In __iodyn_find_io_region(), pcmcia_make_resource() is assigned to
res and used in pci_bus_alloc_resource(). There is a dereference of res
in pci_bus_alloc_resource(), which could lead to a NULL pointer
dereference on failure of pcmcia_make_resource().

Fix this bug by adding a check of res.

Found by code review, complie tested only.

Cc: stable@vger.kernel.org
Fixes: 49b1153adfe1 ("pcmcia: move all pcmcia_resource_ops providers into one module")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
---
 drivers/pcmcia/rsrc_iodyn.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pcmcia/rsrc_iodyn.c b/drivers/pcmcia/rsrc_iodyn.c
index b04b16496b0c..2677b577c1f8 100644
--- a/drivers/pcmcia/rsrc_iodyn.c
+++ b/drivers/pcmcia/rsrc_iodyn.c
@@ -62,6 +62,9 @@ static struct resource *__iodyn_find_io_region(struct pcmcia_socket *s,
 	unsigned long min = base;
 	int ret;
 
+	if (!res)
+		return NULL;
+
 	data.mask = align - 1;
 	data.offset = base & data.mask;
 
-- 
2.25.1

Many thanks, applied to pcmcia-next. This allocation is practically no-fail
owing to GFP_KERNEL and the small allocation size, and rsrc_iodyn.c is on
its way out, but it's better safe than to be sorry.

Best,
	Dominik

Am Tue, Aug 12, 2025 at 03:25:09PM +0800 schrieb Ma Ke:
> In __iodyn_find_io_region(), pcmcia_make_resource() is assigned to
> res and used in pci_bus_alloc_resource(). There is a dereference of res
> in pci_bus_alloc_resource(), which could lead to a NULL pointer
> dereference on failure of pcmcia_make_resource().
> 
> Fix this bug by adding a check of res.
> 
> Found by code review, complie tested only.
> 
> Cc: stable@vger.kernel.org
> Fixes: 49b1153adfe1 ("pcmcia: move all pcmcia_resource_ops providers into one module")
> Signed-off-by: Ma Ke <make24@iscas.ac.cn>
> ---
>  drivers/pcmcia/rsrc_iodyn.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/pcmcia/rsrc_iodyn.c b/drivers/pcmcia/rsrc_iodyn.c
> index b04b16496b0c..2677b577c1f8 100644
> --- a/drivers/pcmcia/rsrc_iodyn.c
> +++ b/drivers/pcmcia/rsrc_iodyn.c
> @@ -62,6 +62,9 @@ static struct resource *__iodyn_find_io_region(struct pcmcia_socket *s,
>  	unsigned long min = base;
>  	int ret;
>  
> +	if (!res)
> +		return NULL;
> +
>  	data.mask = align - 1;
>  	data.offset = base & data.mask;
>  
> -- 
> 2.25.1
> 
>