Subject: Re: [PATCH net v2 2/4] dpll: fix pin dump crash for rebound module

From: Jiri Pirko <[email-masked]>
Date: Thu, 4 Jan 2024 16:40:54 +0100

Thu, Jan 04, 2024 at 12:11:30PM CET, [email-masked] wrote:
>When a kernel module is unbound but the pin resources were not entirely
>freed (other kernel module instance have had kept the reference to that

Wait, you talk about module, yet you mean pci instance of the same
module, don't you?

>pin), and kernel module is again bound, the pin properties would not be
>updated (the properties are only assigned when memory for the pin is
>allocated), prop pointer still points to the kernel module memory of
>the kernel module which was deallocated on the unbind.
>
>If the pin dump is invoked in this state, the result is a kernel crash.
>Prevent the crash by storing persistent pin properties in dpll subsystem,
>copy the content from the kernel module when pin is allocated, instead of
>using memory of the kernel module.
>
>Fixes: 9431063ad323 ("dpll: core: Add DPLL framework base functions")
>Fixes: 9d71b54b65b1 ("dpll: netlink: Add DPLL framework base functions")
>Reviewed-by: Jan Glaza <[email-masked]>
>Reviewed-by: Przemek Kitszel <[email-masked]>
>Signed-off-by: Arkadiusz Kubalewski <[email-masked]>
>---
> drivers/dpll/dpll_core.c    | 29 ++++++++++++++++++++++++++---
> drivers/dpll/dpll_core.h    |  4 ++--
> drivers/dpll/dpll_netlink.c | 28 ++++++++++++++--------------
> 3 files changed, 42 insertions(+), 19 deletions(-)
>
>diff --git a/drivers/dpll/dpll_core.c b/drivers/dpll/dpll_core.c
>index 3568149b9562..0b469096ef79 100644
>--- a/drivers/dpll/dpll_core.c
>+++ b/drivers/dpll/dpll_core.c
>@@ -429,6 +429,7 @@ dpll_pin_alloc(u64 clock_id, u32 pin_idx, struct module *module,
> 	       const struct dpll_pin_properties *prop)
> {
> 	struct dpll_pin *pin;
>+	size_t freq_size;
> 	int ret;
> 
> 	pin = kzalloc(sizeof(*pin), GFP_KERNEL);
>@@ -440,9 +441,22 @@ dpll_pin_alloc(u64 clock_id, u32 pin_idx, struct module *module,
> 	if (WARN_ON(prop->type < DPLL_PIN_TYPE_MUX ||
> 		    prop->type > DPLL_PIN_TYPE_MAX)) {
> 		ret = -EINVAL;
>-		goto err;
>+		goto pin_free;
> 	}
>-	pin->prop = prop;
>+	memcpy(&pin->prop, prop, sizeof(pin->prop));
>+	if (prop->freq_supported && prop->freq_supported_num) {
>+		freq_size = prop->freq_supported_num *
>+			    sizeof(*pin->prop.freq_supported);
>+		pin->prop.freq_supported = kmemdup(prop->freq_supported,
>+						   freq_size, GFP_KERNEL);
>+		if (!pin->prop.freq_supported) {
>+			ret = -ENOMEM;
>+			goto pin_free;
>+		}
>+	}
>+	pin->prop.board_label = kstrdup(prop->board_label, GFP_KERNEL);
>+	pin->prop.panel_label = kstrdup(prop->panel_label, GFP_KERNEL);
>+	pin->prop.package_label = kstrdup(prop->package_label, GFP_KERNEL);

Care to check the return values? Also don't kstrdup null pointers, does
not make much sense.

Could you perhaps move the prop dup/free to separate functions?

