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From: Colin King <colin.king@canonical.com>
To: Johannes Berg <johannes@sipsolutions.net>,
	"David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	"John W . Linville" <linville@tuxdriver.com>,
	Luis Carlos Cobo <luisca@cozybit.com>,
	linux-wireless@vger.kernel.org, netdev@vger.kernel.org
Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] mac80211: fix potential overflow when multiplying to u32 integers
Date: Fri,  5 Feb 2021 17:53:52 +0000	[thread overview]
Message-ID: <20210205175352.208841-1-colin.king@canonical.com> (raw)

From: Colin Ian King <colin.king@canonical.com>

The multiplication of the u32 variables tx_time and estimated_retx is
performed using a 32 bit multiplication and the result is stored in
a u64 result. This has a potential u32 overflow issue, so avoid this
by casting tx_time to a u64 to force a 64 bit multiply.

Addresses-Coverity: ("Unintentional integer overflow")
Fixes: 050ac52cbe1f ("mac80211: code for on-demand Hybrid Wireless Mesh Protocol")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 net/mac80211/mesh_hwmp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c
index 313eee12410e..3db514c4c63a 100644
--- a/net/mac80211/mesh_hwmp.c
+++ b/net/mac80211/mesh_hwmp.c
@@ -356,7 +356,7 @@ u32 airtime_link_metric_get(struct ieee80211_local *local,
 	 */
 	tx_time = (device_constant + 10 * test_frame_len / rate);
 	estimated_retx = ((1 << (2 * ARITH_SHIFT)) / (s_unit - err));
-	result = (tx_time * estimated_retx) >> (2 * ARITH_SHIFT);
+	result = ((u64)tx_time * estimated_retx) >> (2 * ARITH_SHIFT);
 	return (u32)result;
 }
 
-- 
2.29.2


WARNING: multiple messages have this Message-ID (diff)
From: Colin King <colin.king@canonical.com>
To: Johannes Berg <johannes@sipsolutions.net>,
	"David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	"John W . Linville" <linville@tuxdriver.com>,
	Luis Carlos Cobo <luisca@cozybit.com>,
	linux-wireless@vger.kernel.org, netdev@vger.kernel.org
Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] mac80211: fix potential overflow when multiplying to u32 integers
Date: Fri, 05 Feb 2021 17:53:52 +0000	[thread overview]
Message-ID: <20210205175352.208841-1-colin.king@canonical.com> (raw)

From: Colin Ian King <colin.king@canonical.com>

The multiplication of the u32 variables tx_time and estimated_retx is
performed using a 32 bit multiplication and the result is stored in
a u64 result. This has a potential u32 overflow issue, so avoid this
by casting tx_time to a u64 to force a 64 bit multiply.

Addresses-Coverity: ("Unintentional integer overflow")
Fixes: 050ac52cbe1f ("mac80211: code for on-demand Hybrid Wireless Mesh Protocol")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 net/mac80211/mesh_hwmp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c
index 313eee12410e..3db514c4c63a 100644
--- a/net/mac80211/mesh_hwmp.c
+++ b/net/mac80211/mesh_hwmp.c
@@ -356,7 +356,7 @@ u32 airtime_link_metric_get(struct ieee80211_local *local,
 	 */
 	tx_time = (device_constant + 10 * test_frame_len / rate);
 	estimated_retx = ((1 << (2 * ARITH_SHIFT)) / (s_unit - err));
-	result = (tx_time * estimated_retx) >> (2 * ARITH_SHIFT);
+	result = ((u64)tx_time * estimated_retx) >> (2 * ARITH_SHIFT);
 	return (u32)result;
 }
 
-- 
2.29.2

             reply	other threads:[~2021-02-05 17:57 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-05 17:53 Colin King [this message]
2021-02-05 17:53 ` [PATCH] mac80211: fix potential overflow when multiplying to u32 integers Colin King

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