From d335db59f7fb3353f56e52371f1ee796ae9c8f09 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Wed, 6 Jul 2022 16:39:53 -0700 Subject: [PATCH] sysctl: Fix data races in proc_douintvec(). [ Upstream commit 4762b532ec9539755aab61445d5da6e1926ccb99 ] 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_douintvec() to use READ_ONCE() and WRITE_ONCE() internally to fix data-races on the sysctl side. For now, proc_douintvec() itself is tolerant to a data-race, but we still need to add annotations on the other subsystem's side. Fixes: e7d316a02f68 ("sysctl: handle error writing UINT_MAX to u32 fields") Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- kernel/sysctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 11f0714..b152e0a 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -592,9 +592,9 @@ static int do_proc_douintvec_conv(unsigned long *lvalp, if (write) { if (*lvalp > UINT_MAX) return -EINVAL; - *valp = *lvalp; + WRITE_ONCE(*valp, *lvalp); } else { - unsigned int val = *valp; + unsigned int val = READ_ONCE(*valp); *lvalp = (unsigned long)val; } return 0; -- 2.7.4