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Subject[PATCH v2 net 03/12] sysctl: Fix data races in proc_dointvec_minmax().
Date
A sysctl variable is accessed concurrently, and there is always a chance
of data-race. So, all readers and writers need some basic protection to
avoid load/store-tearing.

This patch changes proc_dointvec_minmax() to use READ_ONCE() and
WRITE_ONCE() internally to fix data-races on the sysctl side. For now,
proc_dointvec_minmax() itself is tolerant to a data-race, but we still
need to add annotations on the other subsystem's side.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
kernel/sysctl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 2ab8c2a37e8f..4d87832367f2 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -857,7 +857,7 @@ static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
if ((param->min && *param->min > tmp) ||
(param->max && *param->max < tmp))
return -EINVAL;
- *valp = tmp;
+ WRITE_ONCE(*valp, tmp);
}

return 0;
--
2.30.2
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