On Mon, Dec 25, 2006 at 06:35:57PM +0900, Akinobu Mita wrote:
> On Mon, Dec 25, 2006 at 10:55:51AM +0200, Muli Ben-Yehuda wrote:
> > This is correct because cct is allocated via alloc_percpu, which in
> > turn calls kzalloc, which means cct->task is NULL by default, but it's
> > a little too obscure for me. How about making it explicit?
> >
> > task = kthread_create(...)
> > if (!IS_ERR(task))
> > cct->task = task;
> > else
> > cct->task = NULL;
> >
> > return cct->task;
>
> Subject: [PATCH -mm] ehca: avoid crash on kthread_create() failure (v3)
>
> This patch disallows invalid task_struct pointer returned by
> kthread_create() to be written to percpu data to avoid crash.
>
> Cc: Heiko Carstens <[EMAIL PROTECTED]>
> Cc: Hoang-Nam Nguyen <[EMAIL PROTECTED]>
> Cc: Christoph Raisch <[EMAIL PROTECTED]>
> Signed-off-by: Akinobu Mita <[EMAIL PROTECTED]>
>
> ---
> drivers/infiniband/hw/ehca/ehca_irq.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> Index: 2.6-mm/drivers/infiniband/hw/ehca/ehca_irq.c
> ===================================================================
> --- 2.6-mm.orig/drivers/infiniband/hw/ehca/ehca_irq.c
> +++ 2.6-mm/drivers/infiniband/hw/ehca/ehca_irq.c
> @@ -606,15 +606,20 @@ static int comp_task(void *__cct)
> static struct task_struct *create_comp_task(struct ehca_comp_pool *pool,
> int cpu)
> {
> + struct task_struct *task;
> struct ehca_cpu_comp_task *cct;
>
> cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
> spin_lock_init(&cct->task_lock);
> INIT_LIST_HEAD(&cct->cq_list);
> init_waitqueue_head(&cct->wait_queue);
> - cct->task = kthread_create(comp_task, cct, "ehca_comp/%d", cpu);
> + task = kthread_create(comp_task, cct, "ehca_comp/%d", cpu);
> + if (!IS_ERR(task))
> + cct->task = task;
> + else
> + cct->task = NULL;
>
> - return cct->task;
> + return task;
This should be return cct->task, since we later test the return value
of create_comp_task against NULL, e.g., in comp_poll_callback and
ehca_create_comp_pool.
Cheers,
Muli
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