On Thu, Mar 12, 2020 at 12:30 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> We should check for a NULL pointer first before adding the offset.
> Otherwise if the pointer is NULL and the offset is non-zero, it will
> lead to an Oops.
Thanks!
> Fixes: d45048e65a59 ("lib/stackdepot.c: check depot_index before accessing the stack slab")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Acked-by: Alexander Potapenko <glider@xxxxxxxxxx>
> ---
> lib/stackdepot.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/lib/stackdepot.c b/lib/stackdepot.c
> index da5d1880bf34..2caffc64e4c8 100644
> --- a/lib/stackdepot.c
> +++ b/lib/stackdepot.c
> @@ -207,18 +207,16 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
> size_t offset = parts.offset << STACK_ALLOC_ALIGN;
> struct stack_record *stack;
>
> + *entries = NULL;
> if (parts.slabindex > depot_index) {
> WARN(1, "slab index %d out of bounds (%d) for stack id %08x\n",
> parts.slabindex, depot_index, handle);
> - *entries = NULL;
> return 0;
> }
> slab = stack_slabs[parts.slabindex];
> - stack = slab + offset;
> - if (!stack) {
> - *entries = NULL;
> + if (!slab)
> return 0;
> - }
> + stack = slab + offset;
>
> *entries = stack->entries;
> return stack->size;
> --
> 2.20.1
>
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
