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 545B314A0BC; Tue, 25 Jun 2024 09:48:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719308886; cv=none; b=JbYvZDUBaOzPn0MTAVBA09CWdzaek9sBI1QwGE5rixOAwb09KqNOl2Ixmzr/bipPxZCZE7VmymML2xk4Qvp2fWvIo+/PW6rJPU38cWpIXfNDxhkBVShytHZyjyq2M1usdTxhhkYbI0N4FI4tp+NsVoHeArJD8bFXRtkQS+Q2D8Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719308886; c=relaxed/simple; bh=oD0UCP8zKi+s44jtUVN/hjlgnvY7qoLDgj1y6jvjdUo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VjcHiXTmQUsr64QIgzTedBcSVEWZooUV/+0e9+yfO+Sr59PJcyEwzLaXwOwGTuiuo1n2UVctnoMWK1J8CHbUKZUFqntFNpH5LfD5+PiD/lQJgvkFWxoPmCCgg42uGyOpW8M0uaLxmssLjKZMZjVRml/HQnWtLr1uX/626Hy9UPA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=hyq0pBgp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="hyq0pBgp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CDDE3C32781; Tue, 25 Jun 2024 09:48:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1719308886; bh=oD0UCP8zKi+s44jtUVN/hjlgnvY7qoLDgj1y6jvjdUo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hyq0pBgpb5vreWPFOLv+Sl4rS/28laVm4fOtuWHS99i7Uou6SYQ2FvO1dlKOaWEC7 ssiGptLTPbH3TqpNA4GTKrrDYWWOnvcERE0TtWhr4W1EM7oRuh+zqNXG/W2bptntWm ucZ9qf4Iz5NwHKxIIcLHYcPyCVDMXohbcZTSo3hc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Breno Leitao , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.6 023/192] netpoll: Fix race condition in netpoll_owner_active Date: Tue, 25 Jun 2024 11:31:35 +0200 Message-ID: <20240625085538.047748479@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240625085537.150087723@linuxfoundation.org> References: <20240625085537.150087723@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Breno Leitao [ Upstream commit c2e6a872bde9912f1a7579639c5ca3adf1003916 ] KCSAN detected a race condition in netpoll: BUG: KCSAN: data-race in net_rx_action / netpoll_send_skb write (marked) to 0xffff8881164168b0 of 4 bytes by interrupt on cpu 10: net_rx_action (./include/linux/netpoll.h:90 net/core/dev.c:6712 net/core/dev.c:6822) read to 0xffff8881164168b0 of 4 bytes by task 1 on cpu 2: netpoll_send_skb (net/core/netpoll.c:319 net/core/netpoll.c:345 net/core/netpoll.c:393) netpoll_send_udp (net/core/netpoll.c:?) value changed: 0x0000000a -> 0xffffffff This happens because netpoll_owner_active() needs to check if the current CPU is the owner of the lock, touching napi->poll_owner non atomically. The ->poll_owner field contains the current CPU holding the lock. Use an atomic read to check if the poll owner is the current CPU. Signed-off-by: Breno Leitao Link: https://lore.kernel.org/r/20240429100437.3487432-1-leitao@debian.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/core/netpoll.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/netpoll.c b/net/core/netpoll.c index 543007f159f99..55bcacf67df3b 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -316,7 +316,7 @@ static int netpoll_owner_active(struct net_device *dev) struct napi_struct *napi; list_for_each_entry_rcu(napi, &dev->napi_list, dev_list) { - if (napi->poll_owner == smp_processor_id()) + if (READ_ONCE(napi->poll_owner) == smp_processor_id()) return 1; } return 0; -- 2.43.0