In ravb_start_xmit(), ravb driver uses u32 variable to store result of
dma_map_single() call. Since ravb hardware has 32-bit address fields in
descriptors, this works properly when mapping is successful - it is
platform's job to provide mapping addresses that fit into hardware
limitations.

However, in failure case dma_map_single() returns DMA_MAPPING_ERROR
constant that is 64-bit when dma_addr_t is 64-bit. Storing this constant
in u32 leads to truncation, and further call to dma_mapping_error()
fails to notice the error.

Fix that by storing result of dma_map_single() in a dma_addr_t
variable.

Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
---
 drivers/net/ethernet/renesas/ravb_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 8649b3e90edb..0e3731f50fc2 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -1949,7 +1949,7 @@ static netdev_tx_t ravb_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 	struct ravb_tstamp_skb *ts_skb;
 	struct ravb_tx_desc *desc;
 	unsigned long flags;
-	u32 dma_addr;
+	dma_addr_t dma_addr;
 	void *buffer;
 	u32 entry;
 	u32 len;
-- 
2.39.2

On 1/12/2024 8:22 PM, Nikita Yushchenko wrote:
> In ravb_start_xmit(), ravb driver uses u32 variable to store result of
> dma_map_single() call. Since ravb hardware has 32-bit address fields in
> descriptors, this works properly when mapping is successful - it is
> platform's job to provide mapping addresses that fit into hardware
> limitations.
> 
> However, in failure case dma_map_single() returns DMA_MAPPING_ERROR
> constant that is 64-bit when dma_addr_t is 64-bit. Storing this constant
> in u32 leads to truncation, and further call to dma_mapping_error()
> fails to notice the error.
> 
> Fix that by storing result of dma_map_single() in a dma_addr_t
> variable.
> 
> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>

Nit: since this is a bug fix you should prefix your patches with "[PATCH 
net]", see:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/maintainer-netdev.rst#n62
-- 
Florian

On 1/13/24 7:22 AM, Nikita Yushchenko wrote:

> In ravb_start_xmit(), ravb driver uses u32 variable to store result of
> dma_map_single() call. Since ravb hardware has 32-bit address fields in
> descriptors, this works properly when mapping is successful - it is
> platform's job to provide mapping addresses that fit into hardware
> limitations.
> 
> However, in failure case dma_map_single() returns DMA_MAPPING_ERROR
> constant that is 64-bit when dma_addr_t is 64-bit. Storing this constant
> in u32 leads to truncation, and further call to dma_mapping_error()
> fails to notice the error.
> 
> Fix that by storing result of dma_map_single() in a dma_addr_t
> variable.
> 
> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>

Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>

[...]

MBR, Sergey

Hello Nikita,

Thanks for your patch.

On 2024-01-13 10:22:21 +0600, Nikita Yushchenko wrote:
> In ravb_start_xmit(), ravb driver uses u32 variable to store result of
> dma_map_single() call. Since ravb hardware has 32-bit address fields in
> descriptors, this works properly when mapping is successful - it is
> platform's job to provide mapping addresses that fit into hardware
> limitations.
> 
> However, in failure case dma_map_single() returns DMA_MAPPING_ERROR
> constant that is 64-bit when dma_addr_t is 64-bit. Storing this constant
> in u32 leads to truncation, and further call to dma_mapping_error()
> fails to notice the error.
> 
> Fix that by storing result of dma_map_single() in a dma_addr_t
> variable.
> 
> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> ---
>  drivers/net/ethernet/renesas/ravb_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index 8649b3e90edb..0e3731f50fc2 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -1949,7 +1949,7 @@ static netdev_tx_t ravb_start_xmit(struct sk_buff *skb, struct net_device *ndev)
>  	struct ravb_tstamp_skb *ts_skb;
>  	struct ravb_tx_desc *desc;
>  	unsigned long flags;
> -	u32 dma_addr;
> +	dma_addr_t dma_addr;
>  	void *buffer;
>  	u32 entry;
>  	u32 len;
> -- 
> 2.39.2
> 
> 

-- 
Kind Regards,
Niklas Söderlund