2021-04-27 11:50:59

by Colin King

Subject: [PATCH][next][V2] gpio: sim: Fix dereference of free'd pointer config

From: Colin Ian King <[email protected]>

The error return of config->id dereferences the kfree'd object config.
Fix this by using a temporary variable for the id to avoid this issue.

Addresses-Coverity: ("Read from pointer aftyer free")
Fixes: a49d14276ac4 ("gpio: sim: allocate IDA numbers earlier")
Signed-off-by: Colin Ian King <[email protected]>
---
V2: Don't make id local to the if statement to improve coding style.
Thanks to Bartosz Golaszewski for this improvement suggestion.
---
drivers/gpio/gpio-sim.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
index 2e2e6399e453..b21541c0b700 100644
--- a/drivers/gpio/gpio-sim.c
+++ b/drivers/gpio/gpio-sim.c
@@ -744,20 +744,22 @@ static struct config_item *
gpio_sim_config_make_item(struct config_group *group, const char *name)
{
struct gpio_sim_chip_config *config;
+ int id;

config = kzalloc(sizeof(*config), GFP_KERNEL);
if (!config)
return ERR_PTR(-ENOMEM);

- config->id = ida_alloc(&gpio_sim_ida, GFP_KERNEL);
- if (config->id < 0) {
+ id = ida_alloc(&gpio_sim_ida, GFP_KERNEL);
+ if (id < 0) {
kfree(config);
- return ERR_PTR(config->id);
+ return ERR_PTR(id);
}

config_item_init_type_name(&config->item, name,
&gpio_sim_chip_config_type);
config->num_lines = 1;
+ config->id = id;
mutex_init(&config->lock);

return &config->item;
--
2.30.2

2021-04-27 12:12:59

by Andy Shevchenko

Subject: Re: [PATCH][next][V2] gpio: sim: Fix dereference of free'd pointer config

On Tue, Apr 27, 2021 at 2:49 PM Colin King <[email protected]> wrote:
>
> From: Colin Ian King <[email protected]>
>
> The error return of config->id dereferences the kfree'd object config.
> Fix this by using a temporary variable for the id to avoid this issue.

Thanks!
I'm wondering how I missed this... Nevertheless

Reviewed-by: Andy Shevchenko <[email protected]>

> Addresses-Coverity: ("Read from pointer aftyer free")

after

> Fixes: a49d14276ac4 ("gpio: sim: allocate IDA numbers earlier")
> Signed-off-by: Colin Ian King <[email protected]>
> ---
> V2: Don't make id local to the if statement to improve coding style.
> Thanks to Bartosz Golaszewski for this improvement suggestion.
> ---
> drivers/gpio/gpio-sim.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
> index 2e2e6399e453..b21541c0b700 100644
> --- a/drivers/gpio/gpio-sim.c
> +++ b/drivers/gpio/gpio-sim.c
> @@ -744,20 +744,22 @@ static struct config_item *
> gpio_sim_config_make_item(struct config_group *group, const char *name)
> {
> struct gpio_sim_chip_config *config;
> + int id;
>
> config = kzalloc(sizeof(*config), GFP_KERNEL);
> if (!config)
> return ERR_PTR(-ENOMEM);
>
> - config->id = ida_alloc(&gpio_sim_ida, GFP_KERNEL);
> - if (config->id < 0) {
> + id = ida_alloc(&gpio_sim_ida, GFP_KERNEL);
> + if (id < 0) {
> kfree(config);
> - return ERR_PTR(config->id);
> + return ERR_PTR(id);
> }
>
> config_item_init_type_name(&config->item, name,
> &gpio_sim_chip_config_type);
> config->num_lines = 1;
> + config->id = id;
> mutex_init(&config->lock);
>
> return &config->item;
> --
> 2.30.2
>


--
With Best Regards,
Andy Shevchenko

2021-04-27 12:21:54

by Colin King

Subject: Re: [PATCH][next][V2] gpio: sim: Fix dereference of free'd pointer config

On 27/04/2021 13:11, Andy Shevchenko wrote:
> On Tue, Apr 27, 2021 at 2:49 PM Colin King <[email protected]> wrote:
>>
>> From: Colin Ian King <[email protected]>
>>
>> The error return of config->id dereferences the kfree'd object config.
>> Fix this by using a temporary variable for the id to avoid this issue.
>
> Thanks!
> I'm wondering how I missed this... Nevertheless
>
> Reviewed-by: Andy Shevchenko <[email protected]>
>
>> Addresses-Coverity: ("Read from pointer aftyer free")
>
> after
>

Can that be fixed before applying rather me sending a V3?

