Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934230AbbLRHoP (ORCPT ); Fri, 18 Dec 2015 02:44:15 -0500 Received: from mx2.suse.de ([195.135.220.15]:34819 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933567AbbLRHoN (ORCPT ); Fri, 18 Dec 2015 02:44:13 -0500 Subject: Re: [PATCH 2/2] pci: Update VPD size with correct length To: Alexander Duyck References: <1450339169-52542-1-git-send-email-hare@suse.de> <1450339169-52542-3-git-send-email-hare@suse.de> Cc: Bjorn Helgaas , Michal Kubecek , "Shane M. Seymour" , "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Bjorn Helgaas From: Hannes Reinecke Message-ID: <5673B948.9020606@suse.de> Date: Fri, 18 Dec 2015 08:44:08 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6149 Lines: 145 On 12/17/2015 06:13 PM, Alexander Duyck wrote: > On Wed, Dec 16, 2015 at 11:59 PM, Hannes Reinecke wrote: >> PCI-2.2 VPD entries have a maximum size of 32k, but might actually >> be smaller than that. To figure out the actual size one has to read >> the VPD area until the 'end marker' is reached. >> Trying to read VPD data beyond that marker results in 'interesting' >> effects, from simple read errors to crashing the card. And to make >> matters worse not every PCI card implements this properly, leaving >> us with no 'end' marker or even completely invalid data. >> This path modifies the size of the VPD attribute to the available >> size, and disables the VPD attribute altogether if no valid data >> could be read. >> >> Cc: Alexander Duyck >> Cc: Bjorn Helgaas >> Signed-off-by: Hannes Reinecke >> --- >> drivers/pci/access.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 57 insertions(+) >> >> diff --git a/drivers/pci/access.c b/drivers/pci/access.c >> index 59ac36f..0a647b1 100644 >> --- a/drivers/pci/access.c >> +++ b/drivers/pci/access.c >> @@ -475,6 +475,56 @@ static const struct pci_vpd_ops pci_vpd_f0_ops = { >> .release = pci_vpd_pci22_release, >> }; >> >> +/** >> + * pci_vpd_size - determine actual size of Vital Product Data >> + * @dev: pci device struct >> + * @old_size: current assumed size, also maximum allowed size >> + * > > "old_siz"e was dropped so you can remove this line. > >> + */ >> +static size_t >> +pci_vpd_pci22_size(struct pci_dev *dev) >> +{ >> + size_t off = 0; >> + unsigned char header[1+2]; /* 1 byte tag, 2 bytes length */ >> + >> + while (off < PCI_VPD_PCI22_SIZE && >> + pci_read_vpd(dev, off, 1, header) == 1) { >> + unsigned char tag; >> + > > The offset comparison is probably redundant. There is already a check > in pci_vpd_pci22_read that will check the offset and return -EINVAL if > we have exceeded vpd->base.len. As such you can probably just do the > pci_read_vpd comparison and drop the offset length entirely. > Indeed it does. Will be doing so. >> + if (header[0] & PCI_VPD_LRDT) { >> + /* Large Resource Data Type Tag */ >> + tag = pci_vpd_lrdt_tag(header); >> + /* Only read length from known tag items */ >> + if ((tag == PCI_VPD_LTIN_ID_STRING) || >> + (tag == PCI_VPD_LTIN_RO_DATA) || >> + (tag == PCI_VPD_LTIN_RW_DATA)) { >> + if (pci_read_vpd(dev, off+1, 2, >> + &header[1]) != 2) >> + return off + 1; >> + off += PCI_VPD_LRDT_TAG_SIZE + >> + pci_vpd_lrdt_size(header); >> + } >> + } else { >> + /* Short Resource Data Type Tag */ >> + off += PCI_VPD_SRDT_TAG_SIZE + >> + pci_vpd_srdt_size(header); >> + tag = pci_vpd_srdt_tag(header); >> + } >> + if (tag == PCI_VPD_STIN_END) /* End tag descriptor */ >> + return off; >> + if ((tag != PCI_VPD_LTIN_ID_STRING) && >> + (tag != PCI_VPD_LTIN_RO_DATA) && >> + (tag != PCI_VPD_LTIN_RW_DATA)) { >> + dev_dbg(&dev->dev, >> + "invalid %s vpd tag %02x at offset %zu.", >> + (header[0] & PCI_VPD_LRDT) ? "large" : "short", >> + tag, off); >> + break; >> + } >> + } >> + return 0; >> +} >> + >> int pci_vpd_pci22_init(struct pci_dev *dev) >> { >> struct pci_vpd_pci22 *vpd; >> @@ -497,6 +547,13 @@ int pci_vpd_pci22_init(struct pci_dev *dev) >> vpd->cap = cap; >> vpd->busy = false; >> dev->vpd = &vpd->base; >> + vpd->base.len = pci_vpd_pci22_size(dev); >> + if (vpd->base.len == 0) { >> + dev_dbg(&dev->dev, "Disabling VPD access."); >> + dev->vpd = NULL; >> + kfree(vpd); >> + return -ENXIO; >> + } >> return 0; >> } > > It looks like this still doesn't address the VPD_REF_F0 issue I > mentioned earlier. We don't need to compute the length for each > function we only need to do it once. I would recommend modifying > things so that you set vpd->base.len to 0 if the VPD_REF_F0 flag is > set. > But that would effectively inhibit access to the VPD on those devices, rendering the entire 'f0_ops' thingie quite pointless, right? I think it's better to directly retrieve the VPD length from the base pci device, that would give us the correct length _and_ save duplicate calculations. > Also I wouldn't delete the vpd configuration if the length is not > correct as that will likely break several quirks that already exist > that are setting the length. Also there is no need to return an > error, the fact is the part has VPD but we cannot determine the length > as such the correct solution is to leave it at 0. We can leave that > for a quirk to sort out later if needed. You could probably move the > dev_dbg message to just before the return 0 in the pci_vpd_pci22_size > call and drop the entire if statement in the init function. > Okay. Will be sending a new patch. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/