Commit aaf271fc authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by sanglipeng
Browse files

sysctl: Fix data-races in proc_dou8vec_minmax(). 

stable inclusion
from stable-v5.10.178
commit f177b382c33900d0e5a9766493c11a1074076f78
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8ALH3

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f177b382c33900d0e5a9766493c11a1074076f78



--------------------------------

commit 7dee5d77 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: cb944413 ("sysctl: add proc_dou8vec_minmax()")
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarsanglipeng <sanglipeng1@jd.com>
parent 55793a96

kernel/sysctl.c

+2 −2
Original line number Diff line number Diff line
@@ -1114,13 +1114,13 @@ 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, &param);

	if (res)

		return res;

	if (write)

		*data = val;

		WRITE_ONCE(*data, val);

	return 0;

}

EXPORT_SYMBOL_GPL(proc_dou8vec_minmax);