Message ID | 20210427102427.11066-1-colin.king@canonical.com |
---|---|
State | New |
Headers | show |
Series | [next] gpio: sim: Fix dereference of free'd pointer config | expand |
On Tue, Apr 27, 2021 at 12:24 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. > > Addresses-Coverity: ("Read from pointer aftyer free") > Fixes: a49d14276ac4 ("gpio: sim: allocate IDA numbers earlier") > Signed-off-by: Colin Ian King <colin.king@canonical.com> > --- > drivers/gpio/gpio-sim.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c > index 2e2e6399e453..7bba5783a043 100644 > --- a/drivers/gpio/gpio-sim.c > +++ b/drivers/gpio/gpio-sim.c > @@ -751,8 +751,10 @@ gpio_sim_config_make_item(struct config_group *group, const char *name) > > config->id = ida_alloc(&gpio_sim_ida, GFP_KERNEL); > if (config->id < 0) { > + int id = config->id; > + > kfree(config); > - return ERR_PTR(config->id); > + return ERR_PTR(id); > } > > config_item_init_type_name(&config->item, name, > -- > 2.30.2 > Thanks! Can you do something like this: 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; I think this looks more elegant without the local variable inside the if. Bart
On 27/04/2021 12:33, Bartosz Golaszewski wrote: > On Tue, Apr 27, 2021 at 12:24 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. >> >> Addresses-Coverity: ("Read from pointer aftyer free") >> Fixes: a49d14276ac4 ("gpio: sim: allocate IDA numbers earlier") >> Signed-off-by: Colin Ian King <colin.king@canonical.com> >> --- >> drivers/gpio/gpio-sim.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c >> index 2e2e6399e453..7bba5783a043 100644 >> --- a/drivers/gpio/gpio-sim.c >> +++ b/drivers/gpio/gpio-sim.c >> @@ -751,8 +751,10 @@ gpio_sim_config_make_item(struct config_group *group, const char *name) >> >> config->id = ida_alloc(&gpio_sim_ida, GFP_KERNEL); >> if (config->id < 0) { >> + int id = config->id; >> + >> kfree(config); >> - return ERR_PTR(config->id); >> + return ERR_PTR(id); >> } >> >> config_item_init_type_name(&config->item, name, >> -- >> 2.30.2 >> > > Thanks! Can you do something like this: > > 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; > > > I think this looks more elegant without the local variable inside the if. OK, good idea, V2 sent. > > Bart >
diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c index 2e2e6399e453..7bba5783a043 100644 --- a/drivers/gpio/gpio-sim.c +++ b/drivers/gpio/gpio-sim.c @@ -751,8 +751,10 @@ gpio_sim_config_make_item(struct config_group *group, const char *name) config->id = ida_alloc(&gpio_sim_ida, GFP_KERNEL); if (config->id < 0) { + int id = config->id; + kfree(config); - return ERR_PTR(config->id); + return ERR_PTR(id); } config_item_init_type_name(&config->item, name,