linux-kernel - Re: [PATCH 3/9] dmaengine: idxd: Fix possible invalid memory access after FLR

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Message-ID: <87349sgzcy.fsf@AUSNATLYNCH.amd.com>
Date: Fri, 15 Aug 2025 14:26:53 -0500
From: Nathan Lynch <nathan.lynch@....com>
To: Vinicius Costa Gomes <vinicius.gomes@...el.com>, Dave Jiang
	<dave.jiang@...el.com>, Vinod Koul <vkoul@...nel.org>, Fenghua Yu
	<fenghua.yu@...el.com>, Dan Williams <dan.j.williams@...el.com>
CC: <dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/9] dmaengine: idxd: Fix possible invalid memory access
 after FLR

Vinicius Costa Gomes <vinicius.gomes@...el.com> writes:

> In the case that the first Field Level Reset (FLR) concludes

I think you mean Function Level Reset? (here and in other changes in the
series)


> correctly, but in the second FLR the scratch area for the saved
> configuration cannot be allocated, it's possible for a invalid memory
> access to happen.
>
> Always set the deallocated scratch area to NULL after FLR completes.
>
> Fixes: 98d187a98903 ("dmaengine: idxd: Enable Function Level Reset (FLR) for halt")
> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>
> ---
>  drivers/dma/idxd/init.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index a58b8cdbfa60ba9f00b91a737df01517885bc41a..31e00af136a7e13887d3ffd00efbb05864712a80 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -1136,6 +1136,7 @@ static void idxd_reset_done(struct pci_dev *pdev)
>  	}
>  out:
>  	kfree(idxd->idxd_saved);
> +	idxd->idxd_saved = NULL;
>  }
>  
>  static const struct pci_error_handlers idxd_error_handler = {
>
> -- 
> 2.50.1