[PATCH v3 0/2] Fix EPF configfs attribute group removal

[PATCH v3 0/2] Fix EPF configfs attribute group removal

[Damien Le Moal]

A couple of patches to fix removal of configfs attribute groups of a PCI
endpoint function driver.

Changes from v2:
 - Use list_del() instead of list_del_init() in patch 2
 - Added Niklas' review tags

Changes from v1:
 - Split out patch 1 from patch 2 as requested by Niklas.

Damien Le Moal (2):
  PCI: endpoint: Fix configfs group list head handling
  PCI: endpoint: Fix configfs group removal on driver teardown

 drivers/pci/endpoint/pci-ep-cfs.c   | 1 +
 drivers/pci/endpoint/pci-epf-core.c | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

-- 
2.49.0

[PATCH v3 1/2] PCI: endpoint: Fix configfs group list head handling

[Damien Le Moal]

Doing a list_del() on the epf_group field of struct pci_epf_driver in
pci_epf_remove_cfs() is not correct as this field is a list head, not
a list entry. This list_del() call triggers a KASAN warning when an
endpoint function driver which has a configfs attribute group is torn
down:

==================================================================
BUG: KASAN: slab-use-after-free in pci_epf_remove_cfs+0x17c/0x198
Write of size 8 at addr ffff00010f4a0d80 by task rmmod/319

CPU: 3 UID: 0 PID: 319 Comm: rmmod Not tainted 6.16.0-rc2 #1 NONE
Hardware name: Radxa ROCK 5B (DT)
Call trace:
show_stack+0x2c/0x84 (C)
dump_stack_lvl+0x70/0x98
print_report+0x17c/0x538
kasan_report+0xb8/0x190
__asan_report_store8_noabort+0x20/0x2c
pci_epf_remove_cfs+0x17c/0x198
pci_epf_unregister_driver+0x18/0x30
nvmet_pci_epf_cleanup_module+0x24/0x30 [nvmet_pci_epf]
__arm64_sys_delete_module+0x264/0x424
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xac/0x230
do_el0_svc+0x40/0x58
el0_svc+0x48/0xdc
el0t_64_sync_handler+0x10c/0x138
el0t_64_sync+0x198/0x19c
...

Remove this incorrect list_del() call from pci_epf_remove_cfs().

Fixes: ef1433f717a2 ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/endpoint/pci-epf-core.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
index 577a9e490115..defc6aecfdef 100644
--- a/drivers/pci/endpoint/pci-epf-core.c
+++ b/drivers/pci/endpoint/pci-epf-core.c
@@ -338,7 +338,6 @@ static void pci_epf_remove_cfs(struct pci_epf_driver *driver)
 	mutex_lock(&pci_epf_mutex);
 	list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry)
 		pci_ep_cfs_remove_epf_group(group);
-	list_del(&driver->epf_group);
 	mutex_unlock(&pci_epf_mutex);
 }
 
-- 
2.49.0

[PATCH v3 2/2] PCI: endpoint: Fix configfs group removal on driver teardown

[Damien Le Moal]

An endpoint driver configfs attributes group is added to the
epf_group list of struct pci_epf_driver by pci_epf_add_cfs() but an
added group is not removed from this list when the attribute group is
unregistered with pci_ep_cfs_remove_epf_group().

Add the missing list_del() call in pci_ep_cfs_remove_epf_group()
to correctly remove the attribute group from the driver list.

With this change, once the loop over all attribute groups in
pci_epf_remove_cfs() completes, the driver epf_group list should be
empty. Add a WARN_ON() to make sure of that.

Fixes: ef1433f717a2 ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/endpoint/pci-ep-cfs.c   | 1 +
 drivers/pci/endpoint/pci-epf-core.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
index d712c7a866d2..ef50c82e647f 100644
--- a/drivers/pci/endpoint/pci-ep-cfs.c
+++ b/drivers/pci/endpoint/pci-ep-cfs.c
@@ -691,6 +691,7 @@ void pci_ep_cfs_remove_epf_group(struct config_group *group)
 	if (IS_ERR_OR_NULL(group))
 		return;
 
+	list_del(&group->group_entry);
 	configfs_unregister_default_group(group);
 }
 EXPORT_SYMBOL(pci_ep_cfs_remove_epf_group);
diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
index defc6aecfdef..167dc6ee63f7 100644
--- a/drivers/pci/endpoint/pci-epf-core.c
+++ b/drivers/pci/endpoint/pci-epf-core.c
@@ -338,6 +338,7 @@ static void pci_epf_remove_cfs(struct pci_epf_driver *driver)
 	mutex_lock(&pci_epf_mutex);
 	list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry)
 		pci_ep_cfs_remove_epf_group(group);
+	WARN_ON(!list_empty(&driver->epf_group));
 	mutex_unlock(&pci_epf_mutex);
 }
 
-- 
2.49.0

Re: [PATCH v3 0/2] Fix EPF configfs attribute group removal

[Manivannan Sadhasivam]

On Tue, 24 Jun 2025 20:45:42 +0900, Damien Le Moal wrote:
> A couple of patches to fix removal of configfs attribute groups of a PCI
> endpoint function driver.
> 
> Changes from v2:
>  - Use list_del() instead of list_del_init() in patch 2
>  - Added Niklas' review tags
> 
> [...]

Applied, thanks!

[1/2] PCI: endpoint: Fix configfs group list head handling
      commit: d79123d79a8154b4318529b7b2ff7e15806f480b
[2/2] PCI: endpoint: Fix configfs group removal on driver teardown
      commit: 910bdb8197f9322790c738bb32feaa11dba26909

Best regards,
-- 
Manivannan Sadhasivam <mani@kernel.org>