From mboxrd@z Thu Jan 1 00:00:00 1970 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 C757FC433ED for ; Thu, 6 May 2021 16:12:46 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4DE9D61059 for ; Thu, 6 May 2021 16:12:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4DE9D61059 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.123645.233257 (Exim 4.92) (envelope-from ) id 1legc3-0005OO-Gr; Thu, 06 May 2021 16:12:31 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 123645.233257; Thu, 06 May 2021 16:12:31 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1legc3-0005OH-Dx; Thu, 06 May 2021 16:12:31 +0000 Received: by outflank-mailman (input) for mailman id 123645; Thu, 06 May 2021 16:12:30 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1legc2-0005OB-0i for xen-devel@lists.xenproject.org; Thu, 06 May 2021 16:12:30 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1legc0-00047q-M1; Thu, 06 May 2021 16:12:28 +0000 Received: from 54-240-197-235.amazon.com ([54.240.197.235] helo=ufe34d9ed68d054.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1legc0-0003uf-CI; Thu, 06 May 2021 16:12:28 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Message-Id:Date:Subject:Cc:To:From; bh=taAzfylmniFMr/i/NXbHSTg9722Z1jzHz8t2M1whrOw=; b=oCuBi89tY6Ij+vI5tcKSZ8QzwJ 1UnmlL6irFx2hokVbNHwE2Zk90srkcMDTeU+psg8ahVFfoPe9HhAAS8upaC7pycbdZy2SE+FFudPj vh1nvce0sNobV9xpb7SsTICO6UN0e2Yg+BFrTIygsZmQ8dB4mgNBGp4aaGHw28Jrj644=; From: Julien Grall To: xen-devel@lists.xenproject.org Cc: julien@xen.org, Julien Grall , Ian Jackson , Wei Liu , Juergen Gross Subject: [PATCH] tools/xenstored: Prevent a buffer overflow in dump_state_node_perms() Date: Thu, 6 May 2021 17:12:23 +0100 Message-Id: <20210506161223.15984-1-julien@xen.org> X-Mailer: git-send-email 2.17.1 From: Julien Grall ASAN reported one issue when Live Updating Xenstored: ================================================================= ==873==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffc194f53e0 at pc 0x555c6b323292 bp 0x7ffc194f5340 sp 0x7ffc194f5338 WRITE of size 1 at 0x7ffc194f53e0 thread T0 #0 0x555c6b323291 in dump_state_node_perms xen/tools/xenstore/xenstored_core.c:2468 #1 0x555c6b32746e in dump_state_special_node xen/tools/xenstore/xenstored_domain.c:1257 #2 0x555c6b32a702 in dump_state_special_nodes xen/tools/xenstore/xenstored_domain.c:1273 #3 0x555c6b32ddb3 in lu_dump_state xen/tools/xenstore/xenstored_control.c:521 #4 0x555c6b32e380 in do_lu_start xen/tools/xenstore/xenstored_control.c:660 #5 0x555c6b31b461 in call_delayed xen/tools/xenstore/xenstored_core.c:278 #6 0x555c6b32275e in main xen/tools/xenstore/xenstored_core.c:2357 #7 0x7f95eecf3d09 in __libc_start_main ../csu/libc-start.c:308 #8 0x555c6b3197e9 in _start (/usr/local/sbin/xenstored+0xc7e9) Address 0x7ffc194f53e0 is located in stack of thread T0 at offset 80 in frame #0 0x555c6b32713e in dump_state_special_node xen/tools/xenstore/xenstored_domain.c:1232 This frame has 2 object(s): [32, 40) 'head' (line 1233) [64, 80) 'sn' (line 1234) <== Memory access at offset 80 overflows this variable This is happening because the callers are passing a pointer to a variable allocated on the stack. However, the field perms is a dynamic array, so Xenstored will end up to read outside of the variable. Rework the code so the permissions are written