Le 25/05/2023 à 05:22, Wells Lu 呂芳騰 a écrit :
Le 23/05/2023 à 21:37, andy.shevchenko@xxxxxxxxx a écrit :
Tue, May 23, 2023 at 05:39:51PM +0000, Wells Lu 呂芳騰 kirjoitti:
Fix Smatch static checker warning:
potential null dereference 'configs'. (kmalloc returns null)
...
configs = kmalloc(sizeof(*configs), GFP_KERNEL);
+ if (!configs)
+ return -ENOMEM;
"Fixing" by adding a memory leak is not probably a good approach.
Do you mean I need to free all memory which are allocated in this
subroutine before return -ENOMEM?
This is my understanding of the code. But as I said... (see below)
...
configs = kmalloc(sizeof(*configs), GFP_KERNEL);
+ if (!configs)
+ return -ENOMEM;
Ditto.
...
It might be that I'm mistaken. In this case please add an
explanation why in the commit message.
^^^
Hmmm, not so sure.
Should be looked at more carefully, but
dt_to_map_one_config (in /drivers/pinctrl/devicetree.c)
.dt_node_to_map
--> sppctl_dt_node_to_map
Should dt_to_map_one_config() fail, pinctrl_dt_free_maps() is called (see
https://elixir.bootlin.com/linux/v6.4-rc1/source/drivers/pinctrl/devicetree.c#L281)
pinctrl_dt_free_maps() calls dt_free_map(), which calls .dt_free_map, so
pinctrl_utils_free_map()
(see
https://elixir.bootlin.com/linux/v6.4-rc1/source/drivers/pinctrl/sunplus/sppctl.c#L97
8)
Finally the needed kfree seem to be called from here.
(see
https://elixir.bootlin.com/linux/v6.4-rc1/source/drivers/pinctrl/pinctrl-utils.c#L119
)
*This should obviously be double checked*, but looks safe to me.
BUT, in the same function, the of_get_parent() should be undone in case
of error, as done at the end of the function, in the normal path.
This one seems to be missing, should a memory allocation error occur.
Just my 2c,
CJ
Thank you for your comments.
From the report of kmemleak, returning -ENOMEM directly causes memory leak. We
need to free any memory allocated in this subroutine before returning -ENOMEM.
I'll send a new patch that will free the allocated memory and call of_node_put()
when an error happens.
Hi,
(adding Dan in copy because the initial report is related to smatch)
I don't use kmemleak, but could you share some input about its report?
I've not rechecked my analysis, but it looked promising.
Maybe Dan could also give a look at it and confirm your finding, or dig
further with smatch to make sure that its static analysis was complete
enough.
CJ
Best regards,
Wells Lu
