On Wed, Jul 26, 2023 at 11:29:42AM -0700, Ira Weiny wrote:
> The following debug object splat was observed in testing.
>
> [ 14.061937] ------------[ cut here ]------------
> [ 14.063899] ODEBUG: free active (active state 0) object: 0000000097d23782 object type: work_struct hint: doe_statemachine_work+0x0/0x510
> [ 14.067480] WARNING: CPU: 1 PID: 71 at lib/debugobjects.c:514 debug_print_object+0x7d/0xb0
> ...
> [ 14.080951] Workqueue: pci 0000:36:00.0 DOE [1 doe_statemachine_work
> [ 14.083485] RIP: 0010:debug_print_object+0x7d/0xb0
> ...
> [ 14.116231] Call Trace:
> [ 14.117652] <TASK>
> [ 14.118958] ? debug_print_object+0x7d/0xb0
> [ 14.120782] ? __warn+0x7d/0x130
> [ 14.122399] ? debug_print_object+0x7d/0xb0
> [ 14.123746] ? report_bug+0x18d/0x1c0
> [ 14.125025] ? handle_bug+0x3c/0x80
> [ 14.126506] ? exc_invalid_op+0x13/0x60
> [ 14.127796] ? asm_exc_invalid_op+0x16/0x20
> [ 14.129380] ? debug_print_object+0x7d/0xb0
> [ 14.130688] ? debug_print_object+0x7d/0xb0
> [ 14.131997] ? __pfx_doe_statemachine_work+0x10/0x10
> [ 14.133597] debug_object_free.part.0+0x11b/0x150
> [ 14.134940] doe_statemachine_work+0x45e/0x510
> [ 14.136348] process_one_work+0x1d4/0x3c0
> ...
> [ 14.161484] </TASK>
> [ 14.162434] ---[ end trace 0000000000000000 ]---
>
> This occurs because destroy_work_on_stack() was called after signaling
> the completion in the calling thread. This creates a race between
> destroy_work_on_stack() and the task->work struct going of scope in the
> pci_doe().
>
> Signal the work complete after destroying the work struct. This is safe
> because signal_task_complete() is the final thing the work item does and
> the workqueue code is careful not to access the work struct after.
>
> Fixes: abf04be0e707 ("PCI/DOE: Fix memory leak with CONFIG_DEBUG_OBJECTS=y")
> Cc: Lukas Wunner <lukas@xxxxxxxxx>
> Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Dan, let me know if you'd rather have me take this.
> ---
> drivers/pci/doe.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
> index 1b97a5ab71a9..e3aab5edaf70 100644
> --- a/drivers/pci/doe.c
> +++ b/drivers/pci/doe.c
> @@ -293,8 +293,8 @@ static int pci_doe_recv_resp(struct pci_doe_mb *doe_mb, struct pci_doe_task *tas
> static void signal_task_complete(struct pci_doe_task *task, int rv)
> {
> task->rv = rv;
> - task->complete(task);
> destroy_work_on_stack(&task->work);
> + task->complete(task);
> }
>
> static void signal_task_abort(struct pci_doe_task *task, int rv)
>
> ---
> base-commit: 20ea1e7d13c1b544fe67c4a8dc3943bb1ab33e6f
> change-id: 20230726-doe-fix-f57943f9ea82
>
> Best regards,
> --
> Ira Weiny <ira.weiny@xxxxxxxxx>
>