> 	refcount_set(&pin->refcount, 1);
> 	xa_init_flags(&pin->dpll_refs, XA_FLAGS_ALLOC);
> 	xa_init_flags(&pin->parent_refs, XA_FLAGS_ALLOC);
>@@ -451,8 +465,13 @@ dpll_pin_alloc(u64 clock_id, u32 pin_idx, struct module *module,
> 		goto err;
> 	return pin;
> err:
>+	kfree(pin->prop.package_label);
>+	kfree(pin->prop.panel_label);
>+	kfree(pin->prop.board_label);
>+	kfree(pin->prop.freq_supported);
> 	xa_destroy(&pin->dpll_refs);
> 	xa_destroy(&pin->parent_refs);
>+pin_free:
> 	kfree(pin);
> 	return ERR_PTR(ret);
> }
>@@ -512,6 +531,10 @@ void dpll_pin_put(struct dpll_pin *pin)
> 		xa_destroy(&pin->dpll_refs);
> 		xa_destroy(&pin->parent_refs);
> 		xa_erase(&dpll_pin_xa, pin->id);
>+		kfree(pin->prop.board_label);
>+		kfree(pin->prop.panel_label);
>+		kfree(pin->prop.package_label);
>+		kfree(pin->prop.freq_supported);
> 		kfree(pin);
> 	}
> 	mutex_unlock(&dpll_lock);
>@@ -634,7 +657,7 @@ int dpll_pin_on_pin_register(struct dpll_pin *parent, struct dpll_pin *pin,
> 	unsigned long i, stop;
> 	int ret;
> 
>-	if (WARN_ON(parent->prop->type != DPLL_PIN_TYPE_MUX))
>+	if (WARN_ON(parent->prop.type != DPLL_PIN_TYPE_MUX))
> 		return -EINVAL;
> 
> 	if (WARN_ON(!ops) ||
>diff --git a/drivers/dpll/dpll_core.h b/drivers/dpll/dpll_core.h
>index 5585873c5c1b..717f715015c7 100644
>--- a/drivers/dpll/dpll_core.h
>+++ b/drivers/dpll/dpll_core.h
>@@ -44,7 +44,7 @@ struct dpll_device {
>  * @module:		module of creator
>  * @dpll_refs:		hold referencees to dplls pin was registered with
>  * @parent_refs:	hold references to parent pins pin was registered with
>- * @prop:		pointer to pin properties given by registerer
>+ * @prop:		pin properties copied from the registerer
>  * @rclk_dev_name:	holds name of device when pin can recover clock from it
>  * @refcount:		refcount
>  **/
>@@ -55,7 +55,7 @@ struct dpll_pin {
> 	struct module *module;
> 	struct xarray dpll_refs;
> 	struct xarray parent_refs;
>-	const struct dpll_pin_properties *prop;
>+	struct dpll_pin_properties prop;
> 	refcount_t refcount;
> };
> 
>diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c
>index b53478374a38..3ce9995013f1 100644
>--- a/drivers/dpll/dpll_netlink.c
>+++ b/drivers/dpll/dpll_netlink.c
>@@ -278,17 +278,17 @@ dpll_msg_add_pin_freq(struct sk_buff *msg, struct dpll_pin *pin,
> 	if (nla_put_64bit(msg, DPLL_A_PIN_FREQUENCY, sizeof(freq), &freq,
> 			  DPLL_A_PIN_PAD))
> 		return -EMSGSIZE;
>-	for (fs = 0; fs < pin->prop->freq_supported_num; fs++) {
>+	for (fs = 0; fs < pin->prop.freq_supported_num; fs++) {
> 		nest = nla_nest_start(msg, DPLL_A_PIN_FREQUENCY_SUPPORTED);
> 		if (!nest)
> 			return -EMSGSIZE;
>-		freq = pin->prop->freq_supported[fs].min;
>+		freq = pin->prop.freq_supported[fs].min;
> 		if (nla_put_64bit(msg, DPLL_A_PIN_FREQUENCY_MIN, sizeof(freq),
> 				  &freq, DPLL_A_PIN_PAD)) {
> 			nla_nest_cancel(msg, nest);
> 			return -EMSGSIZE;
> 		}
>-		freq = pin->prop->freq_supported[fs].max;
>+		freq = pin->prop.freq_supported[fs].max;
