linux-kernel - Re: [PATCH] powerpc: floppy: Add missing checks after DMA map

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Message-ID: <16e789a6-87f4-4f7a-9f13-edf47f9f401f@csgroup.eu>
Date: Fri, 20 Jun 2025 09:44:55 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Thomas Fourier <fourier.thomas@...il.com>
Cc: Madhavan Srinivasan <maddy@...ux.ibm.com>,
 Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
 linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc: floppy: Add missing checks after DMA map

Hi Thomas,

Le 19/06/2025 à 13:07, Thomas Fourier a écrit :
> [Vous ne recevez pas souvent de courriers de fourier.thomas@...il.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
> 
> The DMA map functions can fail and should be tested for errors.
> 
> Signed-off-by: Thomas Fourier <fourier.thomas@...il.com>
> ---
>   arch/powerpc/include/asm/floppy.h | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/include/asm/floppy.h b/arch/powerpc/include/asm/floppy.h
> index f8ce178b43b7..df8ce2ae636d 100644
> --- a/arch/powerpc/include/asm/floppy.h
> +++ b/arch/powerpc/include/asm/floppy.h
> @@ -144,9 +144,14 @@ static int hard_dma_setup(char *addr, unsigned long size, int mode, int io)
>                  bus_addr = 0;
>          }
> 
> -       if (!bus_addr)  /* need to map it */
> +       if (!bus_addr) {        /* need to map it */
>                  bus_addr = dma_map_single(&isa_bridge_pcidev->dev, addr, size,
>                                            dir);
> +               if (dma_mapping_error(&isa_bridge_pcidev->dev, bus_addr)) {
> +                       bus_addr = 0;

bus_addr is a local variable, there is no point in setting it to zero 
here. Just return -ENOMEM.

> +                       return -ENOMEM;
> +               }
> +       }
> 
>          /* remember this one as prev */
>          prev_addr = addr;
> --
> 2.43.0
>