[PATCH net v1 1/1] net: usb: lan78xx: Sanitize return values of register read/write functions

[PATCH net v1 1/1] net: usb: lan78xx: Sanitize return values of register read/write functions

[Oleksij Rempel]

usb_control_msg() returns the number of transferred bytes or a negative
error code. The current implementation propagates the transferred byte
count, which is unintended. This affects code paths that assume a
boolean success/failure check, such as the EEPROM detection logic.

Fix this by ensuring lan78xx_read_reg() and lan78xx_write_reg() return
only 0 on success and preserve negative error codes.

This approach is consistent with existing usage, as the transferred byte
count is not explicitly checked elsewhere.

Fixes: 8b1b2ca83b20 ("net: usb: lan78xx: Improve error handling in EEPROM and OTP operations")
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/all/ac965de8-f320-430f-80f6-b16f4e1ba06d@sirena.org.uk
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 drivers/net/usb/lan78xx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index a91bf9c7e31d..137adf6d5b08 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -627,7 +627,7 @@ static int lan78xx_read_reg(struct lan78xx_net *dev, u32 index, u32 *data)
 
 	kfree(buf);
 
-	return ret;
+	return ret < 0 ? ret : 0;
 }
 
 static int lan78xx_write_reg(struct lan78xx_net *dev, u32 index, u32 data)
@@ -658,7 +658,7 @@ static int lan78xx_write_reg(struct lan78xx_net *dev, u32 index, u32 data)
 
 	kfree(buf);
 
-	return ret;
+	return ret < 0 ? ret : 0;
 }
 
 static int lan78xx_update_reg(struct lan78xx_net *dev, u32 reg, u32 mask,
-- 
2.39.5

RE: [PATCH net v1 1/1] net: usb: lan78xx: Sanitize return values of register read/write functions

[Woojung.Huh]

Add proper maintainers in the list
Thangaraj Samynathan <Thangaraj.S@microchip.com>
Rengarajan Sundararajan <Rengarajan.S@microchip.com>

https://web.git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/tree/MAINTAINERS#n24528

> -----Original Message-----
> From: Oleksij Rempel <o.rempel@pengutronix.de>
> Sent: Friday, March 7, 2025 5:12 AM
> To: David S. Miller <davem@davemloft.net>; Eric Dumazet
> <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni
> <pabeni@redhat.com>; Woojung Huh - C21699 <Woojung.Huh@microchip.com>;
> Andrew Lunn <andrew+netdev@lunn.ch>
> Cc: Oleksij Rempel <o.rempel@pengutronix.de>; Mark Brown
> <broonie@kernel.org>; kernel@pengutronix.de; linux-kernel@vger.kernel.org;
> netdev@vger.kernel.org; UNGLinuxDriver <UNGLinuxDriver@microchip.com>; Phil
> Elwell <phil@raspberrypi.org>
> Subject: [PATCH net v1 1/1] net: usb: lan78xx: Sanitize return values of
> register read/write functions
> 
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the
> content is safe
> 
> usb_control_msg() returns the number of transferred bytes or a negative
> error code. The current implementation propagates the transferred byte
> count, which is unintended. This affects code paths that assume a
> boolean success/failure check, such as the EEPROM detection logic.
> 
> Fix this by ensuring lan78xx_read_reg() and lan78xx_write_reg() return
> only 0 on success and preserve negative error codes.
> 
> This approach is consistent with existing usage, as the transferred byte
> count is not explicitly checked elsewhere.
> 
> Fixes: 8b1b2ca83b20 ("net: usb: lan78xx: Improve error handling in EEPROM
> and OTP operations")
> Reported-by: Mark Brown <broonie@kernel.org>
> Closes: https://lore.kernel.org/all/ac965de8-f320-430f-80f6-
> b16f4e1ba06d@sirena.org.uk
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---
>  drivers/net/usb/lan78xx.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
> index a91bf9c7e31d..137adf6d5b08 100644
> --- a/drivers/net/usb/lan78xx.c
> +++ b/drivers/net/usb/lan78xx.c
> @@ -627,7 +627,7 @@ static int lan78xx_read_reg(struct lan78xx_net *dev, u32
> index, u32 *data)
> 
>         kfree(buf);
> 
> -       return ret;
> +       return ret < 0 ? ret : 0;
>  }
> 
>  static int lan78xx_write_reg(struct lan78xx_net *dev, u32 index, u32 data)
> @@ -658,7 +658,7 @@ static int lan78xx_write_reg(struct lan78xx_net *dev,
> u32 index, u32 data)
> 
>         kfree(buf);
> 
> -       return ret;
> +       return ret < 0 ? ret : 0;
>  }
> 
>  static int lan78xx_update_reg(struct lan78xx_net *dev, u32 reg, u32 mask,
> --
> 2.39.5

Re: [PATCH net v1 1/1] net: usb: lan78xx: Sanitize return values of register read/write functions

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 616 bytes --]

On Fri, Mar 07, 2025 at 11:12:23AM +0100, Oleksij Rempel wrote:
> usb_control_msg() returns the number of transferred bytes or a negative
> error code. The current implementation propagates the transferred byte
> count, which is unintended. This affects code paths that assume a
> boolean success/failure check, such as the EEPROM detection logic.
> 
> Fix this by ensuring lan78xx_read_reg() and lan78xx_write_reg() return
> only 0 on success and preserve negative error codes.

Tested-by: Mark Brown <broonie@kernel.org>

This fixes NFS boot on the Raspberry Pi 3+, it'd be good to get it into
v6.14.

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Re: [PATCH net v1 1/1] net: usb: lan78xx: Sanitize return values of register read/write functions

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Fri,  7 Mar 2025 11:12:23 +0100 you wrote:
> usb_control_msg() returns the number of transferred bytes or a negative
> error code. The current implementation propagates the transferred byte
> count, which is unintended. This affects code paths that assume a
> boolean success/failure check, such as the EEPROM detection logic.
> 
> Fix this by ensuring lan78xx_read_reg() and lan78xx_write_reg() return
> only 0 on success and preserve negative error codes.
> 
> [...]

Here is the summary with links:
  - [net,v1,1/1] net: usb: lan78xx: Sanitize return values of register read/write functions
    https://git.kernel.org/netdev/net/c/cfa693bf9d53

You are awesome, thank you!
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