2006-08-16 22:24:05

by Josh Triplett

Subject: [PATCH] rcu: Avoid kthread_stop on invalid pointer if rcutorture reader startup fails

rcu_torture_init kmallocs the array of reader threads, then creates each one
with kthread_run, cleaning up with rcu_torture_cleanup if this fails.
rcu_torture_cleanup calls kthread_stop on any non-NULL pointer in the array;
however, any readers after the one that failed to start up will have invalid
pointers, not null pointers. Avoid this by using kzalloc instead.

Signed-off-by: Josh Triplett <[email protected]>
---
kernel/rcutorture.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index aff0064..8b09c95 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -779,7 +779,7 @@ rcu_torture_init(void)
writer_task = NULL;
goto unwind;
}
- reader_tasks = kmalloc(nrealreaders * sizeof(reader_tasks[0]),
+ reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
GFP_KERNEL);
if (reader_tasks == NULL) {
VERBOSE_PRINTK_ERRSTRING("out of memory");
--
1.4.1.1

2006-08-16 23:37:10

by Paul E. McKenney

Subject: Re: [PATCH] rcu: Avoid kthread_stop on invalid pointer if rcutorture reader startup fails

On Wed, Aug 16, 2006 at 03:24:02PM -0700, Josh Triplett wrote:
> rcu_torture_init kmallocs the array of reader threads, then creates each one
> with kthread_run, cleaning up with rcu_torture_cleanup if this fails.
> rcu_torture_cleanup calls kthread_stop on any non-NULL pointer in the array;
> however, any readers after the one that failed to start up will have invalid
> pointers, not null pointers. Avoid this by using kzalloc instead.

Good catch!!!

Acked-by: Paul E. McKenney <[email protected]>
> Signed-off-by: Josh Triplett <[email protected]>
> ---
> kernel/rcutorture.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
> index aff0064..8b09c95 100644
> --- a/kernel/rcutorture.c
> +++ b/kernel/rcutorture.c
> @@ -779,7 +779,7 @@ rcu_torture_init(void)
> writer_task = NULL;
> goto unwind;
> }
> - reader_tasks = kmalloc(nrealreaders * sizeof(reader_tasks[0]),
> + reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
> GFP_KERNEL);
> if (reader_tasks == NULL) {
> VERBOSE_PRINTK_ERRSTRING("out of memory");
> --
> 1.4.1.1
>
>