All of entries are freed in a loop, however, the freed entry is accessed by list_del() after the loop.
When epf driver that includes pci-epf-test unload, the pci_epf_remove_cfs() is called, and occurred the use after free. Therefore, kernel panics randomly after or while the module unloading.
I tested this patch with r8a77951-Salvator-xs boards.
Fixes: ef1433f ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry") Signed-off-by: Shunsuke Mie mie@igel.co.jp --- drivers/pci/endpoint/pci-epf-core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c index e9289d10f822..538e902b0ba6 100644 --- a/drivers/pci/endpoint/pci-epf-core.c +++ b/drivers/pci/endpoint/pci-epf-core.c @@ -202,8 +202,10 @@ static void pci_epf_remove_cfs(struct pci_epf_driver *driver) return;
mutex_lock(&pci_epf_mutex); - list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) + list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) { + list_del(&group->group_entry); pci_ep_cfs_remove_epf_group(group); + } list_del(&driver->epf_group); mutex_unlock(&pci_epf_mutex); }
On Mon, Jun 21, 2021 at 04:00:58PM +0900, Shunsuke Mie wrote:
All of entries are freed in a loop, however, the freed entry is accessed by list_del() after the loop.
When epf driver that includes pci-epf-test unload, the pci_epf_remove_cfs() is called, and occurred the use after free. Therefore, kernel panics randomly after or while the module unloading.
I tested this patch with r8a77951-Salvator-xs boards.
Fixes: ef1433f ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry") Signed-off-by: Shunsuke Mie mie@igel.co.jp
drivers/pci/endpoint/pci-epf-core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
<formletter>
This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.
</formletter>
Hi Shunsuke,
On 21/06/21 12:30 pm, Shunsuke Mie wrote:
All of entries are freed in a loop, however, the freed entry is accessed by list_del() after the loop.
When epf driver that includes pci-epf-test unload, the pci_epf_remove_cfs() is called, and occurred the use after free. Therefore, kernel panics randomly after or while the module unloading.
I tested this patch with r8a77951-Salvator-xs boards.
Can you provide the crash dump?
Fixes: ef1433f ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry") Signed-off-by: Shunsuke Mie mie@igel.co.jp
drivers/pci/endpoint/pci-epf-core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c index e9289d10f822..538e902b0ba6 100644 --- a/drivers/pci/endpoint/pci-epf-core.c +++ b/drivers/pci/endpoint/pci-epf-core.c @@ -202,8 +202,10 @@ static void pci_epf_remove_cfs(struct pci_epf_driver *driver) return; mutex_lock(&pci_epf_mutex);
- list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry)
- list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) {
list_del(&group->group_entry);
Need full crash dump to see if this is really required or not. Ideally this should be handled by configfs (or a configfs API could be used).
Thanks, Kishon
Hi Kishon,
2021年12月7日(火) 16:26 Kishon Vijay Abraham I kishon@ti.com:
Hi Shunsuke,
On 21/06/21 12:30 pm, Shunsuke Mie wrote:
All of entries are freed in a loop, however, the freed entry is accessed by list_del() after the loop.
When epf driver that includes pci-epf-test unload, the pci_epf_remove_cfs() is called, and occurred the use after free. Therefore, kernel panics randomly after or while the module unloading.
I tested this patch with r8a77951-Salvator-xs boards.
Can you provide the crash dump?
Ok. However, that is use-after-free bug. so, the crash log is changed randomly. I'll send some crash dumps.
Fixes: ef1433f ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry") Signed-off-by: Shunsuke Mie mie@igel.co.jp
drivers/pci/endpoint/pci-epf-core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c index e9289d10f822..538e902b0ba6 100644 --- a/drivers/pci/endpoint/pci-epf-core.c +++ b/drivers/pci/endpoint/pci-epf-core.c @@ -202,8 +202,10 @@ static void pci_epf_remove_cfs(struct pci_epf_driver *driver) return;
mutex_lock(&pci_epf_mutex);
list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry)
list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) {list_del(&group->group_entry);Need full crash dump to see if this is really required or not. Ideally this should be handled by configfs (or a configfs API could be used).
Thanks, Kishon
Hi Kishon,
This is the crash log. I think you can reproduce this problem by loading and unloading the pci-epf-test modules some times, but I don't think you'll see similar logs in your environment.
The pci_ep_cfs_remove_epf_group function calls kfree for the `group`, however a member of group, `group_entry``, is accessed by a list_del() after the loop. The patch changes to remove list entries to prevent the accessing after freed object.
Thanks, Shunsuke
2021年12月7日(火) 16:44 Shunsuke Mie mie@igel.co.jp:
Hi Kishon,
2021年12月7日(火) 16:26 Kishon Vijay Abraham I kishon@ti.com:
Hi Shunsuke,
On 21/06/21 12:30 pm, Shunsuke Mie wrote:
All of entries are freed in a loop, however, the freed entry is accessed by list_del() after the loop.
When epf driver that includes pci-epf-test unload, the pci_epf_remove_cfs() is called, and occurred the use after free. Therefore, kernel panics randomly after or while the module unloading.
I tested this patch with r8a77951-Salvator-xs boards.
Can you provide the crash dump?
Ok. However, that is use-after-free bug. so, the crash log is changed randomly. I'll send some crash dumps.
Fixes: ef1433f ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry") Signed-off-by: Shunsuke Mie mie@igel.co.jp
drivers/pci/endpoint/pci-epf-core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c index e9289d10f822..538e902b0ba6 100644 --- a/drivers/pci/endpoint/pci-epf-core.c +++ b/drivers/pci/endpoint/pci-epf-core.c @@ -202,8 +202,10 @@ static void pci_epf_remove_cfs(struct pci_epf_driver *driver) return;
mutex_lock(&pci_epf_mutex);
list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry)
list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) {list_del(&group->group_entry);Need full crash dump to see if this is really required or not. Ideally this should be handled by configfs (or a configfs API could be used).
Thanks, Kishon
linux-stable-mirror@lists.linaro.org
-
Greg KH -
Kishon Vijay Abraham I -
Shunsuke Mie