[PATCH 1/1] PCI: xen-pcifront, fix PCI reference leak

[PATCH 1/1] PCI: xen-pcifront, fix PCI reference leak

[Jiri Slaby]

Stanse found that when pdev is found and has no driver a reference is
leaked in pcifront_common_process. So add pci_dev_put there. For the
pdev == NULL case, pci_dev_put(NULL) is fine.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
---
 drivers/pci/xen-pcifront.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index a87c498..f9ffc05 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -578,6 +578,7 @@ static pci_ers_result_t pcifront_common_process(int cmd,
 	if (!pcidev || !pcidev->driver) {
 		dev_err(&pcidev->dev,
 			"device or driver is NULL\n");
+		pci_dev_put(pcidev);
 		return result;
 	}
 	pdrv = pcidev->driver;
-- 
1.7.3.1

Re: [PATCH 1/1] PCI: xen-pcifront, fix PCI reference leak

[Milton Miller]

On 2010-11-04 at about 14:31:30 Jiri Slaby wrote:
> Stanse found that when pdev is found and has no driver a reference is
> leaked in pcifront_common_process. So add pci_dev_put there. For the
> pdev == NULL case, pci_dev_put(NULL) is fine.

While that may be true, the dev_err(&pcidev->dev ... is a NULL pointer
deref.

> 
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> ---
>  drivers/pci/xen-pcifront.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
> index a87c498..f9ffc05 100644
> --- a/drivers/pci/xen-pcifront.c
> +++ b/drivers/pci/xen-pcifront.c
> @@ -578,6 +578,7 @@  static pci_ers_result_t pcifront_common_process(int cmd,
>  	if (!pcidev || !pcidev->driver) {
>  		dev_err(&pcidev->dev,
>  			"device or driver is NULL\n");
> +		pci_dev_put(pcidev);
>  		return result;
>  	}
>  	pdrv = pcidev->driver;
> 

milton

Re: [PATCH 1/1] PCI: xen-pcifront, fix PCI reference leak

[Konrad Rzeszutek Wilk]

On Thu, Nov 04, 2010 at 12:27:07PM -0600, Milton Miller wrote:
> On 2010-11-04 at about 14:31:30 Jiri Slaby wrote:
> > Stanse found that when pdev is found and has no driver a reference is
> > leaked in pcifront_common_process. So add pci_dev_put there. For the
> > pdev == NULL case, pci_dev_put(NULL) is fine.
> 
> While that may be true, the dev_err(&pcidev->dev ... is a NULL pointer
> deref.

I've put the fix in the branch (stable/xen-pcifront-fixes) that I will ask Linus
to pull.. but what options did you need to find this?

I tried to run this before putting your and Milton fix in:
konrad@phenom:~/tar/stanse-1.1.2$ java -jar ./stanse.jar  ~/work/linux/drivers/pci/xen-pcifront.c 
Stanse version "1.1.2"
Copyright (c) 2008-2010 Masaryk University, Brno

STANSE_HOME not specified. Using the location of stanse.jar.
Checking for bugs:
<-> File: /home/konrad/work/linux/drivers/pci/xen-pcifront.c
<-> --------------------------------
Done.

And no warnings?

Re: [PATCH 1/1] PCI: xen-pcifront, fix PCI reference leak

[Jiri Slaby]

On 11/08/2010 05:34 PM, Konrad Rzeszutek Wilk wrote:
> On Thu, Nov 04, 2010 at 12:27:07PM -0600, Milton Miller wrote:
>> On 2010-11-04 at about 14:31:30 Jiri Slaby wrote:
>>> Stanse found that when pdev is found and has no driver a reference is
>>> leaked in pcifront_common_process. So add pci_dev_put there. For the
>>> pdev == NULL case, pci_dev_put(NULL) is fine.
>>
>> While that may be true, the dev_err(&pcidev->dev ... is a NULL pointer
>> deref.
> 
> I've put the fix in the branch (stable/xen-pcifront-fixes) that I will ask Linus
> to pull.. but what options did you need to find this?
> 
> I tried to run this before putting your and Milton fix in:
> konrad@phenom:~/tar/stanse-1.1.2$ java -jar ./stanse.jar  ~/work/linux/drivers/pci/xen-pcifront.c 
> Stanse version "1.1.2"
> Copyright (c) 2008-2010 Masaryk University, Brno
> 
> STANSE_HOME not specified. Using the location of stanse.jar.
> Checking for bugs:
> <-> File: /home/konrad/work/linux/drivers/pci/xen-pcifront.c
> <-> --------------------------------
> Done.
> 
> And no warnings?

It's not easy as that. You have to specify checkers like
-c
AutomatonChecker:dist/data/checkers/AutomatonChecker/kernel_pairing.xml
-c AutomatonChecker:dist/data/checkers/AutomatonChecker/kernel_memory.xml
etc. Then, probably stanse won't guess kernel build flags correctly, so
you need to utilize kernel make system. So the command-line (from linux
src dir) would be:
STANSE_HOME=PATH java -jar PATH/stanse.jar -c
AutomatonChecker:PATH/dist/data/checkers/AutomatonChecker/kernel_pairing.xml
-c
AutomatonChecker:PATH/dist/data/checkers/AutomatonChecker/kernel_memory.xml
--makefile Makefile --make-params 'drivers/pci/xen-pcifront.o'

Presumably drivers/pci/xen-pcifront.o must not exist so that when stanse
runs make, it actually builds something. It will warn you about that anyway.

Maybe you want to run with gui: -g to track the issues in gui. There you
can also add the checkers by hand (or on cmdline too).

For openSUSE, I package stanse into rpm, and there is a script which has
-k and adds all the kernel checkers by default.

regards,
-- 
js