Commit 3c10ffdd authored by Pavel Skripkin's avatar Pavel Skripkin Committed by Steffen Klassert
Browse files

net: xfrm: fix shift-out-of-bounds in xfrm_get_default 



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: 2d151d39 ("xfrm: Add possibility to set the default to block if we have no policy")
Reported-and-tested-by: default avatar <syzbot+b2be9dd8ca6f6c73ee2d@syzkaller.appspotmail.com>
Signed-off-by: default avatarPavel Skripkin <paskripkin@gmail.com>
Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
parent 626bf91a

net/xfrm/xfrm_user.c

+5 −0
Original line number Diff line number Diff line
@@ -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);