devm_ioremap() returns NULL on error. Currently, mlb_usio_probe() does
not check for this case, which results in a NULL pointer dereference.

Add NULL check after devm_ioremap() to prevent this issue.

Fixes: ba44dc043004 ("serial: Add Milbeaut serial control")
Signed-off-by: Henry Martin <bsdhenrymartin@gmail.com>
---
 drivers/tty/serial/milbeaut_usio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/milbeaut_usio.c b/drivers/tty/serial/milbeaut_usio.c
index 059bea18dbab..4e47dca2c4ed 100644
--- a/drivers/tty/serial/milbeaut_usio.c
+++ b/drivers/tty/serial/milbeaut_usio.c
@@ -523,7 +523,10 @@ static int mlb_usio_probe(struct platform_device *pdev)
 	}
 	port->membase = devm_ioremap(&pdev->dev, res->start,
 				resource_size(res));
-
+	if (!port->membase) {
+		ret = -ENOMEM;
+		goto failed;
+	}
 	ret = platform_get_irq_byname(pdev, "rx");
 	mlb_usio_irq[index][RX] = ret;
 
-- 
2.34.1

On Thu, Apr 03, 2025 at 02:28:08PM +0800, Henry Martin wrote:
> devm_ioremap() returns NULL on error. Currently, mlb_usio_probe() does
> not check for this case, which results in a NULL pointer dereference.
> 
> Add NULL check after devm_ioremap() to prevent this issue.
> 
> Fixes: ba44dc043004 ("serial: Add Milbeaut serial control")
> Signed-off-by: Henry Martin <bsdhenrymartin@gmail.com>
> ---
>  drivers/tty/serial/milbeaut_usio.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/milbeaut_usio.c b/drivers/tty/serial/milbeaut_usio.c
> index 059bea18dbab..4e47dca2c4ed 100644
> --- a/drivers/tty/serial/milbeaut_usio.c
> +++ b/drivers/tty/serial/milbeaut_usio.c
> @@ -523,7 +523,10 @@ static int mlb_usio_probe(struct platform_device *pdev)
>  	}
>  	port->membase = devm_ioremap(&pdev->dev, res->start,
>  				resource_size(res));
> -
> +	if (!port->membase) {
> +		ret = -ENOMEM;
> +		goto failed;
> +	}
>  	ret = platform_get_irq_byname(pdev, "rx");
>  	mlb_usio_irq[index][RX] = ret;
>  
> -- 
> 2.34.1
> 
> 

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

devm_ioremap() returns NULL on error. Currently, mlb_usio_probe() does
not check for this case, which results in a NULL pointer dereference.

Add NULL check after devm_ioremap() to prevent this issue.

Cc: stable@vger.kernel.org
Fixes: ba44dc043004 ("serial: Add Milbeaut serial control")
Signed-off-by: Henry Martin <bsdhenrymartin@gmail.com>
---
V1 -> V2: Add cc: stable line.

 drivers/tty/serial/milbeaut_usio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/milbeaut_usio.c b/drivers/tty/serial/milbeaut_usio.c
index 059bea18dbab..4e47dca2c4ed 100644
--- a/drivers/tty/serial/milbeaut_usio.c
+++ b/drivers/tty/serial/milbeaut_usio.c
@@ -523,7 +523,10 @@ static int mlb_usio_probe(struct platform_device *pdev)
 	}
 	port->membase = devm_ioremap(&pdev->dev, res->start,
 				resource_size(res));
-
+	if (!port->membase) {
+		ret = -ENOMEM;
+		goto failed;
+	}
 	ret = platform_get_irq_byname(pdev, "rx");
 	mlb_usio_irq[index][RX] = ret;
 
-- 
2.34.1

…
> Add NULL check after devm_ioremap() to prevent this issue.

Can a summary phrase like “Prevent null pointer dereference in mlb_usio_probe()”
be a bit nicer?

Regards,
Markus

On Thu, Apr 03, 2025 at 10:50:36AM +0200, Markus Elfring wrote:
> …
> > Add NULL check after devm_ioremap() to prevent this issue.
> 
> Can a summary phrase like “Prevent null pointer dereference in mlb_usio_probe()”
> be a bit nicer?
> 
> Regards,
> Markus
> 

Hi,

This is the semi-friendly patch-bot of Greg Kroah-Hartman.

Markus, you seem to have sent a nonsensical or otherwise pointless
review comment to a patch submission on a Linux kernel developer mailing
list.  I strongly suggest that you not do this anymore.  Please do not
bother developers who are actively working to produce patches and
features with comments that, in the end, are a waste of time.

Patch submitter, please ignore Markus's suggestion; you do not need to
follow it at all.  The person/bot/AI that sent it is being ignored by
almost all Linux kernel maintainers for having a persistent pattern of
behavior of producing distracting and pointless commentary, and
inability to adapt to feedback.  Please feel free to also ignore emails
from them.

thanks,

greg k-h's patch email bot