Andrew Morton[off-list ref] wrote:

On Wed, 21 Aug 2024 14:21:32 +0800 Ma Ke [off-list ref] wrote:

quoted

pinmux_generic_get_function() can return NULL and the pointer 'function'
was dereferenced without checking against NULL. Add checking of pointer
'function' in pcs_get_function().

Found by code review.

...

--- a/drivers/pinctrl/pinctrl-single.c
+++ b/drivers/pinctrl/pinctrl-single.c

@@ -345,6 +345,8 @@ static int pcs_get_function(struct pinctrl_dev *pctldev, unsigned pin,
 		return -ENOTSUPP;
 	fselector = setting->func;
 	function = pinmux_generic_get_function(pctldev, fselector);
+	if (!function)
+		return -EINVAL;
 	*func = function->data;
 	if (!(*func)) {
 		dev_err(pcs->dev, "%s could not find function%i\n",

Maybe.  Or maybe pinmux_generic_get_function() must always return a
valid pointer, in which case

	BUG_ON(!function);

is an appropriate thing.  But a null-pointer deref gives us the same
info, so no change is needed.

btw, pinmux_generic_get_function() is funny:

	if (!function)
		return NULL;

	return function;

Thank you for your response to the vulnerability I submitted. Yes, we 
believe there is a similar issue. As described in [1], 
pinmux_generic_get_function() could return as NULL and lead to a d
ereferencing problem, and a similar issue exists in this code. It is better
to add checking of pointer 'function' in pcs_get_function(). The discovery 
of this problem was confirmed through manual review of the code and 
compilation testing.

[1] https://lore.kernel.org/linux-arm-kernel/CACRpkdYwBNjGzODYqvz+oScsO3u=R0dXMkP4UfqmosDugPFWRA@mail.gmail.com/T/ (local)

--
Regards,

Ma Ke