[PATCH net-next] drivers: net: xgene: Fix dma_unmap_single() size

[PATCH net-next] drivers: net: xgene: Fix dma_unmap_single() size

[Thomas Fourier]

In xgene_enet_refill_pagepool(), the skb->data is dma-mapped with length
len which is set to XGENE_ENET_STD_MTU which equals 1536. However, in
xgene_enet_delete_bufpool(), the same buffer is unmapped with length
XGENE_ENET_MAX_MTU which is 9600. This may erroneously unmap other
DMA buffers or cause other issues.

Change unmap length to XGENE_ENET_STD_MTU.

Fixes: 6e434627bce2 ("drivers: net: xgene: fix: Add dma_unmap_single")
Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
---
 drivers/net/ethernet/apm/xgene/xgene_enet_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
index 507db46daf2b..2ddcbf27014e 100644
--- a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
+++ b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
@@ -185,7 +185,7 @@ static void xgene_enet_delete_bufpool(struct xgene_enet_desc_ring *buf_pool)
 
 			raw_desc = &buf_pool->raw_desc16[i];
 			dma_addr = GET_VAL(DATAADDR, le64_to_cpu(raw_desc->m1));
-			dma_unmap_single(dev, dma_addr, XGENE_ENET_MAX_MTU,
+			dma_unmap_single(dev, dma_addr, XGENE_ENET_STD_MTU,
 					 DMA_FROM_DEVICE);
 		}
 	}
-- 
2.53.0

Re: [PATCH net-next] drivers: net: xgene: Fix dma_unmap_single() size

[netdev-bot+sinfo]

Hi!

This is an automated message. This series looks like a fix, but its
commit messages seem to be missing some information:

 - How the issue was discovered, e.g. hit in production, hit during
   development, syzbot report, manual code inspection, LLM or static
   analysis tool scan.

 - Whether the issue was actually triggered, or is only theoretical
   (e.g. found by code inspection). If it was triggered please include
   the symptoms, like the stack trace or error messages.

 - What hardware the change was tested on. For driver fixes please
   mention the device (and if relevant firmware version) used for
   testing, or say that the change was not tested on real hardware.

Please do not repost the series just to address the above. Instead,
reply to this email with the missing information, so that reviewers
can take it into account. If the series needs another revision for
other reasons, please include the information in the commit messages
then.

The evaluation is done by an LLM so it may be wrong, if you think
that is the case please reply and explain.

Re: [PATCH net-next] drivers: net: xgene: Fix dma_unmap_single() size

[Daniel Machon]

Hi Thomas,

> In xgene_enet_refill_pagepool(), the skb->data is dma-mapped with length

To me, it looks like the mapping happens in xgene_enet_refill_bufpool() and not
xgene_enet_refill_pagepool().

> len which is set to XGENE_ENET_STD_MTU which equals 1536. However, in
> xgene_enet_delete_bufpool(), the same buffer is unmapped with length
> XGENE_ENET_MAX_MTU which is 9600. This may erroneously unmap other
> DMA buffers or cause other issues.
> 
> Change unmap length to XGENE_ENET_STD_MTU.
> 
> Fixes: 6e434627bce2 ("drivers: net: xgene: fix: Add dma_unmap_single")

That commit mapped and unmapped with XGENE_ENET_MAX_MTU. At that point, there
was no mismatch. I think the mismatch came with:

Fixes: a9380b0f7be8 ("drivers: net: xgene: Add support for Jumbo frame")

> Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
> ---
>  drivers/net/ethernet/apm/xgene/xgene_enet_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
> index 507db46daf2b..2ddcbf27014e 100644
> --- a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
> +++ b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
> @@ -185,7 +185,7 @@ static void xgene_enet_delete_bufpool(struct xgene_enet_desc_ring *buf_pool)
>  
>  			raw_desc = &buf_pool->raw_desc16[i];
>  			dma_addr = GET_VAL(DATAADDR, le64_to_cpu(raw_desc->m1));
> -			dma_unmap_single(dev, dma_addr, XGENE_ENET_MAX_MTU,
> +			dma_unmap_single(dev, dma_addr, XGENE_ENET_STD_MTU,
>  					 DMA_FROM_DEVICE);
>  		}
>  	}
> -- 
> 2.53.0
> 

/Daniel