linux-kernel - [PATCH 12/14 v3] PCI/AER: Check the return value of pcie_capability_read

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Date:   Mon, 13 Jul 2020 19:55:29 +0200
From:   "Saheed O. Bolarinwa" <refactormyself@...il.com>
To:     skhan@...uxfoundation.org, linux-pci@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-kernel@...r.kernel.org
Cc:     Bolarinwa Olayemi Saheed <refactormyself@...il.com>
Subject: [PATCH 12/14 v3] PCI/AER: Check the return value of pcie_capability_read_*()

From: Bolarinwa Olayemi Saheed <refactormyself@...il.com>

On failure pcie_capability_read_dword() sets it's last parameter,
val to 0.
However, with Patch 14/14, it is possible that val is set to ~0 on
failure. This would introduce a bug because (x & x) == (~0 & x).

This bug can be avoided if the return value of pcie_capability_read_word
is checked to confirm success.

Check the return value of pcie_capability_read_word() to ensure success.

Suggested-by: Bjorn Helgaas <bjorn@...gaas.com>
Signed-off-by: Bolarinwa Olayemi Saheed <refactormyself@...il.com>
---
 drivers/pci/pcie/aer.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 3acf56683915..f4beb47c622c 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -800,6 +800,7 @@ static bool is_error_source(struct pci_dev *dev, struct aer_err_info *e_info)
 	int aer = dev->aer_cap;
 	u32 status, mask;
 	u16 reg16;
+	int ret;
 
 	/*
 	 * When bus id is equal to 0, it might be a bad id
@@ -828,8 +829,8 @@ static bool is_error_source(struct pci_dev *dev, struct aer_err_info *e_info)
 		return false;
 
 	/* Check if AER is enabled */
-	pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &reg16);
-	if (!(reg16 & PCI_EXP_AER_FLAGS))
+	ret = pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &reg16);
+	if (ret || !(reg16 & PCI_EXP_AER_FLAGS))
 		return false;
 
 	if (!aer)
-- 
2.18.2