linux-kernel - [ 17/32] ext4: avoid kmemcheck complaint from reading uninitialized memory

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Message-Id: <20120820035650.242768924@linuxfoundation.org>
Date:	Sun, 19 Aug 2012 20:57:13 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, "Theodore Tso" <tytso@....edu>
Subject: [ 17/32] ext4: avoid kmemcheck complaint from reading uninitialized memory

From: Greg KH <gregkh@...uxfoundation.org>

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Theodore Ts'o <tytso@....edu>

commit 7e731bc9a12339f344cddf82166b82633d99dd86 upstream.

Commit 03179fe923 introduced a kmemcheck complaint in
ext4_da_get_block_prep() because we save and restore
ei->i_da_metadata_calc_last_lblock even though it is left
uninitialized in the case where i_da_metadata_calc_len is zero.

This doesn't hurt anything, but silencing the kmemcheck complaint
makes it easier for people to find real bugs.

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=45631
(which is marked as a regression).

Signed-off-by: "Theodore Ts'o" <tytso@....edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/ext4/super.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -932,6 +932,7 @@ static struct inode *ext4_alloc_inode(st
 	ei->i_reserved_meta_blocks = 0;
 	ei->i_allocated_meta_blocks = 0;
 	ei->i_da_metadata_calc_len = 0;
+	ei->i_da_metadata_calc_last_lblock = 0;
 	spin_lock_init(&(ei->i_block_reservation_lock));
 #ifdef CONFIG_QUOTA
 	ei->i_reserved_quota = 0;


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