Re: [PATCH][next] net/ipv6/mcast: Use struct_size() helper

Replace IP6_SFLSIZE() with struct_size() helper in order to avoid any
potential type mistakes or integer overflows that, in the worst
scenario, could lead to heap overflows.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 include/net/if_inet6.h |  3 ---
 net/ipv6/mcast.c       | 20 +++++++++++++-------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h
index 71bb4cc4d05d..42235c178b06 100644
--- a/include/net/if_inet6.h
+++ b/include/net/if_inet6.h

@@ -82,9 +82,6 @@ struct ip6_sf_socklist {
 	struct in6_addr		sl_addr[];
 };
 
-#define IP6_SFLSIZE(count)	(sizeof(struct ip6_sf_socklist) + \
-	(count) * sizeof(struct in6_addr))
-
 #define IP6_SFBLOCK	10	/* allocate this many at once */
 
 struct ipv6_mc_socklist {

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 54ec163fbafa..cd951faa2fac 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c

@@ -447,7 +447,8 @@ int ip6_mc_source(int add, int omode, struct sock *sk,
 
 		if (psl)
 			count += psl->sl_max;
-		newpsl = sock_kmalloc(sk, IP6_SFLSIZE(count), GFP_KERNEL);
+		newpsl = sock_kmalloc(sk, struct_size(newpsl, sl_addr, count),
+				      GFP_KERNEL);