linux-kernel - [PATCH AUTOSEL 6.6 03/18] powerpc/eeh: avoid possible crash when edev->pdev changes

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Message-ID: <20240716142713.2712998-3-sashal@kernel.org>
Date: Tue, 16 Jul 2024 10:26:38 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Ganesh Goudar <ganeshgr@...ux.ibm.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Sasha Levin <sashal@...nel.org>,
	mahesh@...ux.ibm.com,
	linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH AUTOSEL 6.6 03/18] powerpc/eeh: avoid possible crash when edev->pdev changes

From: Ganesh Goudar <ganeshgr@...ux.ibm.com>

[ Upstream commit a1216e62d039bf63a539bbe718536ec789a853dd ]

If a PCI device is removed during eeh_pe_report_edev(), edev->pdev
will change and can cause a crash, hold the PCI rescan/remove lock
while taking a copy of edev->pdev->bus.

Signed-off-by: Ganesh Goudar <ganeshgr@...ux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Link: https://msgid.link/20240617140240.580453-1-ganeshgr@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/powerpc/kernel/eeh_pe.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/eeh_pe.c b/arch/powerpc/kernel/eeh_pe.c
index e0ce812796241..7d1b50599dd6c 100644
--- a/arch/powerpc/kernel/eeh_pe.c
+++ b/arch/powerpc/kernel/eeh_pe.c
@@ -849,6 +849,7 @@ struct pci_bus *eeh_pe_bus_get(struct eeh_pe *pe)
 {
 	struct eeh_dev *edev;
 	struct pci_dev *pdev;
+	struct pci_bus *bus = NULL;
 
 	if (pe->type & EEH_PE_PHB)
 		return pe->phb->bus;
@@ -859,9 +860,11 @@ struct pci_bus *eeh_pe_bus_get(struct eeh_pe *pe)
 
 	/* Retrieve the parent PCI bus of first (top) PCI device */
 	edev = list_first_entry_or_null(&pe->edevs, struct eeh_dev, entry);
+	pci_lock_rescan_remove();
 	pdev = eeh_dev_to_pci_dev(edev);
 	if (pdev)
-		return pdev->bus;
+		bus = pdev->bus;
+	pci_unlock_rescan_remove();
 
-	return NULL;
+	return bus;
 }
-- 
2.43.0