This is a note to let you know that I've just added the patch titled
sysctl: Fix data races in proc_doulongvec_minmax().
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sysctl-fix-data-races-in-proc_doulongvec_minmax.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 38f488e5935fb476f1bc42f0e379a2ff33cbfab6
Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Date: Wed Jul 6 16:39:56 2022 -0700
sysctl: Fix data races in proc_doulongvec_minmax().
[ Upstream commit c31bcc8fb89fc2812663900589c6325ba35d9a65 ]
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: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index a769f64a78ed..7a8899f237a2 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1162,9 +1162,9 @@ 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);
