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

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
......@@ -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);
......
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