Re: [PATCH net] xfrm: fix integer overflow in xfrm_replay_state_esn_len()

On Wed, Jan 22, 2025 at 12:39:36PM +0000, Simon Horman wrote:

quoted

quoted

The one caller that I didn't modify was xfrm_sa_len().  That's a bit
complicated and also I'm kind of hoping that we don't handle user
controlled data in that function?  The place where we definitely are
handling user data is in xfrm_alloc_replay_state_esn() and this patch
fixes that.

Yes, that is a bit "complex".

I don't have a reason to suspect xfrm_sa_len() but if we were to write
a paranoid version of it then I've written that draft below.  I stole
Herbert's xfrm_kblen2klen() function[1].  Also the nlmsg_new() function
would need to be updated as well.

https://lore.kernel.org/all/Z2KZC71JZ0QnrhfU@gondor.apana.org.au/ (local)

regards,
dan carpenter

diff --git a/include/net/netlink.h b/include/net/netlink.h
index e015ffbed819..ca7a8152e6d4 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h

@@ -1015,6 +1015,8 @@ static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb,
  */
 static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags)
 {
+	if (payload > INT_MAX)
+		return NULL;
 	return alloc_skb(nlmsg_total_size(payload), flags);
 }