[PATCH 1/2] ARM/PCI: bios32: Fix pcibios_init_resource() error return path

[PATCH 1/2] ARM/PCI: bios32: Fix pcibios_init_resource() error return path

[Lorenzo Pieralisi]

Since commit 97ad2bdcbe85 ("ARM/PCI: Convert PCI scan API to
pci_scan_root_bus_bridge()") struct pci_sys_data is allocated through
pci_alloc_host_bridge() which implies that, if pcibios_init_resource()
fails, the pci_sys_data should be freed along with struct pci_host_bridge
members through pci_free_host_bridge() instead of a simple kfree.

Fix commit 97ad2bdcbe85 ("ARM/PCI: Convert PCI scan API to
pci_scan_root_bus_bridge()") by updating pcibios_init_resource()
error path.

Fixes: 97ad2bdcbe85 ("ARM/PCI: Convert PCI scan API to pci_scan_root_bus_bridge()")
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Jason Cooper <jason@lakedaemon.net>
CC: Bjorn Helgaas <bhelgaas@google.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Andrew Lunn <andrew@lunn.ch>
---
 arch/arm/kernel/bios32.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
index 56dc1a3..c1809fb 100644
--- a/arch/arm/kernel/bios32.c
+++ b/arch/arm/kernel/bios32.c
@@ -480,7 +480,7 @@ static void pcibios_init_hw(struct device *parent, struct hw_pci *hw,
 
 			ret = pcibios_init_resource(nr, sys, hw->io_optional);
 			if (ret)  {
-				kfree(sys);
+				pci_free_host_bridge(bridge);
 				break;
 			}
 
-- 
2.10.0

[PATCH 2/2] MIPS/PCI: Fix pcibios_scan_bus() NULL check code path

[Lorenzo Pieralisi]

If pci_scan_root_bus() fails (ie returns NULL) pcibios_scan_bus() must
return immediately since the struct pci_bus pointer it returns is not
valid and cannot be used.

Move code checking the pci_scan_root_bus() return value to reinstate
proper pcibios_scanbus() error path behaviour.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
---
 arch/mips/pci/pci-legacy.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/mips/pci/pci-legacy.c b/arch/mips/pci/pci-legacy.c
index 174575a..71d62f8 100644
--- a/arch/mips/pci/pci-legacy.c
+++ b/arch/mips/pci/pci-legacy.c
@@ -89,16 +89,16 @@ static void pcibios_scanbus(struct pci_controller *hose)
 	pci_add_resource(&resources, hose->busn_resource);
 	bus = pci_scan_root_bus(NULL, next_busno, hose->pci_ops, hose,
 				&resources);
-	hose->bus = bus;
-
-	need_domain_info = need_domain_info || pci_domain_nr(bus);
-	set_pci_need_domain_info(hose, need_domain_info);
-
 	if (!bus) {
 		pci_free_resource_list(&resources);
 		return;
 	}
 
+	hose->bus = bus;
+
+	need_domain_info = need_domain_info || pci_domain_nr(bus);
+	set_pci_need_domain_info(hose, need_domain_info);
+
 	next_busno = bus->busn_res.end + 1;
 	/* Don't allow 8-bit bus number overflow inside the hose -
 	   reserve some space for bridges. */
-- 
2.10.0

Re: [PATCH 2/2] MIPS/PCI: Fix pcibios_scan_bus() NULL check code path

[Bjorn Helgaas]

On Mon, Jul 10, 2017 at 01:34:09PM +0100, Lorenzo Pieralisi wrote:
> If pci_scan_root_bus() fails (ie returns NULL) pcibios_scan_bus() must
> return immediately since the struct pci_bus pointer it returns is not
> valid and cannot be used.
> 
> Move code checking the pci_scan_root_bus() return value to reinstate
> proper pcibios_scanbus() error path behaviour.
> 
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Ralf Baechle <ralf@linux-mips.org>
> Cc: Paul Burton <paul.burton@imgtec.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>

I agree this is certainly broken.  In fact, I think I broke it with
9e808eb6a768 ("PCI: Cleanup control flow") in 2015.  So probably v4.14
material?

