Messages in this thread Patch in this message | | | From | Schspa Shi <> | Subject | [PATCH] PM / devfreq: Strengthen the handling of governor null pointer | Date | Fri, 1 Jul 2022 12:53:15 +0800 |
| |
When new governor start failed & the old governor start failed too, or the governor is removed, the devfreq->governor will be NULL, but we still access it's member from devfreq->governor->name, which will be a crash.
To fix it, change the position of Null pointer judgment before usage.
Another, If the governor is NULL, we try to assign a new governor to it.
Signed-off-by: Schspa Shi <schspa@gmail.com> --- drivers/devfreq/devfreq.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 01474daf4548..30d7f8c128a6 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -1270,7 +1270,13 @@ int devfreq_add_governor(struct devfreq_governor *governor) int ret = 0; struct device *dev = devfreq->dev.parent; - if (!strncmp(devfreq->governor->name, governor->name, + /* + * When new governor start failed & the old governor start + * failed too. devfreq->governor will be NULL. + * Try to assign the new governor to this devfreq device. + */ + if (!devfreq->governor || + !strncmp(devfreq->governor->name, governor->name, DEVFREQ_NAME_LEN)) { /* The following should never occur */ if (devfreq->governor) { @@ -1358,15 +1364,15 @@ int devfreq_remove_governor(struct devfreq_governor *governor) int ret; struct device *dev = devfreq->dev.parent; + /* we should have a devfreq governor! */ + if (!devfreq->governor) { + dev_warn(dev, "%s: Governor %s NOT present\n", + __func__, governor->name); + continue; + } + if (!strncmp(devfreq->governor->name, governor->name, DEVFREQ_NAME_LEN)) { - /* we should have a devfreq governor! */ - if (!devfreq->governor) { - dev_warn(dev, "%s: Governor %s NOT present\n", - __func__, governor->name); - continue; - /* Fall through */ - } ret = devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_STOP, NULL); if (ret) { -- 2.29.0
| |