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Message-Id: <20220504014440.3697851-2-keescook@chromium.org>
Date: Tue, 3 May 2022 18:44:10 -0700
From: Kees Cook <keescook@...omium.org>
To: "Gustavo A . R . Silva" <gustavoars@...nel.org>
Cc: Kees Cook <keescook@...omium.org>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Rich Felker <dalias@...ifal.cx>,
Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org,
Alexei Starovoitov <ast@...nel.org>,
alsa-devel@...a-project.org, Al Viro <viro@...iv.linux.org.uk>,
Andrew Gabbasov <andrew_gabbasov@...tor.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Andy Gross <agross@...nel.org>,
Andy Lavr <andy.lavr@...il.com>,
Arend van Spriel <aspriel@...il.com>,
Baowen Zheng <baowen.zheng@...igine.com>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Bradley Grove <linuxdrivers@...otech.com>,
brcm80211-dev-list.pdl@...adcom.com,
Christian Brauner <brauner@...nel.org>,
Christian Göttsche <cgzones@...glemail.com>,
Christian Lamparter <chunkeey@...glemail.com>,
Chris Zankel <chris@...kel.net>,
Cong Wang <cong.wang@...edance.com>,
Daniel Axtens <dja@...ens.net>,
Daniel Vetter <daniel.vetter@...ll.ch>,
Dan Williams <dan.j.williams@...el.com>,
David Gow <davidgow@...gle.com>,
David Howells <dhowells@...hat.com>,
Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>,
devicetree@...r.kernel.org, Dexuan Cui <decui@...rosoft.com>,
Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
Eli Cohen <elic@...dia.com>,
Eric Paris <eparis@...isplace.org>,
Eugeniu Rosca <erosca@...adit-jv.com>,
Felipe Balbi <balbi@...nel.org>,
Francis Laniel <laniel_francis@...vacyrequired.com>,
Frank Rowand <frowand.list@...il.com>,
Franky Lin <franky.lin@...adcom.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Gregory Greenman <gregory.greenman@...el.com>,
Guenter Roeck <linux@...ck-us.net>,
Haiyang Zhang <haiyangz@...rosoft.com>,
Hante Meuleman <hante.meuleman@...adcom.com>,
Herbert Xu <herbert@...dor.apana.org.au>,
Hulk Robot <hulkci@...wei.com>,
"James E.J. Bottomley" <jejb@...ux.ibm.com>,
James Morris <jmorris@...ei.org>,
Jarkko Sakkinen <jarkko@...nel.org>,
Jaroslav Kysela <perex@...ex.cz>,
Jason Gunthorpe <jgg@...pe.ca>, Jens Axboe <axboe@...nel.dk>,
Johan Hedberg <johan.hedberg@...il.com>,
Johannes Berg <johannes.berg@...el.com>,
Johannes Berg <johannes@...solutions.net>,
John Keeping <john@...anate.com>,
Juergen Gross <jgross@...e.com>, Kalle Valo <kvalo@...nel.org>,
Keith Packard <keithp@...thp.com>, keyrings@...r.kernel.org,
kunit-dev@...glegroups.com,
Kuniyuki Iwashima <kuniyu@...zon.co.jp>,
"K. Y. Srinivasan" <kys@...rosoft.com>,
Lars-Peter Clausen <lars@...afoo.de>,
Lee Jones <lee.jones@...aro.org>,
Leon Romanovsky <leon@...nel.org>,
Liam Girdwood <lgirdwood@...il.com>,
linux1394-devel@...ts.sourceforge.net,
linux-afs@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org,
linux-arm-msm@...r.kernel.org, linux-bluetooth@...r.kernel.org,
linux-hardening@...r.kernel.org, linux-hyperv@...r.kernel.org,
linux-integrity@...r.kernel.org, linux-rdma@...r.kernel.org,
linux-scsi@...r.kernel.org, linux-security-module@...r.kernel.org,
linux-usb@...r.kernel.org, linux-wireless@...r.kernel.org,
linux-xtensa@...ux-xtensa.org, llvm@...ts.linux.dev,
Loic Poulain <loic.poulain@...aro.org>,
Louis Peens <louis.peens@...igine.com>,
Luca Coelho <luciano.coelho@...el.com>,
