Commit 4762b532 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by David S. Miller
Browse files

sysctl: Fix data races in proc_douintvec(). 



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: e7d316a0 ("sysctl: handle error writing UINT_MAX to u32 fields")
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1f1be04b

kernel/sysctl.c

+2 −2
Original line number Diff line number Diff line
@@ -472,9 +472,9 @@ 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;