linux-ext4 - [PATCH] ext4: fix inode checksum calculation problem of inode in some range of inode size

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Date:   Wed, 23 Nov 2016 09:28:46 +0900
From:   Daeho Jeong <daeho.jeong@...sung.com>
To:     tytso@....edu, linux-ext4@...r.kernel.org
Cc:     Daeho Jeong <daeho.jeong@...sung.com>,
        Youngjin Gil <youngjin.gil@...sung.com>,
        "Darrick J. Wong" <darrick.wong@...cle.com>
Subject: [PATCH] ext4: fix inode checksum calculation problem of inode in some
 range of inode size

We've fixed the race condition problem in calculating ext4 checksum
value in commit b47820edd163 ("ext4: avoid modifying checksum fields
directly during checksum veficationon"). However, by this change,
when calculating the checksum value of inode whose i_extra_size is
less than 4, we couldn't calculate the checksum value in a proper way.
This problem was found and reported by Nix, Thank you.

Reported-by: Nix <nix@...eri.org.uk>
Signed-off-by: Daeho Jeong <daeho.jeong@...sung.com>
Signed-off-by: Youngjin Gil <youngjin.gil@...sung.com>
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
 fs/ext4/inode.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9c06472..eaab3c3 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -71,10 +71,9 @@ static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
 			csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum,
 					   csum_size);
 			offset += csum_size;
-			csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
-					   EXT4_INODE_SIZE(inode->i_sb) -
-					   offset);
 		}
+		csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
+				   EXT4_INODE_SIZE(inode->i_sb) - offset);
 	}
 
 	return csum;
-- 
1.7.9.5

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