[PATCH] PCI: pciehp_core, fix lock imbalance

[PATCH] PCI: pciehp_core, fix lock imbalance

[Jiri Slaby]

set_lock_status omits mutex_unlock in fail path. Add the omitted
unlock.

As a result a lockup caused by this can be triggered from userspace
by writing 1 to /sys/bus/pci/slots/.../lock often enough.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
---
 drivers/pci/hotplug/pciehp_core.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
index 5482d4e..c248554 100644
--- a/drivers/pci/hotplug/pciehp_core.c
+++ b/drivers/pci/hotplug/pciehp_core.c
@@ -126,8 +126,10 @@ static int set_lock_status(struct hotplug_slot *hotplug_slot, u8 status)
 	mutex_lock(&slot->ctrl->crit_sect);
 
 	/* has it been >1 sec since our last toggle? */
-	if ((get_seconds() - slot->last_emi_toggle) < 1)
+	if ((get_seconds() - slot->last_emi_toggle) < 1) {
+		mutex_unlock(&slot->ctrl->crit_sect);
 		return -EINVAL;
+	}
 
 	/* see what our current state is */
 	retval = get_lock_status(hotplug_slot, &value);
-- 
1.6.1
caught by stanse

Re: [PATCH] PCI: pciehp_core, fix lock imbalance

[Kenji Kaneshige]

Jiri Slaby wrote:
> set_lock_status omits mutex_unlock in fail path. Add the omitted
> unlock.
> 
> As a result a lockup caused by this can be triggered from userspace
> by writing 1 to /sys/bus/pci/slots/.../lock often enough.
> 
> Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
> Cc: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
> Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> ---
>  drivers/pci/hotplug/pciehp_core.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
> index 5482d4e..c248554 100644
> --- a/drivers/pci/hotplug/pciehp_core.c
> +++ b/drivers/pci/hotplug/pciehp_core.c
> @@ -126,8 +126,10 @@ static int set_lock_status(struct hotplug_slot *hotplug_slot, u8 status)
>  	mutex_lock(&slot->ctrl->crit_sect);
>  
>  	/* has it been >1 sec since our last toggle? */
> -	if ((get_seconds() - slot->last_emi_toggle) < 1)
> +	if ((get_seconds() - slot->last_emi_toggle) < 1) {
> +		mutex_unlock(&slot->ctrl->crit_sect);
>  		return -EINVAL;
> +	}
>  
>  	/* see what our current state is */
>  	retval = get_lock_status(hotplug_slot, &value);

Good catch!

Reviewed-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>

Thanks,
Kenji Kaneshige

Re: [PATCH] PCI: pciehp_core, fix lock imbalance

[Jesse Barnes]

On Saturday, January 17, 2009 7:23 am Jiri Slaby wrote:
> set_lock_status omits mutex_unlock in fail path. Add the omitted
> unlock.
>
> As a result a lockup caused by this can be triggered from userspace
> by writing 1 to /sys/bus/pci/slots/.../lock often enough.
>
> Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
> Cc: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
> Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> ---
>  drivers/pci/hotplug/pciehp_core.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/pci/hotplug/pciehp_core.c
> b/drivers/pci/hotplug/pciehp_core.c index 5482d4e..c248554 100644
> --- a/drivers/pci/hotplug/pciehp_core.c
> +++ b/drivers/pci/hotplug/pciehp_core.c
> @@ -126,8 +126,10 @@ static int set_lock_status(struct hotplug_slot
> *hotplug_slot, u8 status) mutex_lock(&slot->ctrl->crit_sect);
>
>  	/* has it been >1 sec since our last toggle? */
> -	if ((get_seconds() - slot->last_emi_toggle) < 1)
> +	if ((get_seconds() - slot->last_emi_toggle) < 1) {
> +		mutex_unlock(&slot->ctrl->crit_sect);
>  		return -EINVAL;
> +	}
>
>  	/* see what our current state is */
>  	retval = get_lock_status(hotplug_slot, &value);

Applied to my for-linus branch (with Kenji-san's reviewed-by), thanks.

-- 
Jesse Barnes, Intel Open Source Technology Center