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authorDaeho Jeong <daeho.jeong@samsung.com>2016-07-04 00:51:39 +0300
committerTheodore Ts'o <tytso@mit.edu>2016-07-04 00:51:39 +0300
commitb47820edd1634dc1208f9212b7ecfb4230610a23 (patch)
tree7d02e4756db46ae94ec43fdcd1adfd38156e34a5 /fs/ext4/namei.c
parentf70749ca42943faa4d4dcce46dfdcaadb1d0c4b6 (diff)
downloadlinux-b47820edd1634dc1208f9212b7ecfb4230610a23.tar.xz
ext4: avoid modifying checksum fields directly during checksum verification
We temporally change checksum fields in buffers of some types of metadata into '0' for verifying the checksum values. By doing this without locking the buffer, some metadata's checksums, which are being committed or written back to the storage, could be damaged. In our test, several metadata blocks were found with damaged metadata checksum value during recovery process. When we only verify the checksum value, we have to avoid modifying checksum fields directly. Signed-off-by: Daeho Jeong <daeho.jeong@samsung.com> Signed-off-by: Youngjin Gil <youngjin.gil@samsung.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/ext4/namei.c')
-rw-r--r--fs/ext4/namei.c9
1 files changed, 4 insertions, 5 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index ec4c39952e84..5bb46b6ed456 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -420,15 +420,14 @@ static __le32 ext4_dx_csum(struct inode *inode, struct ext4_dir_entry *dirent,
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
struct ext4_inode_info *ei = EXT4_I(inode);
__u32 csum;
- __le32 save_csum;
int size;
+ __u32 dummy_csum = 0;
+ int offset = offsetof(struct dx_tail, dt_checksum);
size = count_offset + (count * sizeof(struct dx_entry));
- save_csum = t->dt_checksum;
- t->dt_checksum = 0;
csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)dirent, size);
- csum = ext4_chksum(sbi, csum, (__u8 *)t, sizeof(struct dx_tail));
- t->dt_checksum = save_csum;
+ csum = ext4_chksum(sbi, csum, (__u8 *)t, offset);
+ csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, sizeof(dummy_csum));
return cpu_to_le32(csum);
}