Luiz Augusto von Dentz <luiz.dentz@...il.com>,
Marc Dionne <marc.dionne@...istor.com>,
Marcel Holtmann <marcel@...tmann.org>,
Mark Brown <broonie@...nel.org>,
"Martin K. Petersen" <martin.petersen@...cle.com>,
Max Filippov <jcmvbkbc@...il.com>,
Mimi Zohar <zohar@...ux.ibm.com>,
Muchun Song <songmuchun@...edance.com>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Nuno Sá <nuno.sa@...log.com>,
Paolo Abeni <pabeni@...hat.com>,
Paul Moore <paul@...l-moore.com>,
Rob Herring <robh+dt@...nel.org>,
Russell King <linux@...linux.org.uk>, selinux@...r.kernel.org,
"Serge E. Hallyn" <serge@...lyn.com>,
SHA-cyfmac-dev-list@...ineon.com,
Simon Horman <simon.horman@...igine.com>,
Stefano Stabellini <sstabellini@...nel.org>,
Stefan Richter <stefanr@...6.in-berlin.de>,
Steffen Klassert <steffen.klassert@...unet.com>,
Stephen Hemminger <sthemmin@...rosoft.com>,
Stephen Smalley <stephen.smalley.work@...il.com>,
Tadeusz Struk <tadeusz.struk@...aro.org>,
Takashi Iwai <tiwai@...e.com>, Tom Rix <trix@...hat.com>,
Udipto Goswami <quic_ugoswami@...cinc.com>,
Vincenzo Frascino <vincenzo.frascino@....com>,
wcn36xx@...ts.infradead.org, Wei Liu <wei.liu@...nel.org>,
xen-devel@...ts.xenproject.org,
Xiu Jianfeng <xiujianfeng@...wei.com>,
Yang Yingliang <yangyingliang@...wei.com>
Subject: [PATCH 01/32] netlink: Avoid memcpy() across flexible array boundary
In preparation for run-time memcpy() bounds checking, split the nlmsg
copying for error messages (which crosses a previous unspecified flexible
array boundary) in half. Avoids the future run-time warning:
memcpy: detected field-spanning write (size 32) of single field "&errmsg->msg" (size 16)
Creates an explicit flexible array at the end of nlmsghdr for the payload,
named "nlmsg_payload". There is no impact on UAPI; the sizeof(struct
nlmsghdr) does not change, but now the compiler can better reason about
where things are being copied.
Fixed-by: Rasmus Villemoes <linux@...musvillemoes.dk>
Link: https://lore.kernel.org/lkml/d7251d92-150b-5346-6237-52afc154bb00@rasmusvillemoes.dk
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Jakub Kicinski <kuba@...nel.org>
Cc: Rich Felker <dalias@...ifal.cx>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: netdev@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
include/uapi/linux/netlink.h | 1 +
net/netlink/af_netlink.c | 5 ++++-
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h
index 855dffb4c1c3..47f9342d51bc 100644
--- a/include/uapi/linux/netlink.h
+++ b/include/uapi/linux/netlink.h
@@ -47,6 +47,7 @@ struct nlmsghdr {
__u16 nlmsg_flags; /* Additional flags */
__u32 nlmsg_seq; /* Sequence number */
__u32 nlmsg_pid; /* Sending process port ID */
+ __u8 nlmsg_payload[];/* Contents of message */
};
/* Flags values */
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 1b5a9c2e1c29..09346aee1022 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2445,7 +2445,10 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
NLMSG_ERROR, payload, flags);
errmsg = nlmsg_data(rep);
errmsg->error = err;
- memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
+ errmsg->msg = *nlh;
+ if (payload > sizeof(*errmsg))
+ memcpy(errmsg->msg.nlmsg_payload, nlh->nlmsg_payload,
+ nlh->nlmsg_len - sizeof(*nlh));
if (nlk_has_extack && extack) {
if (extack->_msg) {
--
2.32.0
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