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From: "Saheed O. Bolarinwa" <refactormyself@gmail.com>
To: helgaas@kernel.org, "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Len Brown <lenb@kernel.org>
Cc: "Saheed O. Bolarinwa" <refactormyself@gmail.com>,
	bjorn@helgaas.com, skhan@linuxfoundation.org,
	linux-pci@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org,
	linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org
Subject: [PATCH v4 07/12] PCI/ACPI: Check if pcie_capability_read_*() reads ~0
Date: Fri, 31 Jul 2020 13:02:35 +0200
Message-ID: <20200731110240.98326-8-refactormyself@gmail.com> (raw)
In-Reply-To: <20200731110240.98326-1-refactormyself@gmail.com>

On failure pcie_capability_read_*() sets it's last parameter, val
to 0. However, with Patch 12/12, it is possible that val is set
to ~0 on failure. This would introduces a bug because
(x & x) == (~0 & x).

Since ~0 is an invalid value in here,

Add extra check for ~0 in the if condition to ensure success or
failure.

Suggested-by: Bjorn Helgaas <bjorn@helgaas.com>
Signed-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
---
 drivers/pci/pci-acpi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 7224b1e5f2a8..873b005947e4 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -253,7 +253,7 @@ static bool pcie_root_rcb_set(struct pci_dev *dev)
 		return false;
 
 	pcie_capability_read_word(rp, PCI_EXP_LNKCTL, &lnkctl);
-	if (lnkctl & PCI_EXP_LNKCTL_RCB)
+	if ((lnkctl != (u16)~0) && (lnkctl & PCI_EXP_LNKCTL_RCB))
 		return true;
 
 	return false;
@@ -797,7 +797,7 @@ bool pciehp_is_native(struct pci_dev *bridge)
 		return false;
 
 	pcie_capability_read_dword(bridge, PCI_EXP_SLTCAP, &slot_cap);
-	if (!(slot_cap & PCI_EXP_SLTCAP_HPC))
+	if ((slot_cap == (u32)~0) || !(slot_cap & PCI_EXP_SLTCAP_HPC))
 		return false;
 
 	if (pcie_ports_native)
-- 
2.18.4


      parent reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-31 11:02 [PATCH v4 00/12] PCI: Remove '*val = 0' from pcie_capability_read_*() Saheed O. Bolarinwa
2020-07-31 11:02 ` [PATCH v4 01/12] IB/hfi1: Check if pcie_capability_read_*() reads ~0 Saheed O. Bolarinwa
2020-07-31 13:55   ` Bjorn Helgaas
2020-08-03 11:46     ` Ian Kumlien
2020-07-31 11:02 ` [PATCH v4 02/12] misc: rtsx: " Saheed O. Bolarinwa
2020-07-31 11:02 ` [PATCH v4 03/12] ath9k: " Saheed O. Bolarinwa
2020-07-31 11:02 ` [PATCH v4 04/12] iwlegacy: " Saheed O. Bolarinwa
2020-07-31 11:02 ` [PATCH v4 05/12] PCI: pciehp: Set "Power On" as the default get_power_status Saheed O. Bolarinwa
2020-07-31 11:02 ` [PATCH v4 06/12] PCI: pciehp: Check if pcie_capability_read_*() reads ~0 Saheed O. Bolarinwa
2020-07-31 11:02 ` Saheed O. Bolarinwa [this message]

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