From: Theodore Ts'o Subject: [PATCH 4/4] ext4: fix overflow when counting used blocks on 32-bit architectures Date: Tue, 9 Jul 2013 10:39:32 -0400 Message-ID: <1373380772-16803-4-git-send-email-tytso@mit.edu> References: <20130709143855.GF6000@thunk.org> <1373380772-16803-1-git-send-email-tytso@mit.edu> Cc: Ext4 Developers List , Jan Kara , Theodore Ts'o To: stable@vger.kernel.org Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:36216 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753882Ab3GIOjf (ORCPT ); Tue, 9 Jul 2013 10:39:35 -0400 In-Reply-To: <1373380772-16803-1-git-send-email-tytso@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: From: Jan Kara 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 Signed-off-by: Theodore Ts'o --- 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 0fca5a8..38f03dc 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4702,7 +4702,7 @@ 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); @@ -4720,7 +4720,7 @@ 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; } -- 1.7.12.rc0.22.gcdd159b