When device_register(&child->dev) failed, calling put_device() to explicitly release child->dev. Otherwise, it could cause double free problem.
Found by code review.
Cc: stable@vger.kernel.org Fixes: 4f535093cf8f ("PCI: Put pci_dev in device tree as early as possible") Signed-off-by: Ma Ke make_ruc2021@163.com --- drivers/pci/probe.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 2e81ab0f5a25..d3146c588d7f 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1174,7 +1174,10 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent, add_dev: pci_set_bus_msi_domain(child); ret = device_register(&child->dev); - WARN_ON(ret < 0); + if (ret) { + WARN_ON(ret < 0); + put_device(&child->dev); + }
pcibios_add_bus(child);
On Tue, 17 Dec 2024, Ma Ke wrote:
When device_register(&child->dev) failed, calling put_device() to explicitly release child->dev. Otherwise, it could cause double free problem.
Found by code review.
Cc: stable@vger.kernel.org Fixes: 4f535093cf8f ("PCI: Put pci_dev in device tree as early as possible") Signed-off-by: Ma Ke make_ruc2021@163.com
drivers/pci/probe.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 2e81ab0f5a25..d3146c588d7f 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1174,7 +1174,10 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent, add_dev: pci_set_bus_msi_domain(child); ret = device_register(&child->dev);
- WARN_ON(ret < 0);
- if (ret) {
WARN_ON(ret < 0);
The usual way is:
if (WARN_ON(ret < 0))
put_device(&child->dev);- }
pcibios_add_bus(child);
But more serious problem here is that should this code even proceed as if nothing happened when an error occurs? pci_register_host_bridge() does proper rollback when device_register() fails but this function doesn't.
Into the same vein, is using WARN_ON() even correct here? Why should this print a stacktrace if device_register() fails instead of simply printing and error?
Ilpo Järvinenilpo.jarvinen@linux.intel.com wrote:
Ma Ke make_ruc2021@163.com writes:
When device_register(&child->dev) failed, calling put_device() to explicitly release child->dev. Otherwise, it could cause double free problem.
Found by code review.
Cc: stable@vger.kernel.org Fixes: 4f535093cf8f ("PCI: Put pci_dev in device tree as early as possible") Signed-off-by: Ma Ke make_ruc2021@163.com
drivers/pci/probe.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 2e81ab0f5a25..d3146c588d7f 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1174,7 +1174,10 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent, add_dev: pci_set_bus_msi_domain(child); ret = device_register(&child->dev);
- WARN_ON(ret < 0);
- if (ret) {
WARN_ON(ret < 0);The usual way is:
if (WARN_ON(ret < 0))
put_device(&child->dev);- }
pcibios_add_bus(child);
But more serious problem here is that should this code even proceed as if nothing happened when an error occurs? pci_register_host_bridge() does proper rollback when device_register() fails but this function doesn't.
Into the same vein, is using WARN_ON() even correct here? Why should this print a stacktrace if device_register() fails instead of simply printing and error?
Thank you for your guidance and suggestions. I have the same confusion about the simple handling(WARN_ON()) of errors if device_add() fails. I am looking forward to receiving guidance and insights from other experts.
-- Regards,
Ma Ke
linux-stable-mirror@lists.linaro.org
-
Ilpo Järvinen -
Ma Ke