drivers/tty/serial/sccnxp.c:894 sccnxp_probe() error: we previously assumed 'pdata' could be null (see line 887)

Hi Alexander,

FYI, there are new smatch warnings show up in

tree:   git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git tty-next
head:   e27a7d7977b07d701ba247e2ddb95466d95c898f
commit: ec063899b7b308019afa9f5eb32f0a58a6c6ee53 [42/62] serial: sccnxp: Implement polling mode

New smatch warnings:
drivers/tty/serial/sccnxp.c:894 sccnxp_probe() error: we previously assumed 'pdata' could be null (see line 887)

git remote add tty git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
git remote update tty
git checkout ec063899b7b308019afa9f5eb32f0a58a6c6ee53
vim +/pdata +894 drivers/tty/serial/sccnxp.c

1d65c0b1 Alexander Shiyan 2012-08-25  881  	default:
1d65c0b1 Alexander Shiyan 2012-08-25  882  		dev_err(&pdev->dev, "Unsupported chip type %i\n", chiptype);
1d65c0b1 Alexander Shiyan 2012-08-25  883  		ret = -ENOTSUPP;
1d65c0b1 Alexander Shiyan 2012-08-25  884  		goto err_out;
1d65c0b1 Alexander Shiyan 2012-08-25  885  	}
1d65c0b1 Alexander Shiyan 2012-08-25  886  
1d65c0b1 Alexander Shiyan 2012-08-25 @887  	if (!pdata) {
1d65c0b1 Alexander Shiyan 2012-08-25  888  		dev_warn(&pdev->dev,
1d65c0b1 Alexander Shiyan 2012-08-25  889  			 "No platform data supplied, using defaults\n");
1d65c0b1 Alexander Shiyan 2012-08-25  890  		s->pdata.frequency = s->freq_std;
1d65c0b1 Alexander Shiyan 2012-08-25  891  	} else
1d65c0b1 Alexander Shiyan 2012-08-25  892  		memcpy(&s->pdata, pdata, sizeof(struct sccnxp_pdata));
1d65c0b1 Alexander Shiyan 2012-08-25  893  
ec063899 Alexander Shiyan 2012-12-03 @894  	if (pdata->poll_time_us) {
ec063899 Alexander Shiyan 2012-12-03  895  		dev_info(&pdev->dev, "Using poll mode, resolution %u usecs\n",
ec063899 Alexander Shiyan 2012-12-03  896  			 pdata->poll_time_us);
ec063899 Alexander Shiyan 2012-12-03  897  		s->poll = 1;

---
0-DAY kernel build testing backend Open Source Technology Center
http://lists.01.org/mailman/listinfo/kbuild Intel Corporation

I agree. In this case (line 894), there should be:

if (s->pdata.poll_time_us) {
		dev_info(&pdev->dev, "Using poll mode, resolution %u usecs\n",
			 s->pdata.poll_time_us);

...

Today, post the fix. Thank you.

---

This patch fix possible kernel crash if no platform data supplied. We should not use platform data in this case, instead we will use default values from private driver structure.

---
 drivers/tty/serial/sccnxp.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

index 0c86a0b..3fd83e3 100644
@@ -897,9 +897,9 @@ static int sccnxp_probe(struct platform_device *pdev)
 	} else
 		memcpy(&s->pdata, pdata, sizeof(struct sccnxp_pdata));
 
-	if (pdata->poll_time_us) {
+	if (s->pdata.poll_time_us) {
 		dev_info(&pdev->dev, "Using poll mode, resolution %u usecs\n",
-			 pdata->poll_time_us);
+			 s->pdata.poll_time_us);
 		s->poll = 1;
 	}
 

1.7.8.6