>> Fixes: a49d14276ac4 ("gpio: sim: allocate IDA numbers earlier")
>> Signed-off-by: Colin Ian King <[email protected]>
>> ---
>> V2: Don't make id local to the if statement to improve coding style.
>> Thanks to Bartosz Golaszewski for this improvement suggestion.
>> ---
>> drivers/gpio/gpio-sim.c | 8 +++++---
>> 1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
>> index 2e2e6399e453..b21541c0b700 100644
>> --- a/drivers/gpio/gpio-sim.c
>> +++ b/drivers/gpio/gpio-sim.c
>> @@ -744,20 +744,22 @@ static struct config_item *
>> gpio_sim_config_make_item(struct config_group *group, const char *name)
>> {
>> struct gpio_sim_chip_config *config;
>> + int id;
>>
>> config = kzalloc(sizeof(*config), GFP_KERNEL);
>> if (!config)
>> return ERR_PTR(-ENOMEM);
>>
>> - config->id = ida_alloc(&gpio_sim_ida, GFP_KERNEL);
>> - if (config->id < 0) {
>> + id = ida_alloc(&gpio_sim_ida, GFP_KERNEL);
>> + if (id < 0) {
>> kfree(config);
>> - return ERR_PTR(config->id);
>> + return ERR_PTR(id);
>> }
>>
>> config_item_init_type_name(&config->item, name,
>> &gpio_sim_chip_config_type);
>> config->num_lines = 1;
>> + config->id = id;
>> mutex_init(&config->lock);
>>
>> return &config->item;
>> --
>> 2.30.2
>>
>
>

2021-04-27 12:59:33

by Bartosz Golaszewski

Subject: Re: [PATCH][next][V2] gpio: sim: Fix dereference of free'd pointer config

On Tue, Apr 27, 2021 at 2:20 PM Colin Ian King <[email protected]> wrote:
>
> On 27/04/2021 13:11, Andy Shevchenko wrote:
> > On Tue, Apr 27, 2021 at 2:49 PM Colin King <[email protected]> wrote:
> >>
> >> From: Colin Ian King <[email protected]>
> >>
> >> The error return of config->id dereferences the kfree'd object config.
> >> Fix this by using a temporary variable for the id to avoid this issue.
> >
> > Thanks!
> > I'm wondering how I missed this... Nevertheless
> >
> > Reviewed-by: Andy Shevchenko <[email protected]>
> >
> >> Addresses-Coverity: ("Read from pointer aftyer free")
> >
> > after
> >
>
> Can that be fixed before applying rather me sending a V3?
>

No need, I'll add it and apply right away.

Bartosz

> >> Fixes: a49d14276ac4 ("gpio: sim: allocate IDA numbers earlier")
> >> Signed-off-by: Colin Ian King <[email protected]>
> >> ---
> >> V2: Don't make id local to the if statement to improve coding style.
> >> Thanks to Bartosz Golaszewski for this improvement suggestion.
> >> ---
> >> drivers/gpio/gpio-sim.c | 8 +++++---
> >> 1 file changed, 5 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
> >> index 2e2e6399e453..b21541c0b700 100644
> >> --- a/drivers/gpio/gpio-sim.c
> >> +++ b/drivers/gpio/gpio-sim.c
> >> @@ -744,20 +744,22 @@ static struct config_item *
> >> gpio_sim_config_make_item(struct config_group *group, const char *name)
> >> {
> >> struct gpio_sim_chip_config *config;
> >> + int id;
> >>
> >> config = kzalloc(sizeof(*config), GFP_KERNEL);
> >> if (!config)
> >> return ERR_PTR(-ENOMEM);
> >>
> >> - config->id = ida_alloc(&gpio_sim_ida, GFP_KERNEL);
> >> - if (config->id < 0) {
> >> + id = ida_alloc(&gpio_sim_ida, GFP_KERNEL);
> >> + if (id < 0) {
> >> kfree(config);
> >> - return ERR_PTR(config->id);
> >> + return ERR_PTR(id);
> >> }
> >>
> >> config_item_init_type_name(&config->item, name,
> >> &gpio_sim_chip_config_type);
> >> config->num_lines = 1;
> >> + config->id = id;
> >> mutex_init(&config->lock);
> >>
> >> return &config->item;
> >> --
> >> 2.30.2
> >>
> >
> >
>