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+9cd5837a045bbee5b810@syzkaller.appspotmail.com
Subject: [PATCH next] net: xfrm: fix shift-out-of-bounce
Date: Wed, 28 Jul 2021 19:38:18 +0300 [thread overview]
Message-ID: <20210728163818.10744-1-paskripkin@gmail.com> (raw)
We need to check up->dirmask to avoid shift-out-of-bounce bug,
since up->dirmask comes from userspace.
Also, added XFRM_USERPOLICY_DIRMASK_MAX constant to uapi to inform
user-space that up->dirmask has maximum possible value
Fixes: 2d151d39073a ("xfrm: Add possibility to set the default to block if we have no policy")
Reported-and-tested-by: syzbot+9cd5837a045bbee5b810@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
include/uapi/linux/xfrm.h | 1 +
net/xfrm/xfrm_user.c | 7 ++++++-
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/xfrm.h b/include/uapi/linux/xfrm.h
index 6e8095106192..b96c1ea7166d 100644
--- a/include/uapi/linux/xfrm.h
+++ b/include/uapi/linux/xfrm.h
@@ -514,6 +514,7 @@ struct xfrm_user_offload {
#define XFRM_OFFLOAD_INBOUND 2
struct xfrm_userpolicy_default {
+#define XFRM_USERPOLICY_DIRMASK_MAX (sizeof(__u8) * 8)
__u8 dirmask;
__u8 action;
};
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index acc3a0dab331..03b66d154b2b 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 >= XFRM_USERPOLICY_DIRMASK_MAX)
+ 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
next reply other threads:[~2021-07-28 16:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-28 16:38 Pavel Skripkin [this message]
2021-08-02 5:51 ` [PATCH next] net: xfrm: fix shift-out-of-bounce Steffen Klassert
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