one by one in the fd. Fixes: ed6eebf17d2c ("tools/xenstore: dump the xenstore state for live update") Signed-off-by: Julien Grall --- tools/xenstore/xenstored_core.c | 26 ++++++++++++++------------ tools/xenstore/xenstored_core.h | 3 +-- tools/xenstore/xenstored_domain.c | 2 +- 3 files changed, 16 insertions(+), 15 deletions(-) diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c index d54a6042a9f7..f68da12b5b23 100644 --- a/tools/xenstore/xenstored_core.c +++ b/tools/xenstore/xenstored_core.c @@ -2447,34 +2447,36 @@ const char *dump_state_buffered_data(FILE *fp, const struct connection *c, return NULL; } -const char *dump_state_node_perms(FILE *fp, struct xs_state_node *sn, - const struct xs_permissions *perms, +const char *dump_state_node_perms(FILE *fp, const struct xs_permissions *perms, unsigned int n_perms) { unsigned int p; for (p = 0; p < n_perms; p++) { + struct xs_state_node_perm sp; + switch ((int)perms[p].perms & ~XS_PERM_IGNORE) { case XS_PERM_READ: - sn->perms[p].access = XS_STATE_NODE_PERM_READ; + sp.access = XS_STATE_NODE_PERM_READ; break; case XS_PERM_WRITE: - sn->perms[p].access = XS_STATE_NODE_PERM_WRITE; + sp.access = XS_STATE_NODE_PERM_WRITE; break; case XS_PERM_READ | XS_PERM_WRITE: - sn->perms[p].access = XS_STATE_NODE_PERM_BOTH; + sp.access = XS_STATE_NODE_PERM_BOTH; break; default: - sn->perms[p].access = XS_STATE_NODE_PERM_NONE; + sp.access = XS_STATE_NODE_PERM_NONE; break; } - sn->perms[p].flags = (perms[p].perms & XS_PERM_IGNORE) + sp.flags = (perms[p].perms & XS_PERM_IGNORE) ? XS_STATE_NODE_PERM_IGNORE : 0; - sn->perms[p].domid = perms[p].id; - } + sp.domid = perms[p].id; - if (fwrite(sn->perms, sizeof(*sn->perms), n_perms, fp) != n_perms) - return "Dump node permissions error"; + if (fwrite(&sp, sizeof(sp), 1, fp) != 1) + return "Dump node permission error"; + + } return NULL; } @@ -2519,7 +2521,7 @@ static const char *dump_state_node_tree(FILE *fp, char *path) if (fwrite(&sn, sizeof(sn), 1, fp) != 1) return "Dump node state error"; - ret = dump_state_node_perms(fp, &sn, hdr->perms, hdr->num_perms); + ret = dump_state_node_perms(fp, hdr->perms, hdr->num_perms); if (ret) return ret; diff --git a/tools/xenstore/xenstored_core.h b/tools/xenstore/xenstored_core.h index 1cdbc3dcb5f7..b50ea3f57d5a 100644 --- a/tools/xenstore/xenstored_core.h +++ b/tools/xenstore/xenstored_core.h @@ -271,8 +271,7 @@ const char *dump_state_buffered_data(FILE *fp, const struct connection *c, const struct connection *conn, struct xs_state_connection *sc); const char *dump_state_nodes(FILE *fp, const void *ctx); -const char *dump_state_node_perms(FILE *fp, struct xs_state_node *sn, - const struct xs_permissions *perms, +const char *dump_state_node_perms(FILE *fp, const struct xs_permissions *perms, unsigned int n_perms); void read_state_global(const void *ctx, const void *state); diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c index 3d4d0649a243..580ed454a3f5 100644 --- a/tools/xenstore/xenstored_domain.c +++ b/tools/xenstore/xenstored_domain.c @@ -1254,7 +1254,7 @@ static const char *dump_state_special_node(FILE *fp, const char *name, if (fwrite(&sn, sizeof(sn), 1, fp) != 1) return "Dump special node error"; - ret = dump_state_node_perms(fp, &sn, perms->p, perms->num); + ret = dump_state_node_perms(fp, perms->p, perms->num); if (ret) return ret; -- 2.17.1