From f9bc28aedfb5bbd572d2d365f3095c1becd7209b Mon Sep 17 00:00:00 2001
From: Sam Bobroff <sbobroff@linux.ibm.com>
Date: Wed, 12 Sep 2018 11:23:20 +1000
Subject: [PATCH] powerpc/eeh: Fix possible null deref in eeh_dump_dev_log()

References: bsc#1065729
Patch-mainline: v4.20-rc1
Git-commit: f9bc28aedfb5bbd572d2d365f3095c1becd7209b

If an error occurs during an unplug operation, it's possible for
eeh_dump_dev_log() to be called when edev->pdn is null, which
currently leads to dereferencing a null pointer.

Handle this by skipping the error log for those devices.

Signed-off-by: Sam Bobroff <sbobroff@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/kernel/eeh.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
--- a/arch/powerpc/kernel/eeh.c
+++ b/arch/powerpc/kernel/eeh.c
@@ -169,6 +169,11 @@ static size_t eeh_dump_dev_log(struct eeh_dev *edev, char *buf, size_t len)
 	int n = 0, l = 0;
 	char buffer[128];
 
+	if (!pdn) {
+		pr_warn("EEH: Note: No error log for absent device.\n");
+		return 0;
+	}
+
 	n += scnprintf(buf+n, len-n, "%04x:%02x:%02x.%01x\n",
 		       edev->phb->global_number, pdn->busno,
 		       PCI_SLOT(pdn->devfn), PCI_FUNC(pdn->devfn));
-- 
2.35.3