linux-hardening - [PATCH] ath11k: Avoid memcpy() over-reading of he

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Message-Id: <20210616195410.1232119-1-keescook@chromium.org>
Date:   Wed, 16 Jun 2021 12:54:10 -0700
From:   Kees Cook <keescook@...omium.org>
To:     netdev@...r.kernel.org
Cc:     Kees Cook <keescook@...omium.org>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, linux-kernel@...r.kernel.org,
        ath11k@...ts.infradead.org, linux-wireless@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: [PATCH] ath11k: Avoid memcpy() over-reading of he_cap

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

Since peer_he_cap_{mac,phy}info and he_cap_elem.{mac,phy}_cap_info are not
the same sizes, memcpy() was reading beyond field boundaries. Instead,
correctly cap the copy length and pad out any difference in size
(peer_he_cap_macinfo is 8 bytes whereas mac_cap_info is 6, and
peer_he_cap_phyinfo is 12 bytes whereas phy_cap_info is 11).

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/net/wireless/ath/ath11k/mac.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
index 9d0ff150ec30..b1178a0b7fc3 100644
--- a/drivers/net/wireless/ath/ath11k/mac.c
+++ b/drivers/net/wireless/ath/ath11k/mac.c
@@ -1314,10 +1314,16 @@ static void ath11k_peer_assoc_h_he(struct ath11k *ar,
 
 	arg->he_flag = true;
 
-	memcpy(&arg->peer_he_cap_macinfo, he_cap->he_cap_elem.mac_cap_info,
-	       sizeof(arg->peer_he_cap_macinfo));
-	memcpy(&arg->peer_he_cap_phyinfo, he_cap->he_cap_elem.phy_cap_info,
-	       sizeof(arg->peer_he_cap_phyinfo));
+	memcpy_and_pad(&arg->peer_he_cap_macinfo,
+		       sizeof(arg->peer_he_cap_macinfo),
+		       he_cap->he_cap_elem.mac_cap_info,
+		       sizeof(he_cap->he_cap_elem.mac_cap_info),
+		       0);
+	memcpy_and_pad(&arg->peer_he_cap_phyinfo,
+		       sizeof(arg->peer_he_cap_phyinfo),
+		       he_cap->he_cap_elem.phy_cap_info,
+		       sizeof(he_cap->he_cap_elem.phy_cap_info),
+		       0);
 	arg->peer_he_ops = vif->bss_conf.he_oper.params;
 
 	/* the top most byte is used to indicate BSS color info */
-- 
2.25.1