On Fri, Feb 23, 2024 at 3:20 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> The stack_pools[] array has DEPOT_MAX_POOLS. The "pools_num" tracks the
> number of pools which are initialized. See depot_init_pool() for more
> details.
>
> If pool_index == pools_num_cached, this will read one element beyond what
> we want. If not all the pools are initialized, then the pool will be
> NULL, triggering a WARN(), and if they are all initialized it will read
> one element beyond the end of the array.
>
> Fixes: b29d31885814 ("lib/stackdepot: store free stack records in a freelist")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
> From static analysis. What seems to have happened is that originally
> we stored the highest index instead of the number of elements and when
> we changed the > to >= comparison was overlooked.
>
> lib/stackdepot.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/stackdepot.c b/lib/stackdepot.c
> index 8c795bb20afb..af6cc19a2003 100644
> --- a/lib/stackdepot.c
> +++ b/lib/stackdepot.c
> @@ -447,7 +447,7 @@ static struct stack_record *depot_fetch_stack(depot_stack_handle_t handle)
>
> lockdep_assert_not_held(&pool_lock);
>
> - if (pool_index > pools_num_cached) {
> + if (pool_index >= pools_num_cached) {
> WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n",
> pool_index, pools_num_cached, handle);
> return NULL;
> --
> 2.43.0
>
Hi Dan,
This patch needs to be rebased onto "lib/stackdepot: Fix first entry
having a 0-handle", which is now in mm-stable.
Thank you!
