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SubjectRe: [PATCH][next][V2] gpio: sim: Fix dereference of free'd pointer config
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On 27/04/2021 13:11, Andy Shevchenko wrote:
> On Tue, Apr 27, 2021 at 2:49 PM Colin King <colin.king@canonical.com> wrote:
>>
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> 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 <andy.shevchenko@gmail.com>
>
>> 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 <colin.king@canonical.com>
>> ---
>> 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
>>
>
>

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