linux-kernel - Re: [BUG] physmap_flash_probe() frees memory still in use

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Date:	Sat, 31 Jan 2009 00:52:50 +0900 (JST)
From:	Atsushi Nemoto <anemo@....ocn.ne.jp>
To:	matthias@...hlcke.net
Cc:	akpm@...ux-foundation.org, David.Woodhouse@...el.com,
	vapier.adi@...il.com, linux-mtd@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [BUG] physmap_flash_probe() frees memory still in use

On Fri, 30 Jan 2009 14:43:18 +0100, Matthias Kaehlcke <matthias@...hlcke.net> wrote:
> as i reported earlier in this month
> (http://lkml.org/lkml/2009/1/12/141) MTD partition names are screwed
> up in 2.6.29-rcX.
> 
> commit 176bf2e0f10ecf1d20a97db3bd5bb2e6ba0b5668 deals with a memory
> leak and frees the pointer array of mtd_partition after the call to
> add_mtd_partitions(). the problem is that mtd_table[x]->name still
> points to the freed memory.

Oh Yes, I had missed that point.  And looking at physmap driver again,
I found that del_mtd_partition() and del_mtd_device() are abused.
Though these APIs are robust enough, deleting right things in right
order would be better.

Could you test this patch?  I cannot test it until Monday.


------------------------------------------------------
Subject: [MTD] physmap: Fix wrong free and del_mtd_{partition,device}
From: Atsushi Nemoto <anemo@....ocn.ne.jp>

commit 176bf2e0f10ecf1d20a97db3bd5bb2e6ba0b5668 deals with a memory
leak and frees the pointer array of mtd_partition after the call to
add_mtd_partitions(). the problem is that mtd_table[x]->name still
points to the freed memory.

Aldo physmap_flash_remove() should call del_mtd_partitions() or
del_mtd_device() only once.

Reported-by: Matthias Kaehlcke <matthias@...hlcke.net>
Signed-off-by: Atsushi Nemoto <anemo@....ocn.ne.jp>
---
diff --git a/drivers/mtd/maps/physmap.c b/drivers/mtd/maps/physmap.c
index 8774366..4b122e7 100644
--- a/drivers/mtd/maps/physmap.c
+++ b/drivers/mtd/maps/physmap.c
@@ -29,6 +29,7 @@ struct physmap_flash_info {
 	struct map_info		map[MAX_RESOURCES];
 #ifdef CONFIG_MTD_PARTITIONS
 	int			nr_parts;
+	struct mtd_partition	*parts;
 #endif
 };
 
@@ -45,25 +46,26 @@ static int physmap_flash_remove(struct platform_device *dev)
 
 	physmap_data = dev->dev.platform_data;
 
-#ifdef CONFIG_MTD_CONCAT
-	if (info->cmtd != info->mtd[0]) {
+#ifdef CONFIG_MTD_PARTITIONS
+	if (info->nr_parts) {
+		del_mtd_partitions(info->cmtd);
+		kfree(info->parts);
+	} else if (physmap_data->nr_parts)
+		del_mtd_partitions(info->cmtd);
+	else
 		del_mtd_device(info->cmtd);
+#else
+	del_mtd_device(info->cmtd);
+#endif
+
+#ifdef CONFIG_MTD_CONCAT
+	if (info->cmtd != info->mtd[0])
 		mtd_concat_destroy(info->cmtd);
-	}
 #endif
 
 	for (i = 0; i < MAX_RESOURCES; i++) {
-		if (info->mtd[i] != NULL) {
-#ifdef CONFIG_MTD_PARTITIONS
-			if (info->nr_parts || physmap_data->nr_parts)
-				del_mtd_partitions(info->mtd[i]);
-			else
-				del_mtd_device(info->mtd[i]);
-#else
-			del_mtd_device(info->mtd[i]);
-#endif
+		if (info->mtd[i] != NULL)
 			map_destroy(info->mtd[i]);
-		}
 	}
 	return 0;
 }
@@ -86,9 +88,6 @@ static int physmap_flash_probe(struct platform_device *dev)
 	int err = 0;
 	int i;
 	int devices_found = 0;
-#ifdef CONFIG_MTD_PARTITIONS
-	struct mtd_partition *parts;
-#endif
 
 	physmap_data = dev->dev.platform_data;
 	if (physmap_data == NULL)
@@ -167,10 +166,11 @@ static int physmap_flash_probe(struct platform_device *dev)
 		goto err_out;
 
 #ifdef CONFIG_MTD_PARTITIONS
-	err = parse_mtd_partitions(info->cmtd, part_probe_types, &parts, 0);
+	err = parse_mtd_partitions(info->cmtd, part_probe_types,
+				&info->parts, 0);
 	if (err > 0) {
-		add_mtd_partitions(info->cmtd, parts, err);
-		kfree(parts);
+		add_mtd_partitions(info->cmtd, info->parts, err);
+		info->nr_parts = err;
 		return 0;
 	}
 
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