From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4197C2566 for ; Tue, 18 Apr 2023 12:37:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9175AC433D2; Tue, 18 Apr 2023 12:37:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1681821450; bh=1y4PA2klK5CJIppKYN0NfdsAoMVOfzFHA8PPCfP8ovY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=k36PcwAGlPyI4CMnvlEngXVJGLiOHSBer4jC1Cz61xh29MHTdcn00I9ts4Yyo2XGL RNqzKoUWaDJsI/FOtOgNbvPQDNyydWEYqrHyrVEyIULD7cXYicnNsaO2c9D4hzzLg7 sIM5nCWFxBoo9lSZiQo00Zh2KE2l8sn/JeIsTyoQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kuniyuki Iwashima , "David S. Miller" Subject: [PATCH 5.10 124/124] sysctl: Fix data-races in proc_dou8vec_minmax(). Date: Tue, 18 Apr 2023 14:22:23 +0200 Message-Id: <20230418120314.256095418@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230418120309.539243408@linuxfoundation.org> References: <20230418120309.539243408@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Kuniyuki Iwashima 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 Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- 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);