linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Pavel Skripkin <paskripkin@gmail.com>
To: syzbot <syzbot+9cd5837a045bbee5b810@syzkaller.appspotmail.com>
Cc: davem@davemloft.net, herbert@gondor.apana.org.au,
	kuba@kernel.org, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org, steffen.klassert@secunet.com,
	syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] UBSAN: shift-out-of-bounds in xfrm_set_default
Date: Tue, 27 Jul 2021 17:43:18 +0300	[thread overview]
Message-ID: <20210727174318.53806d27@gmail.com> (raw)
In-Reply-To: <0000000000004f5de905c81a45e7@google.com>

[-- Attachment #1: Type: text/plain, Size: 1256 bytes --]

On Tue, 27 Jul 2021 05:47:21 -0700
syzbot <syzbot+9cd5837a045bbee5b810@syzkaller.appspotmail.com> wrote:

> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    90d856e71443 Add linux-next specific files for
> 20210723 git tree:       linux-next
> console output:
> https://syzkaller.appspot.com/x/log.txt?x=133fd00a300000 kernel
> config:  https://syzkaller.appspot.com/x/.config?x=298516715f6ad5cd
> dashboard link:
> https://syzkaller.appspot.com/bug?extid=9cd5837a045bbee5b810
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU
> Binutils for Debian) 2.35.1 syz repro:
> https://syzkaller.appspot.com/x/repro.syz?x=1263bba6300000 C
> reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1066b4d4300000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the
> commit: Reported-by:
> syzbot+9cd5837a045bbee5b810@syzkaller.appspotmail.com
> 
> netlink: 228 bytes leftover after parsing attributes in process
> `syz-executor669'.
> ================================================================================


The first thing that comes in mind is to check up->dirmask value


#syz test
git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master 


With regards,
Pavel Skripkin



[-- Attachment #2: 0001-net-xfrm-fix-shift-out-of-bounce.patch --]
[-- Type: text/x-patch, Size: 1152 bytes --]

From 30db223b1f724ca241c7fa15769d0c65eada3b66 Mon Sep 17 00:00:00 2001
From: Pavel Skripkin <paskripkin@gmail.com>
Date: Tue, 27 Jul 2021 17:38:24 +0300
Subject: [PATCH] net: xfrm: fix shift-out-of-bounce

We need to check up->dirmask to avoid shift-out-of-bounce bug,
since up->dirmask comes from userspace.

Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
 net/xfrm/xfrm_user.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index acc3a0dab331..5f3fe2295519 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1966,9 +1966,14 @@ static int xfrm_set_default(struct sk_buff *skb, struct nlmsghdr *nlh,
 {
 	struct net *net = sock_net(skb->sk);
 	struct xfrm_userpolicy_default *up = nlmsg_data(nlh);
-	u8 dirmask = (1 << up->dirmask) & XFRM_POL_DEFAULT_MASK;
+	u8 dirmask;
 	u8 old_default = net->xfrm.policy_default;
 
+	if (up->dirmask >= sizeof(up->action) * 8)
+		return -EINVAL;
+
+	dirmask = (1 << up->dirmask) & XFRM_POL_DEFAULT_MASK
+
 	net->xfrm.policy_default = (old_default & (0xff ^ dirmask))
 				    | (up->action << up->dirmask);
 
-- 
2.32.0


  reply	other threads:[~2021-07-27 14:43 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-27 12:47 syzbot
2021-07-27 14:43 ` Pavel Skripkin [this message]
2021-07-27 17:25   ` [PATCH] net: xfrm: fix shift-out-of-bounce kernel test robot
2021-07-27 17:30     ` Pavel Skripkin
2021-07-28  0:13       ` [syzbot] UBSAN: shift-out-of-bounds in xfrm_set_default syzbot
2021-07-27 17:46   ` [PATCH] net: xfrm: fix shift-out-of-bounce kernel test robot
2021-07-27 23:28   ` [syzbot] UBSAN: shift-out-of-bounds in xfrm_set_default syzbot

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=20210727174318.53806d27@gmail.com \
    --to=paskripkin@gmail.com \
    --cc=davem@davemloft.net \
    --cc=herbert@gondor.apana.org.au \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=steffen.klassert@secunet.com \
    --cc=syzbot+9cd5837a045bbee5b810@syzkaller.appspotmail.com \
    --cc=syzkaller-bugs@googlegroups.com \
    --subject='Re: [syzbot] UBSAN: shift-out-of-bounds in xfrm_set_default' \
    /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

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).