linux-ext4 - [PATCH] ext4: memory leakage in ext4_mb_free

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Date:	Wed, 24 Mar 2010 21:55:55 +0800
From:	jing zhang <zj.barak@...il.com>
To:	linux-ext4 <linux-ext4@...r.kernel.org>
Cc:	"Theodore Ts'o" <tytso@....edu>, Andreas Dilger <adilger@....com>,
	Dave Kleikamp <shaggy@...ux.vnet.ibm.com>
Subject: [PATCH] ext4: memory leakage in ext4_mb_free_blocks()

From: Jing Zhang <zj.barak@...il.com>

Date: Wed Mar 24 21:54:22     2010

There is memory leakage in ext4_mb_free_blocks(), if error, double
free of blocks, occurs in ext4_mb_free_metadata().

Cc: Theodore Ts'o <tytso@....edu>
Cc: Andreas Dilger <adilger@....com>
Cc: Dave Kleikamp <shaggy@...ux.vnet.ibm.com>
Signed-off-by: Jing Zhang <zj.barak@...il.com>

---

--- linux-2.6.32/fs/ext4/mballoc.c	2009-12-03 11:51:22.000000000 +0800
+++ ext4_mm_leak/mballoc8.c	2010-03-24 21:46:50.000000000 +0800
@@ -4419,7 +4419,8 @@ ext4_mb_free_metadata(handle_t *handle,
 	spin_lock(&sbi->s_md_lock);
 	list_add(&new_entry->list, &handle->h_transaction->t_private_list);
 	spin_unlock(&sbi->s_md_lock);
-	return 0;
+	/* info the caller new_entry is used */
+	return 1;
 }

 /*
@@ -4547,7 +4548,8 @@ do_more:

 		ext4_lock_group(sb, block_group);
 		mb_clear_bits(bitmap_bh->b_data, bit, count);
-		ext4_mb_free_metadata(handle, &e4b, new_entry);
+		if (0 == ext4_mb_free_metadata(handle, &e4b, new_entry))
+			kmem_cache_free(ext4_free_ext_cachep, new_entry);
 	} else {
 		/* need to update group_info->bb_free and bitmap
 		 * with group lock held. generate_buddy look at
--
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