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Message-ID: <20230210123644.489-1-svc.sw.rte.linux@sma.de>
Date: Fri, 10 Feb 2023 13:36:44 +0100
From: Felix Riemann <svc.sw.rte.linux@....de>
To: <netdev@...r.kernel.org>
CC: <linux-kernel@...r.kernel.org>, Eric Dumazet <edumazet@...gle.com>,
"Jakub Kicinski" <kuba@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
"Felix Riemann" <felix.riemann@....de>
Subject: [PATCH] net: Fix unwanted sign extension in netdev_stats_to_stats64()
From: Felix Riemann <felix.riemann@....de>
When converting net_device_stats to rtnl_link_stats64 sign extension
is triggered on ILP32 machines as 6c1c509778 changed the previous
"ulong -> u64" conversion to "long -> u64" by accessing the
net_device_stats fields through a (signed) atomic_long_t.
This causes for example the received bytes counter to jump to 16EiB after
having received 2^31 bytes. Casting the atomic value to "unsigned long"
beforehand converting it into u64 avoids this.
Fixes: 6c1c5097781f ("net: add atomic_long_t to net_device_stats fields")
Signed-off-by: Felix Riemann <felix.riemann@....de>
---
net/core/dev.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index b76fb37b381e..ea0a7bac1e5c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10375,7 +10375,7 @@ void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64,
BUILD_BUG_ON(n > sizeof(*stats64) / sizeof(u64));
for (i = 0; i < n; i++)
- dst[i] = atomic_long_read(&src[i]);
+ dst[i] = (unsigned long)atomic_long_read(&src[i]);
/* zero out counters that only exist in rtnl_link_stats64 */
memset((char *)stats64 + n * sizeof(u64), 0,
sizeof(*stats64) - n * sizeof(u64));
--
2.35.3
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