #PF: supervisor read access in kernel mode [ 162.900830] #PF: error_code(0x0000) - not-present page [ 162.902940] PGD 0 P4D 0 [ 162.904027] Oops: 0000 [#1] SMP PTI [ 162.905493] CPU: 4 PID: 4321 Comm: rpc.gssd Kdump: loaded Not tainted 5.10.0 #133 [ 162.908548] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 [ 162.910978] RIP: 0010:strlen+0x0/0x20 [ 162.912505] Code: 48 89 f9 74 09 48 83 c1 01 80 39 00 75 f7 31 d2 44 0f b6 04 16 44 88 04 11 48 83 c2 01 45 84 c0 75 ee c3 0f 1f 80 00 00 00 00 <80> 3f 00 74 10 48 89 f8 48 83 c0 01 80 38 00 75 f7 48 29 f8 c3 31 [ 162.920101] RSP: 0018:ffffaec900c77d90 EFLAGS: 00010202 [ 162.922263] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000fffde697 [ 162.925158] RDX: 000000000000002f RSI: 0000000000000080 RDI: 0000000000000010 [ 162.928073] RBP: 0000000000000010 R08: 0000000000000e10 R09: 0000000000000000 [ 162.930976] R10: ffff8e698a590cb8 R11: 0000000000000001 R12: 0000000000000e10 [ 162.933883] R13: 00000000fffde697 R14: 000000010034d517 R15: 0000000000070028 [ 162.936777] FS: 00007f1e1eb93700(0000) GS:ffff8e6ab7d00000(0000) knlGS:0000000000000000 [ 162.940067] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 162.942417] CR2: 0000000000000010 CR3: 0000000104eba000 CR4: 00000000000406e0 [ 162.945300] Call Trace: [ 162.946428] trace_event_raw_event_rpcgss_context+0x84/0x140 [auth_rpcgss] [ 162.949308] ? __kmalloc_track_caller+0x35/0x5a0 [ 162.951224] ? gss_pipe_downcall+0x3a3/0x6a0 [auth_rpcgss] [ 162.953484] gss_pipe_downcall+0x585/0x6a0 [auth_rpcgss] [ 162.955953] rpc_pipe_write+0x58/0x70 [sunrpc] [ 162.957849] vfs_write+0xcb/0x2c0 [ 162.959264] ksys_write+0x68/0xe0 [ 162.960706] do_syscall_64+0x33/0x40 [ 162.962238] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 162.964346] RIP: 0033:0x7f1e1f1e57df Signed-off-by: Dave Wysochanski --- include/linux/sunrpc/xdr.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h index 8ef788ff80b9..aca38bdb0059 100644 --- a/include/linux/sunrpc/xdr.h +++ b/include/linux/sunrpc/xdr.h @@ -53,7 +53,7 @@ simple_get_netobj(const void *p, const void *end, struct xdr_netobj *dest) if (IS_ERR(p)) return p; q = (const void *)((const char *)p + len); - if (unlikely(q > end || q < p)) + if (unlikely(q > end || q <= p)) return ERR_PTR(-EFAULT); dest->data = kmemdup(p, len, GFP_NOFS); if (unlikely(dest->data == NULL))