> ---
>  arch/mips/pci/pci-legacy.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/mips/pci/pci-legacy.c b/arch/mips/pci/pci-legacy.c
> index 174575a..71d62f8 100644
> --- a/arch/mips/pci/pci-legacy.c
> +++ b/arch/mips/pci/pci-legacy.c
> @@ -89,16 +89,16 @@ static void pcibios_scanbus(struct pci_controller *hose)
>  	pci_add_resource(&resources, hose->busn_resource);
>  	bus = pci_scan_root_bus(NULL, next_busno, hose->pci_ops, hose,
>  				&resources);
> -	hose->bus = bus;
> -
> -	need_domain_info = need_domain_info || pci_domain_nr(bus);
> -	set_pci_need_domain_info(hose, need_domain_info);
> -
>  	if (!bus) {
>  		pci_free_resource_list(&resources);
>  		return;
>  	}
>  
> +	hose->bus = bus;
> +
> +	need_domain_info = need_domain_info || pci_domain_nr(bus);
> +	set_pci_need_domain_info(hose, need_domain_info);
> +
>  	next_busno = bus->busn_res.end + 1;
>  	/* Don't allow 8-bit bus number overflow inside the hose -
>  	   reserve some space for bridges. */
> -- 
> 2.10.0
> 

Re: [PATCH 2/2] MIPS/PCI: Fix pcibios_scan_bus() NULL check code path

[Lorenzo Pieralisi]

On Mon, Jul 10, 2017 at 09:55:53AM -0500, Bjorn Helgaas wrote:
> On Mon, Jul 10, 2017 at 01:34:09PM +0100, Lorenzo Pieralisi wrote:
> > If pci_scan_root_bus() fails (ie returns NULL) pcibios_scan_bus() must
> > return immediately since the struct pci_bus pointer it returns is not
> > valid and cannot be used.
> > 
> > Move code checking the pci_scan_root_bus() return value to reinstate
> > proper pcibios_scanbus() error path behaviour.
> > 
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > Cc: Ralf Baechle <ralf@linux-mips.org>
> > Cc: Paul Burton <paul.burton@imgtec.com>
> > Cc: Bjorn Helgaas <bhelgaas@google.com>
> 
> I agree this is certainly broken.  In fact, I think I broke it with
> 9e808eb6a768 ("PCI: Cleanup control flow") in 2015.  So probably v4.14
> material?

Yes that makes sense, I spotted it since I am preparing patches to
remove pci_fixup_irqs() from the kernel (by removing it from all arches
that still use it), I think that technically:

88555b481958 ("MIPS: PCI: Support for CONFIG_PCI_DOMAINS_GENERIC")

created a possible breakage (ie by using the possible NULL bus pointer),
if you merge it in one branch for 4.14 I will base the pci_fixup_irqs()
removal on top of it and post the series, just let me know please.

Thanks !
Lorenzo

> > ---
> >  arch/mips/pci/pci-legacy.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> > 
> > diff --git a/arch/mips/pci/pci-legacy.c b/arch/mips/pci/pci-legacy.c
> > index 174575a..71d62f8 100644
> > --- a/arch/mips/pci/pci-legacy.c
> > +++ b/arch/mips/pci/pci-legacy.c
> > @@ -89,16 +89,16 @@ static void pcibios_scanbus(struct pci_controller *hose)
> >  	pci_add_resource(&resources, hose->busn_resource);
> >  	bus = pci_scan_root_bus(NULL, next_busno, hose->pci_ops, hose,
> >  				&resources);
> > -	hose->bus = bus;
> > -
> > -	need_domain_info = need_domain_info || pci_domain_nr(bus);
> > -	set_pci_need_domain_info(hose, need_domain_info);
> > -
> >  	if (!bus) {
> >  		pci_free_resource_list(&resources);
> >  		return;
> >  	}
> >  
> > +	hose->bus = bus;
> > +
> > +	need_domain_info = need_domain_info || pci_domain_nr(bus);
> > +	set_pci_need_domain_info(hose, need_domain_info);
> > +
> >  	next_busno = bus->busn_res.end + 1;
> >  	/* Don't allow 8-bit bus number overflow inside the hose -
> >  	   reserve some space for bridges. */
> > -- 
> > 2.10.0
> > 

Re: [PATCH 2/2] MIPS/PCI: Fix pcibios_scan_bus() NULL check code path

[Bjorn Helgaas]

