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[v2,41/63] net: 802: Use memset_startat() to clear struct fields

Message ID 20210818060533.3569517-42-keescook@chromium.org
State New
Headers show
Series Introduce strict memcpy() bounds checking | expand

Commit Message

Kees Cook Aug. 18, 2021, 6:05 a.m. UTC 
In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memset(), avoid intentionally writing across
neighboring fields.

Use memset_startat() 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.

Cc: Jes Sorensen <jes@trained-monkey.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: linux-hippi@sunsite.dk
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 net/802/hippi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/net/802/hippi.c b/net/802/hippi.c
index f80b33a8f7e0..6f71ffc8bdd1 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_startat(&hip->le, 0, reserved);
 
 	hip->snap.dsap		= HIPPI_EXTENDED_SAP;
 	hip->snap.ssap		= HIPPI_EXTENDED_SAP;