2021-09-02 00:05:09

by Imran Khan

Subject: [RFC PATCH v2 1/2] lib, stackdepot: check stackdepot handle before accessing slabs.

stack_depot_save allocates slabs that will be used for storing
objects in future.If this slab allocation fails we may get to
a situation where space allocation for a new stack_record fails,
causing stack_depot_save to return 0 as handle.
If user of this handle ends up invoking stack_depot_fetch with
this handle value, current implementation of stack_depot_fetch
will end up using slab from wrong index.
To avoid this check handle value at the beginning.

Signed-off-by: Imran Khan <[email protected]>
Suggested-by: Vlastimil Babka <[email protected]>
---
lib/stackdepot.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 0a2e417f83cb..67439c082490 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -232,6 +232,9 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
struct stack_record *stack;

*entries = NULL;
+ if (!handle)
+ return 0;
+
if (parts.slabindex > depot_index) {
WARN(1, "slab index %d out of bounds (%d) for stack id %08x\n",
parts.slabindex, depot_index, handle);
--
2.30.2

2021-09-02 07:59:15

by Vlastimil Babka

Subject: Re: [RFC PATCH v2 1/2] lib, stackdepot: check stackdepot handle before accessing slabs.

On 9/2/21 02:01, Imran Khan wrote:
> stack_depot_save allocates slabs that will be used for storing
> objects in future.If this slab allocation fails we may get to
> a situation where space allocation for a new stack_record fails,
> causing stack_depot_save to return 0 as handle.
> If user of this handle ends up invoking stack_depot_fetch with
> this handle value, current implementation of stack_depot_fetch
> will end up using slab from wrong index.
> To avoid this check handle value at the beginning.
>
> Signed-off-by: Imran Khan <[email protected]>
> Suggested-by: Vlastimil Babka <[email protected]>

Acked-by: Vlastimil Babka <[email protected]>

> ---
> lib/stackdepot.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/lib/stackdepot.c b/lib/stackdepot.c
> index 0a2e417f83cb..67439c082490 100644
> --- a/lib/stackdepot.c
> +++ b/lib/stackdepot.c
> @@ -232,6 +232,9 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
> struct stack_record *stack;
>
> *entries = NULL;
> + if (!handle)
> + return 0;
> +
> if (parts.slabindex > depot_index) {
> WARN(1, "slab index %d out of bounds (%d) for stack id %08x\n",
> parts.slabindex, depot_index, handle);
>