From: Pavel Skripkin <paskripkin@gmail.com>
To: steffen.klassert@secunet.com, herbert@gondor.apana.org.au,
davem@davemloft.net, kuba@kernel.org
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Pavel Skripkin <paskripkin@gmail.com>,
syzbot+b2be9dd8ca6f6c73ee2d@syzkaller.appspotmail.com
Subject: [PATCH] net: xfrm: fix shift-out-of-bounds in xfrm_get_default
Date: Thu, 2 Sep 2021 22:04:00 +0300 [thread overview]
Message-ID: <20210902190400.5257-1-paskripkin@gmail.com> (raw)
Syzbot hit shift-out-of-bounds in xfrm_get_default. The problem was in
missing validation check for user data.
up->dirmask comes from user-space, so we need to check if this value
is less than XFRM_USERPOLICY_DIRMASK_MAX to avoid shift-out-of-bounds bugs.
Fixes: 2d151d39073a ("xfrm: Add possibility to set the default to block if we have no policy")
Reported-and-tested-by: syzbot+b2be9dd8ca6f6c73ee2d@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
net/xfrm/xfrm_user.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index b7b986520dc7..e4cf48c71315 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -2005,6 +2005,11 @@ static int xfrm_get_default(struct sk_buff *skb, struct nlmsghdr *nlh,
return -EMSGSIZE;
}
+ if (up->dirmask >= XFRM_USERPOLICY_DIRMASK_MAX) {
+ kfree_skb(r_skb);
+ return -EINVAL;
+ }
+
r_up = nlmsg_data(r_nlh);
r_up->action = ((net->xfrm.policy_default & (1 << up->dirmask)) >> up->dirmask);
--
2.33.0
next reply other threads:[~2021-09-02 19:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-02 19:04 Pavel Skripkin [this message]
2021-09-10 9:50 ` [PATCH] net: xfrm: fix shift-out-of-bounds in xfrm_get_default Steffen Klassert
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