Commit c31bcc8f authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by David S. Miller
Browse files

sysctl: Fix data races in proc_doulongvec_minmax(). 



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_doulongvec_minmax() to use READ_ONCE() and
WRITE_ONCE() internally to fix data-races on the sysctl side.  For now,
proc_doulongvec_minmax() itself is tolerant to a data-race, but we still
need to add annotations on the other subsystem's side.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2d3b559d

kernel/sysctl.c

+2 −2
Original line number Diff line number Diff line
@@ -1090,9 +1090,9 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, 
				err = -EINVAL;

				break;

			}

			*i = val;

			WRITE_ONCE(*i, val);

		} else {

			val = convdiv * (*i) / convmul;

			val = convdiv * READ_ONCE(*i) / convmul;

			if (!first)

				proc_put_char(&buffer, &left, '\t');

			proc_put_long(&buffer, &left, val, false);