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SubjectRe: [PATCH][next][V2] gpio: sim: Fix dereference of free'd pointer config
On Tue, Apr 27, 2021 at 2:20 PM Colin Ian King <colin.king@canonical.com> wrote:
>
> 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?
>

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 <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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