From f177b382c33900d0e5a9766493c11a1074076f78 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Mon, 11 Jul 2022 17:15:19 -0700 Subject: [PATCH] sysctl: Fix data-races in proc_dou8vec_minmax(). commit 7dee5d7747a69aa2be41f04c6a7ecfe3ac8cdf18 upstream. 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 Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- kernel/sysctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 43e907f4cac7..d981abea0358 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1109,13 +1109,13 @@ 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);