Re: possible memory leak in commands/nand.c?

[Sascha Hauer <s.hauer@pengutronix.de>]

On Sun, Dec 20, 2009 at 02:33:11PM -0500, Robert P. J. Day wrote:
> 
>   once again, perhaps i'm just misreading this but consider this code
> from commands/nand.c, noting the two early calls to asprintf():
> 
> ===== begin =====
> 
>         bb = xzalloc(sizeof(*bb));
>         bb->devname = asprintf("/dev/%s", basename(path));
>         if (name)
>                 bb->cdev.name = strdup(name);
>         else
>                 bb->cdev.name = asprintf("%s.bb", basename(path));
> 
>         ret = stat(bb->devname, &s);
>         if (ret)
>                 goto free_out;
> 
>         bb->raw_size = s.st_size;
> 
>         bb->fd = open(bb->devname, O_RDWR);
>         if (bb->fd < 0) {
>                 ret = -ENODEV;
>                 goto free_out;
>         }
> 
>         ret = ioctl(bb->fd, MEMGETINFO, &bb->info);
>         if (ret)
>                 goto free_out;
> 
>         nand_bb_calc_size(bb);
>         bb->cdev.ops = &nand_bb_ops;
>         bb->cdev.priv = bb;
> 
>         devfs_create(&bb->cdev);
> 
>         return 0;
> 
> free_out:
>         free(bb);
>         return ret;
> 
> ===== end =====
> 
>   if something in the latter part of that code fails and control jumps
> to the label "free_out", won't this code fail to free() the memory
> allocated in the two asprintf() calls?  isn't the programmer
> explicitly required to free memory allocated with asprintf() or
> vasprintf() calls?

Yes, indeed, that's a memory hole here. The following should fix this.
Thanks for noting.

Sascha


From 4e4b03cd61808383a98cb1d10a47025e1909e0bd Mon Sep 17 00:00:00 2001
From: Sascha Hauer <s.hauer@pengutronix.de>
Date: Mon, 21 Dec 2009 09:41:52 +0100
Subject: [PATCH] commands/nand.c: Fix memory hole

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 commands/nand.c |   22 +++++++++++++++++-----
 1 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/commands/nand.c b/commands/nand.c
index cbf1058..55b89af 100644
--- a/commands/nand.c
+++ b/commands/nand.c
@@ -224,31 +224,37 @@ static struct file_operations nand_bb_ops = {
 int dev_add_bb_dev(char *path, const char *name)
 {
 	struct nand_bb *bb;
-	int ret;
+	int ret = -ENOMEM;
 	struct stat s;
 
 	bb = xzalloc(sizeof(*bb));
 	bb->devname = asprintf("/dev/%s", basename(path));
+	if (!bb->devname)
+		goto out1;
+
 	if (name)
 		bb->cdev.name = strdup(name);
 	else
 		bb->cdev.name = asprintf("%s.bb", basename(path));
 
+	if (!bb->cdev.name)
+		goto out2;
+
 	ret = stat(bb->devname, &s);
 	if (ret)
-		goto free_out;
+		goto out3;
 
 	bb->raw_size = s.st_size;
 
 	bb->fd = open(bb->devname, O_RDWR);
 	if (bb->fd < 0) {
 		ret = -ENODEV;
-		goto free_out;
+		goto out3;
 	}
 
 	ret = ioctl(bb->fd, MEMGETINFO, &bb->info);
 	if (ret)
-		goto free_out;
+		goto out4;
 
 	nand_bb_calc_size(bb);
 	bb->cdev.ops = &nand_bb_ops;
@@ -258,7 +264,13 @@ int dev_add_bb_dev(char *path, const char *name)
 
 	return 0;
 
-free_out:
+out4:
+	close(bb->fd);
+out3:
+	free(bb->cdev.name);
+out2:
+	free(bb->devname);
+out1:
 	free(bb);
 	return ret;
 }
-- 
1.6.5.2


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