| Message ID | 20180823185140.GA29028@embeddedor.com |
|---|---|
| State | Accepted |
| Headers | show |
| Series | rtc: sun6i: Use struct_size() in kzalloc() | expand |
On Thu, Aug 23, 2018 at 11:51 AM, Gustavo A. R. Silva <gustavo@embeddedor.com> wrote: > One of the more common cases of allocation size calculations is finding > the size of a structure that has a zero-sized array at the end, along > with memory for some number of elements for that array. For example: > > struct foo { > int stuff; > void *entry[]; > }; > > instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL); > > Instead of leaving these open-coded and prone to type mistakes, we can > now use the new struct_size() helper: > > instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL); > > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> > --- > drivers/rtc/rtc-sun6i.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c > index 2cd5a7b..fe07310 100644 > --- a/drivers/rtc/rtc-sun6i.c > +++ b/drivers/rtc/rtc-sun6i.c > @@ -199,8 +199,7 @@ static void __init sun6i_rtc_clk_init(struct device_node *node) > if (!rtc) > return; > > - clk_data = kzalloc(sizeof(*clk_data) + (sizeof(*clk_data->hws) * 2), > - GFP_KERNEL); > + clk_data = kzalloc(struct_size(clk_data, hws, 2), GFP_KERNEL); > if (!clk_data) { > kfree(rtc); > return; This looks like entirely correct to me, but I'm surprised the Coccinelle script didn't discover this. I guess the isomorphisms don't cover the parenthesis? -Kees
On Thu, Aug 23, 2018 at 11:51 AM, Gustavo A. R. Silva <gustavo@embeddedor.com> wrote: > One of the more common cases of allocation size calculations is finding > the size of a structure that has a zero-sized array at the end, along > with memory for some number of elements for that array. For example: > > struct foo { > int stuff; > void *entry[]; > }; > > instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL); > > Instead of leaving these open-coded and prone to type mistakes, we can > now use the new struct_size() helper: > > instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL); > > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> > --- > drivers/rtc/rtc-sun6i.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c > index 2cd5a7b..fe07310 100644 > --- a/drivers/rtc/rtc-sun6i.c > +++ b/drivers/rtc/rtc-sun6i.c > @@ -199,8 +199,7 @@ static void __init sun6i_rtc_clk_init(struct device_node *node) > if (!rtc) > return; > > - clk_data = kzalloc(sizeof(*clk_data) + (sizeof(*clk_data->hws) * 2), > - GFP_KERNEL); > + clk_data = kzalloc(struct_size(clk_data, hws, 2), GFP_KERNEL); > if (!clk_data) { > kfree(rtc); > return; Reviewed-by: Kees Cook <keescook@chromium.org> -Kees
On 8/23/18 3:56 PM, Kees Cook wrote: >> >> - clk_data = kzalloc(sizeof(*clk_data) + (sizeof(*clk_data->hws) * 2), >> - GFP_KERNEL); >> + clk_data = kzalloc(struct_size(clk_data, hws, 2), GFP_KERNEL); >> if (!clk_data) { >> kfree(rtc); >> return; > > This looks like entirely correct to me, but I'm surprised the > Coccinelle script didn't discover this. I guess the isomorphisms don't > cover the parenthesis? > Apparently. If I manually remove the ()s, the cocci script successfully generates a patch. -- Gustavo
On 23/08/2018 13:51:40-0500, Gustavo A. R. Silva wrote: > One of the more common cases of allocation size calculations is finding > the size of a structure that has a zero-sized array at the end, along > with memory for some number of elements for that array. For example: > > struct foo { > int stuff; > void *entry[]; > }; > > instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL); > > Instead of leaving these open-coded and prone to type mistakes, we can > now use the new struct_size() helper: > > instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL); > > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> > --- > drivers/rtc/rtc-sun6i.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > Applied, thanks.
diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c index 2cd5a7b..fe07310 100644 --- a/drivers/rtc/rtc-sun6i.c +++ b/drivers/rtc/rtc-sun6i.c @@ -199,8 +199,7 @@ static void __init sun6i_rtc_clk_init(struct device_node *node) if (!rtc) return; - clk_data = kzalloc(sizeof(*clk_data) + (sizeof(*clk_data->hws) * 2), - GFP_KERNEL); + clk_data = kzalloc(struct_size(clk_data, hws, 2), GFP_KERNEL); if (!clk_data) { kfree(rtc); return;
One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example: struct foo { int stuff; void *entry[]; }; instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL); Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper: instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL); Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> --- drivers/rtc/rtc-sun6i.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)