[PATCH 40/64] net: 802: Use memset_after() to clear struct fields

Kees Cook
2021-07-27T21:06:59Z

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memset(), avoid intentionally writing across
neighboring fields.

Use memset_after() so memset() doesn't get confused about writing
beyond the destination member that is intended to be the starting point
of zeroing through the end of the struct.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
net/802/hippi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/802/hippi.c b/net/802/hippi.c
index f80b33a8f7e0..00f6666b4b16 100644
--- a/net/802/hippi.c
+++ b/net/802/hippi.c
@@ -65,7 +65,7 @@ static int hippi_header(struct sk_buff *skb, struct net_device *dev,
hip->le.src_addr_type = 2; /* 12 bit SC address */

memcpy(hip->le.src_switch_addr, dev->dev_addr + 3, 3);
- memset(&hip->le.reserved, 0, 16);
+ memset_after(&hip->le, 0, src_switch_addr);

hip->snap.dsap = HIPPI_EXTENDED_SAP;
hip->snap.ssap = HIPPI_EXTENDED_SAP;
--
2.30.2