[PATCH v2 net] net: usb: sr9700: fix uninitialized variable use in sr_mdio_read

[PATCH v2 net] net: usb: sr9700: fix uninitialized variable use in sr_mdio_read

[Ma Ke]

It could lead to error happen because the variable res is not updated if
the call to sr_share_read_word returns an error. In this particular case
error code was returned and res stayed uninitialized.

This can be avoided by checking the return value of sr_share_read_word
and propagating the error if the read operation failed.

Found by code review.

Fixes: c9b37458e956 ("USB2NET : SR9700 : One chip USB 1.1 USB2NET SR9700Device Driver Support")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
---
Changes in v2:
- modified the subject as suggestions.
---
 drivers/net/usb/sr9700.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/usb/sr9700.c b/drivers/net/usb/sr9700.c
index 0a662e42ed96..d5bc596f4521 100644
--- a/drivers/net/usb/sr9700.c
+++ b/drivers/net/usb/sr9700.c
@@ -179,6 +179,7 @@ static int sr_mdio_read(struct net_device *netdev, int phy_id, int loc)
 	struct usbnet *dev = netdev_priv(netdev);
 	__le16 res;
 	int rc = 0;
+	int err;
 
 	if (phy_id) {
 		netdev_dbg(netdev, "Only internal phy supported\n");
@@ -193,7 +194,10 @@ static int sr_mdio_read(struct net_device *netdev, int phy_id, int loc)
 		if (value & NSR_LINKST)
 			rc = 1;
 	}
-	sr_share_read_word(dev, 1, loc, &res);
+	err = sr_share_read_word(dev, 1, loc, &res);
+	if (err < 0)
+		return err;
+
 	if (rc == 1)
 		res = le16_to_cpu(res) | BMSR_LSTATUS;
 	else
-- 
2.25.1

Re: [PATCH v2 net] net: usb: sr9700: fix uninitialized variable use in sr_mdio_read

[Greg KH]

On Wed, Jul 24, 2024 at 09:15:54AM +0800, Ma Ke wrote:
> It could lead to error happen because the variable res is not updated if
> the call to sr_share_read_word returns an error. In this particular case
> error code was returned and res stayed uninitialized.
> 
> This can be avoided by checking the return value of sr_share_read_word
> and propagating the error if the read operation failed.
> 
> Found by code review.
> 
> Fixes: c9b37458e956 ("USB2NET : SR9700 : One chip USB 1.1 USB2NET SR9700Device Driver Support")
> Signed-off-by: Ma Ke <make24@iscas.ac.cn>
> ---
> Changes in v2:
> - modified the subject as suggestions.
> ---
>  drivers/net/usb/sr9700.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- You have marked a patch with a "Fixes:" tag for a commit that is in an
  older released kernel, yet you do not have a cc: stable line in the
  signed-off-by area at all, which means that the patch will not be
  applied to any older kernel releases.  To properly fix this, please
  follow the documented rules in the
  Documentation/process/stable-kernel-rules.rst file for how to resolve
  this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot

Re: [PATCH v2 net] net: usb: sr9700: fix uninitialized variable use in sr_mdio_read

[Andrew Lunn]

On Wed, Jul 24, 2024 at 09:15:54AM +0800, Ma Ke wrote:
> It could lead to error happen because the variable res is not updated if
> the call to sr_share_read_word returns an error. In this particular case
> error code was returned and res stayed uninitialized.
> 
> This can be avoided by checking the return value of sr_share_read_word
> and propagating the error if the read operation failed.
> 
> Found by code review.

For V1, you were given the comment that there are other functions
which also suffer from this problem. You don't appear to of addressed
them in this patch, nor replied saying you won't because....

Please don't ignore reviewers.

	Andrew