[PATCH v2 42/63] net: dccp: Use memset_startat() for TP zeroing

Kees Cook
2021-08-18T06:12:42Z

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: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: dccp@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
net/dccp/trace.h | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/dccp/trace.h b/net/dccp/trace.h
index 5062421beee9..5a43b3508c7f 100644
--- a/net/dccp/trace.h
+++ b/net/dccp/trace.h
@@ -60,9 +60,7 @@ TRACE_EVENT(dccp_probe,
__entry->tx_t_ipi = hc->tx_t_ipi;
} else {
__entry->tx_s = 0;
- memset(&__entry->tx_rtt, 0, (void *)&__entry->tx_t_ipi -
- (void *)&__entry->tx_rtt +
- sizeof(__entry->tx_t_ipi));
+ memset_startat(__entry, 0, tx_rtt);
}
),

--
2.30.2