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dmaengine: idxd: Avoid unnecessary destruction of file_ida

Message ID 20240130013954.2024231-1-fenghua.yu@intel.com (mailing list archive)
State Changes Requested
Headers show
Series dmaengine: idxd: Avoid unnecessary destruction of file_ida | expand

Commit Message

Fenghua Yu Jan. 30, 2024, 1:39 a.m. UTC
file_ida is allocated during cdev open and is freed accordingly
during cdev release. This sequence is guaranteed by driver file
operations. Therefore, there is no need to destroy an already empty
file_ida when the WQ cdev is removed.

Worse, ida_free() in cdev release may happen after destruction of 
file_ida per WQ cdev. This can lead to accessing an id in file_ida
after it has been destroyed, resulting in a kernel panic.

Remove ida_destroy(&file_ida) to address these issues.

Fixes: e6fd6d7e5f0f ("dmaengine: idxd: add a device to represent the file opened")
Signed-off-by: Lijun Pan <lijun.pan@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
---
 drivers/dma/idxd/cdev.c | 1 -
 1 file changed, 1 deletion(-)

Comments

Dave Jiang Jan. 30, 2024, 3:34 p.m. UTC | #1
On 1/29/24 18:39, Fenghua Yu wrote:
> file_ida is allocated during cdev open and is freed accordingly
> during cdev release. This sequence is guaranteed by driver file
> operations. Therefore, there is no need to destroy an already empty
> file_ida when the WQ cdev is removed.
> 
> Worse, ida_free() in cdev release may happen after destruction of 
> file_ida per WQ cdev. This can lead to accessing an id in file_ida
> after it has been destroyed, resulting in a kernel panic.
> 
> Remove ida_destroy(&file_ida) to address these issues.
> 
> Fixes: e6fd6d7e5f0f ("dmaengine: idxd: add a device to represent the file opened")
> Signed-off-by: Lijun Pan <lijun.pan@intel.com>
> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  drivers/dma/idxd/cdev.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
> index baa51927675c..3311c920f47a 100644
> --- a/drivers/dma/idxd/cdev.c
> +++ b/drivers/dma/idxd/cdev.c
> @@ -1272,7 +1272,6 @@ void idxd_wq_del_cdev(struct idxd_wq *wq)
>  	struct idxd_cdev *idxd_cdev;
>  
>  	idxd_cdev = wq->idxd_cdev;
> -	ida_destroy(&file_ida);
>  	wq->idxd_cdev = NULL;
>  	cdev_device_del(&idxd_cdev->cdev, cdev_dev(idxd_cdev));
>  	put_device(cdev_dev(idxd_cdev));
diff mbox series

Patch

diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
index baa51927675c..3311c920f47a 100644
--- a/drivers/dma/idxd/cdev.c
+++ b/drivers/dma/idxd/cdev.c
@@ -1272,7 +1272,6 @@  void idxd_wq_del_cdev(struct idxd_wq *wq)
 	struct idxd_cdev *idxd_cdev;
 
 	idxd_cdev = wq->idxd_cdev;
-	ida_destroy(&file_ida);
 	wq->idxd_cdev = NULL;
 	cdev_device_del(&idxd_cdev->cdev, cdev_dev(idxd_cdev));
 	put_device(cdev_dev(idxd_cdev));