Re: [PATCH] ACPI: APEI: check return value of task_work_add to prevent memory leaks

[Hanjun Guo]

Hi Wupeng,

On 2026/4/17 14:50, Wupeng Ma wrote:
> task_work_add() can fail with -ESRCH if the target task is exiting.
> When it fails, the caller must handle the error and free any allocated
> resources.
>
> ghes_do_memory_failure() allocates a twcb structure from ghes_estatus_pool
> before calling task_work_add(). If task_work_add() fails, twcb is leaked.
>
> This can happen due to a race during task exit:
>
>    do_exit()
>      exit_mm()           # current->mm cleared
>      exit_task_work()    # task->task_works = &work_exited
>
> ghes_do_memory_failure() checks current->mm before allocating twcb,
> but exit_task_work() may run before task_work_add() completes.  At that
> point task->task_works == &work_exited, causing task_work_add() to fail.

There are multi places in the kernel to call task_work_add() without
checking the return value, does this race only cause bug in
ghes_do_memory_failure()?

Thanks
Hanjun