linux-kernel - [PATCH] igb: Avoid memcpy() over-reading of ETH_SS

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Message-Id: <20210616195319.1231564-1-keescook@chromium.org>
Date:   Wed, 16 Jun 2021 12:53:19 -0700
From:   Kees Cook <keescook@...omium.org>
To:     netdev@...r.kernel.org
Cc:     Kees Cook <keescook@...omium.org>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, linux-kernel@...r.kernel.org,
        intel-wired-lan@...ts.osuosl.org, linux-hardening@...r.kernel.org
Subject: [PATCH] igb: Avoid memcpy() over-reading of ETH_SS_STATS

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

The memcpy() is copying the entire structure, not just the first array.
Adjust the source argument so the compiler can do appropriate bounds
checking.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/net/ethernet/intel/igb/igb_ethtool.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb_ethtool.c b/drivers/net/ethernet/intel/igb/igb_ethtool.c
index 636a1b1fb7e1..17f5c003c3df 100644
--- a/drivers/net/ethernet/intel/igb/igb_ethtool.c
+++ b/drivers/net/ethernet/intel/igb/igb_ethtool.c
@@ -2343,8 +2343,7 @@ static void igb_get_strings(struct net_device *netdev, u32 stringset, u8 *data)
 
 	switch (stringset) {
 	case ETH_SS_TEST:
-		memcpy(data, *igb_gstrings_test,
-			IGB_TEST_LEN*ETH_GSTRING_LEN);
+		memcpy(data, igb_gstrings_test, sizeof(igb_gstrings_test));
 		break;
 	case ETH_SS_STATS:
 		for (i = 0; i < IGB_GLOBAL_STATS_LEN; i++)
-- 
2.25.1