From 7dee5d7747a69aa2be41f04c6a7ecfe3ac8cdf18 Mon Sep 17 00:00:00 2001
From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Mon, 11 Jul 2022 17:15:19 -0700
Subject: [PATCH] sysctl: Fix data-races in proc_dou8vec_minmax().
Git-commit: 7dee5d7747a69aa2be41f04c6a7ecfe3ac8cdf18
Patch-mainline: v5.19-rc7
References: git-fixes
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_dou8vec_minmax() to use READ_ONCE() and
WRITE_ONCE() internally to fix data-races on the sysctl side. For now,
proc_dou8vec_minmax() itself is tolerant to a data-race, but we still
need to add annotations on the other subsystem's side.
Fixes: cb9444130662 ("sysctl: add proc_dou8vec_minmax()")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
kernel/sysctl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index bf9383d17e1b..b016d68da08a 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1007,13 +1007,13 @@ int proc_dou8vec_minmax(struct ctl_table *table, int write,
tmp.maxlen = sizeof(val);
tmp.data = &val;
- val = *data;
+ val = READ_ONCE(*data);
res = do_proc_douintvec(&tmp, write, buffer, lenp, ppos,
do_proc_douintvec_minmax_conv, ¶m);
if (res)
return res;
if (write)
- *data = val;
+ WRITE_ONCE(*data, val);
return 0;
}
EXPORT_SYMBOL_GPL(proc_dou8vec_minmax);
--
2.35.3