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Message-ID: <ZUzcTBmSPxIs5iH3@nanopsycho>
Date: Thu, 9 Nov 2023 14:19:08 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: "Kubalewski, Arkadiusz" <arkadiusz.kubalewski@...el.com>
Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"vadim.fedorenko@...ux.dev" <vadim.fedorenko@...ux.dev>,
"Michalik, Michal" <michal.michalik@...el.com>,
"Olech, Milena" <milena.olech@...el.com>,
"pabeni@...hat.com" <pabeni@...hat.com>,
"kuba@...nel.org" <kuba@...nel.org>
Subject: Re: [PATCH net 2/3] dpll: fix pin dump crash for rebound module
Thu, Nov 09, 2023 at 01:20:48PM CET, arkadiusz.kubalewski@...el.com wrote:
>>From: Jiri Pirko <jiri@...nulli.us>
>>Sent: Wednesday, November 8, 2023 3:30 PM
>>
>>Wed, Nov 08, 2023 at 11:32:25AM CET, arkadiusz.kubalewski@...el.com 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
>>>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")
>>>Signed-off-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>
>>>---
>>> drivers/dpll/dpll_core.c | 4 ++--
>>> drivers/dpll/dpll_core.h | 4 ++--
>>> drivers/dpll/dpll_netlink.c | 28 ++++++++++++++--------------
>>> 3 files changed, 18 insertions(+), 18 deletions(-)
>>>
>>>diff --git a/drivers/dpll/dpll_core.c b/drivers/dpll/dpll_core.c
>>>index 3568149b9562..4077b562ba3b 100644
>>>--- a/drivers/dpll/dpll_core.c
>>>+++ b/drivers/dpll/dpll_core.c
>>>@@ -442,7 +442,7 @@ dpll_pin_alloc(u64 clock_id, u32 pin_idx, struct
>>>module *module,
>>> ret = -EINVAL;
>>> goto err;
>>> }
>>>- pin->prop = prop;
>>>+ memcpy(&pin->prop, prop, sizeof(pin->prop));
>>
>>Odd, you don't care about the pointer within this structure?
>>
>
>Well, true. Need a fix.
>Wondering if copying idea is better than just assigning prop pointer on
>each call to dpll_pin_get(..) function (when pin already exists)?
Not sure what do you mean. Examples please.
>
>Thank you!
>Arkadiusz
>
>>
>>> refcount_set(&pin->refcount, 1);
>>> xa_init_flags(&pin->dpll_refs, XA_FLAGS_ALLOC);
>>> xa_init_flags(&pin->parent_refs, XA_FLAGS_ALLOC);
>>>@@ -634,7 +634,7 @@ 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 93fc6c4b8a78..963bbbbe6660 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;
>>> }
>>>@@ -403,7 +403,7 @@ 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;
>>>
>>>@@ -696,7 +696,7 @@ 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;
>>> }
>>>@@ -732,7 +732,7 @@ 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;
>>> }
>>>@@ -759,7 +759,7 @@ 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;
>>> }
>>>@@ -787,7 +787,7 @@ 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;
>>> }
>>>@@ -817,8 +817,8 @@ 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;
>>>@@ -999,7 +999,7 @@ 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
>>>
>
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