[Linux-kernel-mentees] [PATCH v2] net: ipv6: fix use-after-free Read in __xfrm6_tunnel_spi_lookup

[David Miller]

From: B K Karthik <bkkarthik at pesu.pes.edu>
Date: Sun, 26 Jul 2020 08:38:55 +0530

> @@ -103,10 +103,10 @@ static int __xfrm6_tunnel_spi_check(struct net *net, u32 spi)
>  {
>  	struct xfrm6_tunnel_net *xfrm6_tn = xfrm6_tunnel_pernet(net);
>  	struct xfrm6_tunnel_spi *x6spi;
> -	int index = xfrm6_tunnel_spi_hash_byspi(spi);
> +	int index = xfrm6_tunnel_spi_hash_byaddr((const xfrm_address_t *)spi);

We can cast this a thousand times to make the compiler quiet, but the
fact is that this function does not expect an integer SPI as an
argument.

It expects a protocol address.

Please stop forcing this fix, I fear you don't understand how this code
works.  Come back to us when you do.

Thank you.