linux-kernel - Re: memory leak and other oddness in pinctrl-mvebu.c

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Date:	Sat, 09 Mar 2013 23:39:31 +0000
From:	David Woodhouse <dwmw2@...radead.org>
To:	Jason Cooper <jason@...edaemon.net>
Cc:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Stephen Warren <swarren@...dotorg.org>,
	linux-kernel@...r.kernel.org
Subject: Re: memory leak and other oddness in pinctrl-mvebu.c

On Sat, 2013-03-09 at 17:53 -0500, Jason Cooper wrote:
> > +     if (!nr_funcs)
> 
> shouldn't this be:
> 
>         if (nr_funcs <= 0)

Hm, no. But the loop should terminate if nr_funcs ever reaches zero,
otherwise funcs->num_groups will be off the end of the original array:

diff --git a/drivers/pinctrl/mvebu/pinctrl-mvebu.c b/drivers/pinctrl/mvebu/pinctrl-mvebu.c
index c689c04..8bbc607 100644
--- a/drivers/pinctrl/mvebu/pinctrl-mvebu.c
+++ b/drivers/pinctrl/mvebu/pinctrl-mvebu.c
@@ -478,16 +478,21 @@ static struct pinctrl_ops mvebu_pinctrl_ops = {
 	.dt_free_map = mvebu_pinctrl_dt_free_map,
 };
 
-static int _add_function(struct mvebu_pinctrl_function *funcs, const char *name)
+static int _add_function(struct mvebu_pinctrl_function *funcs, int nr_funcs,
+			 const char *name)
 {
-	while (funcs->num_groups) {
+	while (nr_funcs && funcs->num_groups) {
 		/* function already there */
 		if (strcmp(funcs->name, name) == 0) {
 			funcs->num_groups++;
 			return -EEXIST;
 		}
 		funcs++;
+		nr_funcs--;
 	}
+	if (!nr_funcs)
+		return -EOVERFLOW;
+
 	funcs->name = name;
 	funcs->num_groups = 1;
 	return 0;
@@ -501,7 +506,7 @@ static int mvebu_pinctrl_build_functions(struct platform_device *pdev,
 	int n, s;
 
 	/* we allocate functions for number of pins and hope
-	 * there are less unique functions than pins available */
+	 * there are fewer unique functions than pins available */
 	funcs = devm_kzalloc(&pdev->dev, pctl->desc.npins *
 			     sizeof(struct mvebu_pinctrl_function), GFP_KERNEL);
 	if (!funcs)
@@ -510,26 +515,27 @@ static int mvebu_pinctrl_build_functions(struct platform_device *pdev,
 	for (n = 0; n < pctl->num_groups; n++) {
 		struct mvebu_pinctrl_group *grp = &pctl->groups[n];
 		for (s = 0; s < grp->num_settings; s++) {
+			int ret;
+
 			/* skip unsupported settings on this variant */
 			if (pctl->variant &&
 			    !(pctl->variant & grp->settings[s].variant))
 				continue;
 
 			/* check for unique functions and count groups */
-			if (_add_function(funcs, grp->settings[s].name))
+			ret = _add_function(funcs, pctl->desc.npins,
+					    grp->settings[s].name);
+			if (ret == -EOVERFLOW)
+				dev_err(&pdev->dev,
+					"More functions than pins(%d)\n",
+					pctl->desc.npins);
+			if (ret)
 				continue;
 
 			num++;
 		}
 	}
 
-	/* with the number of unique functions and it's groups known,
-	   reallocate functions and assign group names */
-	funcs = krealloc(funcs, num * sizeof(struct mvebu_pinctrl_function),
-			 GFP_KERNEL);
-	if (!funcs)
-		return -ENOMEM;
-
 	pctl->num_functions = num;
 	pctl->functions = funcs;
 

-- 
dwmw2


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