From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 585C1C433EF for ; Tue, 10 May 2022 16:43:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347612AbiEJQrU (ORCPT ); Tue, 10 May 2022 12:47:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347610AbiEJQrO (ORCPT ); Tue, 10 May 2022 12:47:14 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E45B62CC8; Tue, 10 May 2022 09:43:12 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8FDD26183D; Tue, 10 May 2022 16:43:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3C14C385A6; Tue, 10 May 2022 16:43:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1652200991; bh=Osg1O0gfa6ZkJPjBpOrkM1rXaweWgHooysorOXbKftU=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=SG253suakgSw/EN+cXtrkyjj6aWCkxwrbCbP7C0HSUz/KfL9A6Vx4aeAY6gHLL/zK Ig/jhuTc7srNJMuXg8I3xGqrmiHxoSwZQiu5XNG+vcxoeaNuD8SwYUmAwdpg2PvtsX MpPy2zHkZCbErrHZecpOuX2nCTX41ds2hoJA0idx7X7ROHLRuS93+5p7XfBG9vBJBD +vkSNa3ypaT5L6QmF6BfBVCSIK9q3bhncdsZ5Yu4H/cJ+Yulisq7PiKnwg/z/cBrCR mVqqxmHRCgXEPo2OqbB+8jN15fPu9j2moaT3HEQDubZBxY0v4EEMpEQZCjIxPT4y4b YYOf7ALzDkFLw== Date: Tue, 10 May 2022 11:43:05 -0500 From: Bjorn Helgaas To: Mohamed Khalfella Cc: stable@vger.kernel.org, Meeta Saggi , Eric Badger , Russell Currey , Oliver O'Halloran , Rajat Jain , Bjorn Helgaas , "open list:PCI ENHANCED ERROR HANDLING (EEH) FOR POWERPC" , "open list:PCI SUBSYSTEM" , open list Subject: Re: [PATCH] PCI/AER: Iterate over error counters instead of error strings Message-ID: <20220510164305.GA678149@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220509181441.31884-1-mkhalfella@purestorage.com> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org [+cc Rajat] On Mon, May 09, 2022 at 06:14:41PM +0000, Mohamed Khalfella wrote: > PCI AER stats counters sysfs attributes need to iterate over > stats counters instead of stats names. Thanks for catching this; it definitely looks like a real issue! I guess you're probably seeing junk in the sysfs files? It would be helpful to reviewers if this said *why* we need to iterate over the counters instead of the names. I think the problem is that the current code reads past the end of the stats counters. There are parallel arrays here: #define AER_MAX_TYPEOF_COR_ERRS 16 #define AER_MAX_TYPEOF_UNCOR_ERRS 27 aer_correctable_error_string[32] # 32 pdev->aer_stats->dev_cor_errs[AER_MAX_TYPEOF_COR_ERRS] # 16 aer_uncorrectable_error_string[32] # 32 pdev->aer_stats->dev_fatal_errs[AER_MAX_TYPEOF_UNCOR_ERRS] # 27 pdev->aer_stats->dev_nonfatal_errs[AER_MAX_TYPEOF_UNCOR_ERRS] # 27 And here's the current use of them: #define aer_stats_dev_attr(..., stats_array, strings_array, ...) for (i = 0; i < ARRAY_SIZE(strings_array); i++) { if (strings_array[i]) sysfs_emit_at(..., strings_array[i], stats[i]); (1) else if (stats[i]) sysfs_emit_at(..., stats[i]); (2) aer_stats_dev_attr(..., dev_cor_errs, aer_correctable_error_string, aer_stats_dev_attr(..., dev_fatal_errs, aer_uncorrectable_error_string, aer_stats_dev_attr(..., dev_nonfatal_errs, aer_uncorrectable_error_string, The current loop iterates over 0..31, which is safe at (1) because the non-NULL strings are at aer_correctable_error_string[0..15] and aer_uncorrectable_error_string[0..26]. But it is unsafe at (2) because it references dev_cor_errs[16..31], dev_fatal_errs[27..31], and dev_nonfatal_errs[27..31], which are past the end of the arrays. > Also, added a build time check to make sure all counters have > entries in strings array. > > Fixes: 0678e3109a3c ("PCI/AER: Simplify __aer_print_error()") Yep, I blew it there. Rajat did it correctly when he added this with 81aa5206f9a7 ("PCI/AER: Add sysfs attributes to provide AER stats and breakdown"), and I broke it by extending the string arrays to 32 entries. > Cc: stable@vger.kernel.org > Reported-by: Meeta Saggi > Signed-off-by: Mohamed Khalfella > Reviewed-by: Meeta Saggi > Reviewed-by: Eric Badger > --- > drivers/pci/pcie/aer.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c > index 9fa1f97e5b27..ce99a6d44786 100644 > --- a/drivers/pci/pcie/aer.c > +++ b/drivers/pci/pcie/aer.c > @@ -533,7 +533,7 @@ static const char *aer_agent_string[] = { > u64 *stats = pdev->aer_stats->stats_array; \ > size_t len = 0; \ > \ > - for (i = 0; i < ARRAY_SIZE(strings_array); i++) { \ > + for (i = 0; i < ARRAY_SIZE(pdev->aer_stats->stats_array); i++) {\ > if (strings_array[i]) \ > len += sysfs_emit_at(buf, len, "%s %llu\n", \ > strings_array[i], \ I think maybe we should populate the currently NULL entries in the string[] arrays and simplify the code here, e.g., static const char *aer_correctable_error_string[] = { "RxErr", /* Bit Position 0 */ "dev_cor_errs_bit[1]", ... if (stats[i]) len += sysfs_emit_at(buf, len, "%s %llu\n", strings_array[i], stats[i]); It's a little more data space, but easier to verify. > @@ -1342,6 +1342,11 @@ static int aer_probe(struct pcie_device *dev) > struct device *device = &dev->device; > struct pci_dev *port = dev->port; > > + BUILD_BUG_ON(ARRAY_SIZE(aer_correctable_error_string) < > + AER_MAX_TYPEOF_COR_ERRS); > + BUILD_BUG_ON(ARRAY_SIZE(aer_uncorrectable_error_string) < > + AER_MAX_TYPEOF_UNCOR_ERRS); And make these check for "!=" instead of "<".