From: Jan Kara Subject: [PATCH 4/4] ext4: Fix overflow when counting used blocks on 32-bit architectures Date: Wed, 29 May 2013 14:05:33 +0200 Message-ID: <1369829133-4307-5-git-send-email-jack@suse.cz> References: <1369829133-4307-1-git-send-email-jack@suse.cz> Cc: linux-ext4@vger.kernel.org, Jan Kara To: Ted Tso Return-path: Received: from cantor2.suse.de ([195.135.220.15]:52121 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965833Ab3E2MFl (ORCPT ); Wed, 29 May 2013 08:05:41 -0400 In-Reply-To: <1369829133-4307-1-git-send-email-jack@suse.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: The arithmetics adding delalloc blocks to the number of used blocks in ext4_getattr() can easily overflow on 32-bit archs as we first multiply number of blocks by blocksize and then divide back by 512. Make the arithmetics more clever and also use proper type (unsigned long long instead of unsigned long). Signed-off-by: Jan Kara --- fs/ext4/inode.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index d6382b8..83d9e69 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4805,7 +4805,7 @@ int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) { struct inode *inode; - unsigned long delalloc_blocks; + unsigned long long delalloc_blocks; inode = dentry->d_inode; generic_fillattr(inode, stat); @@ -4823,7 +4823,7 @@ int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry, delalloc_blocks = EXT4_C2B(EXT4_SB(inode->i_sb), EXT4_I(inode)->i_reserved_data_blocks); - stat->blocks += (delalloc_blocks << inode->i_sb->s_blocksize_bits)>>9; + stat->blocks += delalloc_blocks << (inode->i_sb->s_blocksize_bits-9); return 0; } -- 1.8.1.4