This is a note to let you know that I've just added the patch titled
sysctl: Fix data-races in proc_dou8vec_minmax().
to the 5.10-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_dou8vec_minmax.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7dee5d7747a69aa2be41f04c6a7ecfe3ac8cdf18 Mon Sep 17 00:00:00 2001
From: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Date: Mon, 11 Jul 2022 17:15:19 -0700
Subject: sysctl: Fix data-races in proc_dou8vec_minmax().
From: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
commit 7dee5d7747a69aa2be41f04c6a7ecfe3ac8cdf18 upstream.
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_dou8vec_minmax() to use READ_ONCE() and
WRITE_ONCE() internally to fix data-races on the sysctl side. For now,
proc_dou8vec_minmax() itself is tolerant to a data-race, but we still
need to add annotations on the other subsystem's side.
Fixes: cb9444130662 ("sysctl: add proc_dou8vec_minmax()")
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/sysctl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1109,13 +1109,13 @@ int proc_dou8vec_minmax(struct ctl_table
tmp.maxlen = sizeof(val);
tmp.data = &val;
- val = *data;
+ val = READ_ONCE(*data);
res = do_proc_douintvec(&tmp, write, buffer, lenp, ppos,
do_proc_douintvec_minmax_conv, ¶m);
if (res)
return res;
if (write)
- *data = val;
+ WRITE_ONCE(*data, val);
return 0;
}
EXPORT_SYMBOL_GPL(proc_dou8vec_minmax);
Patches currently in stable-queue which might be from kuniyu@xxxxxxxxxx are
queue-5.10/sysctl-fix-data-races-in-proc_dou8vec_minmax.patch
queue-5.10/tcp-restrict-net.ipv4.tcp_app_win.patch