> 		if (nla_put_64bit(msg, DPLL_A_PIN_FREQUENCY_MAX, sizeof(freq),
> 				  &freq, DPLL_A_PIN_PAD)) {
> 			nla_nest_cancel(msg, nest);
>@@ -304,9 +304,9 @@ static bool dpll_pin_is_freq_supported(struct dpll_pin *pin, u32 freq)
> {
> 	int fs;
> 
>-	for (fs = 0; fs < pin->prop->freq_supported_num; fs++)
>-		if (freq >= pin->prop->freq_supported[fs].min &&
>-		    freq <= pin->prop->freq_supported[fs].max)
>+	for (fs = 0; fs < pin->prop.freq_supported_num; fs++)
>+		if (freq >= pin->prop.freq_supported[fs].min &&
>+		    freq <= pin->prop.freq_supported[fs].max)
> 			return true;
> 	return false;
> }
>@@ -398,7 +398,7 @@ static int
> dpll_cmd_pin_get_one(struct sk_buff *msg, struct dpll_pin *pin,
> 		     struct netlink_ext_ack *extack)
> {
>-	const struct dpll_pin_properties *prop = pin->prop;
>+	const struct dpll_pin_properties *prop = &pin->prop;
> 	struct dpll_pin_ref *ref;
> 	int ret;
> 
>@@ -691,7 +691,7 @@ dpll_pin_on_pin_state_set(struct dpll_pin *pin, u32 parent_idx,
> 	int ret;
> 
> 	if (!(DPLL_PIN_CAPABILITIES_STATE_CAN_CHANGE &
>-	      pin->prop->capabilities)) {
>+	      pin->prop.capabilities)) {
> 		NL_SET_ERR_MSG(extack, "state changing is not allowed");
> 		return -EOPNOTSUPP;
> 	}
>@@ -727,7 +727,7 @@ dpll_pin_state_set(struct dpll_device *dpll, struct dpll_pin *pin,
> 	int ret;
> 
> 	if (!(DPLL_PIN_CAPABILITIES_STATE_CAN_CHANGE &
>-	      pin->prop->capabilities)) {
>+	      pin->prop.capabilities)) {
> 		NL_SET_ERR_MSG(extack, "state changing is not allowed");
> 		return -EOPNOTSUPP;
> 	}
>@@ -754,7 +754,7 @@ dpll_pin_prio_set(struct dpll_device *dpll, struct dpll_pin *pin,
> 	int ret;
> 
> 	if (!(DPLL_PIN_CAPABILITIES_PRIORITY_CAN_CHANGE &
>-	      pin->prop->capabilities)) {
>+	      pin->prop.capabilities)) {
> 		NL_SET_ERR_MSG(extack, "prio changing is not allowed");
> 		return -EOPNOTSUPP;
> 	}
>@@ -782,7 +782,7 @@ dpll_pin_direction_set(struct dpll_pin *pin, struct dpll_device *dpll,
> 	int ret;
> 
> 	if (!(DPLL_PIN_CAPABILITIES_DIRECTION_CAN_CHANGE &
>-	      pin->prop->capabilities)) {
>+	      pin->prop.capabilities)) {
> 		NL_SET_ERR_MSG(extack, "direction changing is not allowed");
> 		return -EOPNOTSUPP;
> 	}
>@@ -812,8 +812,8 @@ dpll_pin_phase_adj_set(struct dpll_pin *pin, struct nlattr *phase_adj_attr,
> 	int ret;
> 
> 	phase_adj = nla_get_s32(phase_adj_attr);
>-	if (phase_adj > pin->prop->phase_range.max ||
>-	    phase_adj < pin->prop->phase_range.min) {
>+	if (phase_adj > pin->prop.phase_range.max ||
>+	    phase_adj < pin->prop.phase_range.min) {
> 		NL_SET_ERR_MSG_ATTR(extack, phase_adj_attr,
> 				    "phase adjust value not supported");
> 		return -EINVAL;
>@@ -997,7 +997,7 @@ dpll_pin_find(u64 clock_id, struct nlattr *mod_name_attr,
> 	unsigned long i;
> 
> 	xa_for_each_marked(&dpll_pin_xa, i, pin, DPLL_REGISTERED) {
>-		prop = pin->prop;
>+		prop = &pin->prop;
> 		cid_match = clock_id ? pin->clock_id == clock_id : true;
> 		mod_match = mod_name_attr && module_name(pin->module) ?
> 			!nla_strcmp(mod_name_attr,
>-- 
>2.38.1
>