On Mon, Jul 10, 2017 at 04:49:24PM +0100, Lorenzo Pieralisi wrote:
> On Mon, Jul 10, 2017 at 09:55:53AM -0500, Bjorn Helgaas wrote:
> > On Mon, Jul 10, 2017 at 01:34:09PM +0100, Lorenzo Pieralisi wrote:
> > > If pci_scan_root_bus() fails (ie returns NULL) pcibios_scan_bus() must
> > > return immediately since the struct pci_bus pointer it returns is not
> > > valid and cannot be used.
> > > 
> > > Move code checking the pci_scan_root_bus() return value to reinstate
> > > proper pcibios_scanbus() error path behaviour.
> > > 
> > > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > > Cc: Ralf Baechle <ralf@linux-mips.org>
> > > Cc: Paul Burton <paul.burton@imgtec.com>
> > > Cc: Bjorn Helgaas <bhelgaas@google.com>
> > 
> > I agree this is certainly broken.  In fact, I think I broke it with
> > 9e808eb6a768 ("PCI: Cleanup control flow") in 2015.  So probably v4.14
> > material?
> 
> Yes that makes sense, I spotted it since I am preparing patches to
> remove pci_fixup_irqs() from the kernel (by removing it from all arches
> that still use it), I think that technically:
> 
> 88555b481958 ("MIPS: PCI: Support for CONFIG_PCI_DOMAINS_GENERIC")
> 
> created a possible breakage (ie by using the possible NULL bus pointer),
> if you merge it in one branch for 4.14 I will base the pci_fixup_irqs()
> removal on top of it and post the series, just let me know please.

Ah, you're right.  I created some poor style (checking the return
value after intervening code) with 9e808eb6a768, and then 88555b481958
fell into the trap I had laid.

I put this on pci/irq-fixups for a continuation of your work and
started it off with this patch.

I will rebase the branch after -rc1, but that shouldn't be a problem
for you because I normally apply patches from email rather than
pulling them directly.  I'll be on vacation July 14-28, so that
probably won't happen until August.

Thanks!

> > > ---
> > >  arch/mips/pci/pci-legacy.c | 10 +++++-----
> > >  1 file changed, 5 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/arch/mips/pci/pci-legacy.c b/arch/mips/pci/pci-legacy.c
> > > index 174575a..71d62f8 100644
> > > --- a/arch/mips/pci/pci-legacy.c
> > > +++ b/arch/mips/pci/pci-legacy.c
> > > @@ -89,16 +89,16 @@ static void pcibios_scanbus(struct pci_controller *hose)
> > >  	pci_add_resource(&resources, hose->busn_resource);
> > >  	bus = pci_scan_root_bus(NULL, next_busno, hose->pci_ops, hose,
> > >  				&resources);
> > > -	hose->bus = bus;
> > > -
> > > -	need_domain_info = need_domain_info || pci_domain_nr(bus);
> > > -	set_pci_need_domain_info(hose, need_domain_info);
> > > -
> > >  	if (!bus) {
> > >  		pci_free_resource_list(&resources);
> > >  		return;
> > >  	}
> > >  
> > > +	hose->bus = bus;
> > > +
> > > +	need_domain_info = need_domain_info || pci_domain_nr(bus);
> > > +	set_pci_need_domain_info(hose, need_domain_info);
> > > +
> > >  	next_busno = bus->busn_res.end + 1;
> > >  	/* Don't allow 8-bit bus number overflow inside the hose -
> > >  	   reserve some space for bridges. */
> > > -- 
> > > 2.10.0
> > > 

Re: [PATCH 1/2] ARM/PCI: bios32: Fix pcibios_init_resource() error return path

[Bjorn Helgaas]

On Mon, Jul 10, 2017 at 01:34:08PM +0100, Lorenzo Pieralisi wrote:
> Since commit 97ad2bdcbe85 ("ARM/PCI: Convert PCI scan API to
> pci_scan_root_bus_bridge()") struct pci_sys_data is allocated through
> pci_alloc_host_bridge() which implies that, if pcibios_init_resource()
> fails, the pci_sys_data should be freed along with struct pci_host_bridge
> members through pci_free_host_bridge() instead of a simple kfree.
> 
> Fix commit 97ad2bdcbe85 ("ARM/PCI: Convert PCI scan API to
> pci_scan_root_bus_bridge()") by updating pcibios_init_resource()
> error path.
> 
> Fixes: 97ad2bdcbe85 ("ARM/PCI: Convert PCI scan API to pci_scan_root_bus_bridge()")
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Jason Cooper <jason@lakedaemon.net>
> CC: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Andrew Lunn <andrew@lunn.ch>

Applied to for-linus for v4.13, thanks!

> ---
>  arch/arm/kernel/bios32.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
> index 56dc1a3..c1809fb 100644
> --- a/arch/arm/kernel/bios32.c
> +++ b/arch/arm/kernel/bios32.c
> @@ -480,7 +480,7 @@ static void pcibios_init_hw(struct device *parent, struct hw_pci *hw,
>  
>  			ret = pcibios_init_resource(nr, sys, hw->io_optional);
>  			if (ret)  {
> -				kfree(sys);
> +				pci_free_host_bridge(bridge);
>  				break;
>  			}
>  
> -- 
> 2.10.0
>