This is a note to let you know that I've just added the patch titled
PCI: Allow a NULL "parent" pointer in pci_bus_assign_domain_nr()
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pci-allow-a-null-parent-pointer-in-pci_bus_assign_domain_nr.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 54c6e2dd00c313d0add58e5befe62fe6f286d03b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krzysztof=20=3D=3Futf-8=3FQ=3FHa=3DC5=3D82asa=3F=3D?=
<khalasa@xxxxxxx>
Date: Tue, 1 Mar 2016 07:07:18 +0100
Subject: PCI: Allow a NULL "parent" pointer in pci_bus_assign_domain_nr()
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From: Krzysztof =?utf-8?Q?Ha=C5=82asa?= <khalasa@xxxxxxx>
commit 54c6e2dd00c313d0add58e5befe62fe6f286d03b upstream.
pci_create_root_bus() passes a "parent" pointer to
pci_bus_assign_domain_nr(). When CONFIG_PCI_DOMAINS_GENERIC is defined,
pci_bus_assign_domain_nr() dereferences that pointer. Many callers of
pci_create_root_bus() supply a NULL "parent" pointer, which leads to a NULL
pointer dereference error.
7c674700098c ("PCI: Move domain assignment from arm64 to generic code")
moved the "parent" dereference from arm64 to generic code. Only arm64 used
that code (because only arm64 defined CONFIG_PCI_DOMAINS_GENERIC), and it
always supplied a valid "parent" pointer. Other arches supplied NULL
"parent" pointers but didn't defined CONFIG_PCI_DOMAINS_GENERIC, so they
used a no-op version of pci_bus_assign_domain_nr().
8c7d14746abc ("ARM/PCI: Move to generic PCI domains") defined
CONFIG_PCI_DOMAINS_GENERIC on ARM, and many ARM platforms use
pci_common_init(), which supplies a NULL "parent" pointer.
These platforms (cns3xxx, dove, footbridge, iop13xx, etc.) crash
with a NULL pointer dereference like this while probing PCI:
Unable to handle kernel NULL pointer dereference at virtual address 000000a4
PC is at pci_bus_assign_domain_nr+0x10/0x84
LR is at pci_create_root_bus+0x48/0x2e4
Kernel panic - not syncing: Attempted to kill init!
[bhelgaas: changelog, add "Reported:" and "Fixes:" tags]
Reported: http://forum.doozan.com/read.php?2,17868,22070,quote=1
Fixes: 8c7d14746abc ("ARM/PCI: Move to generic PCI domains")
Fixes: 7c674700098c ("PCI: Move domain assignment from arm64 to generic code")
Signed-off-by: Krzysztof Hałasa <khalasa@xxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/pci/pci.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4772,8 +4772,10 @@ int pci_get_new_domain_nr(void)
void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent)
{
static int use_dt_domains = -1;
- int domain = of_get_pci_domain_nr(parent->of_node);
+ int domain = -1;
+ if (parent)
+ domain = of_get_pci_domain_nr(parent->of_node);
/*
* Check DT domain and use_dt_domains values.
*
Patches currently in stable-queue which might be from khalasa@xxxxxxx are
queue-4.4/pci-allow-a-null-parent-pointer-in-pci_bus_assign_domain_nr.patch
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