[PATCH AUTOSEL 4.9 04/21] powerpc/eeh: Fix possible null deref in eeh_dump_dev_log()

From: Sasha Levin
Date: Sun Nov 04 2018 - 08:54:06 EST


From: Sam Bobroff <sbobroff@xxxxxxxxxxxxx>

[ Upstream 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@xxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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
index e5bfbf62827a..8336b9016ca9 100644
--- 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));
--
2.17.1