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 E407273443; Mon, 27 May 2024 14:18:39 +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=1716819520; cv=none; b=hk64UesegBMJGD4DNnDlV7c4sjRifchJVj8BEvT96FFnYSuLiTuaFo7kjVmj+dLXTzLBfY7CpGyqvpwFjE/760SAXCF8oi7/uKr5sjeemXC9/uDVwoJPgDS6SrlKc6PXf5DiF484RLewjPxcPrayTci4TwPi8K7Z3V8XRvMoyrI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716819520; c=relaxed/simple; bh=LFdVJ1u8oZJXp9vkV1GNaoYs334Var2HnGA/TUOuOGw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lNWVHxJxMnvjI7qosBRCeye/iwYCysb/apezclXujC1r7cVBOSJGjTzTwxZyNRZAryJzO6rn3dqTe+/65J7YlbbLhy8o57c7PUY40k4qHWzn2EaOAAENO5hVdP6mmE/wxIPmTSNIbq9h1TUJbsj2jPzUeU00Wt7l+77g0fVbPBM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YBl1XbtK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YBl1XbtK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7EC59C2BBFC; Mon, 27 May 2024 14:18:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1716819519; bh=LFdVJ1u8oZJXp9vkV1GNaoYs334Var2HnGA/TUOuOGw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YBl1XbtKWv6m9JS+xm62zvgqnQ0GYk3gs6ziV24obutqJItqa9FLGbeXjgAMQA9n9 Y1OXIN/UHTCHV9sWqswO+BDoy+2BFnlB0kR0pq07uDBt8HE5fZD00K0CPO2Oe+Kfa3 HAuvv/u/F2pig8RwcVJWIA4DpzhIfMHhx6+0onjZfVf4De0hCLF7kIZ4rCwV8747kq L7KPUfsSRFSkCUZvH8aTcyCZKMIKnIzLO8dbsyX5TAraZK/9xTEwyhCa/ebWXIQWGf eiOb1sJn/VObe2/1cmBP20Q4I+NMZ6Y0Lvtrci91ObwfozAUjX/Kr6RRYGvJBCwAUT 6MVc53s8+RWHg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Breno Leitao , Jakub Kicinski , Sasha Levin , davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 5.15 09/13] netpoll: Fix race condition in netpoll_owner_active Date: Mon, 27 May 2024 10:18:03 -0400 Message-ID: <20240527141819.3854376-9-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240527141819.3854376-1-sashal@kernel.org> References: <20240527141819.3854376-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.15.160 Content-Transfer-Encoding: 8bit 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 47a86da6ab980..2a9d95368d5a2 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