From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: [PATCH 1/5] netfilter: nfnetlink: Improve input length sanitization in nfnetlink_rcv
Date: Tue, 18 Jul 2017 12:13:55 +0200 [thread overview]
Message-ID: <1500372839-6735-2-git-send-email-pablo@netfilter.org> (raw)
In-Reply-To: <1500372839-6735-1-git-send-email-pablo@netfilter.org>
From: Mateusz Jurczyk <mjurczyk@google.com>
Verify that the length of the socket buffer is sufficient to cover the
nlmsghdr structure before accessing the nlh->nlmsg_len field for further
input sanitization. If the client only supplies 1-3 bytes of data in
sk_buff, then nlh->nlmsg_len remains partially uninitialized and
contains leftover memory from the corresponding kernel allocation.
Operating on such data may result in indeterminate evaluation of the
nlmsg_len < NLMSG_HDRLEN expression.
The bug was discovered by a runtime instrumentation designed to detect
use of uninitialized memory in the kernel. The patch prevents this and
other similar tools (e.g. KMSAN) from flagging this behavior in the future.
Signed-off-by: Mateusz Jurczyk <mjurczyk@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/netfilter/nfnetlink.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 92b05e188fd1..733d3e4a30d8 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -472,8 +472,7 @@ static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
if (msglen > skb->len)
msglen = skb->len;
- if (nlh->nlmsg_len < NLMSG_HDRLEN ||
- skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
+ if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
return;
err = nla_parse(cda, NFNL_BATCH_MAX, attr, attrlen, nfnl_batch_policy,
@@ -500,7 +499,8 @@ static void nfnetlink_rcv(struct sk_buff *skb)
{
struct nlmsghdr *nlh = nlmsg_hdr(skb);
- if (nlh->nlmsg_len < NLMSG_HDRLEN ||
+ if (skb->len < NLMSG_HDRLEN ||
+ nlh->nlmsg_len < NLMSG_HDRLEN ||
skb->len < nlh->nlmsg_len)
return;
--
2.1.4
next prev parent reply other threads:[~2017-07-18 10:14 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-18 10:13 [PATCH 0/5] Netfilter fixes for net Pablo Neira Ayuso
2017-07-18 10:13 ` Pablo Neira Ayuso [this message]
2017-07-18 10:13 ` [PATCH 2/5] netfilter: remove old pre-netns era hook api Pablo Neira Ayuso
2017-07-18 10:13 ` [PATCH 3/5] netfilter: nat: fix src map lookup Pablo Neira Ayuso
2017-07-18 10:13 ` [PATCH 4/5] netfilter: nf_tables: only allow in/output for arp packets Pablo Neira Ayuso
2017-07-18 10:13 ` [PATCH 5/5] netfilter: expect: fix crash when putting uninited expectation Pablo Neira Ayuso
2017-07-18 19:03 ` [PATCH 0/5] Netfilter fixes for net David Miller
2017-07-18 21:11 ` Florian Westphal
2017-07-18 21:54 ` David Miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1500372839-6735-2-git-send-email-pablo@netfilter.org \
--to=pablo@netfilter.org \
--cc=davem@davemloft.net \
--cc=netdev@vger.kernel.org \
--cc=netfilter-devel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).