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| author | Daeho Jeong <daeho.jeong@samsung.com> | 2016-07-03 17:51:39 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2016-07-03 17:51:39 -0400 |
| commit | b47820edd1634dc1208f9212b7ecfb4230610a23 (patch) | |
| tree | 7d02e4756db46ae94ec43fdcd1adfd38156e34a5 /fs/ext4/super.c | |
| parent | f70749ca42943faa4d4dcce46dfdcaadb1d0c4b6 (diff) | |
| download | linux-b47820edd1634dc1208f9212b7ecfb4230610a23.tar.gz | |
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/super.c')
| -rw-r--r-- | fs/ext4/super.c | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 3822a5aedc61..6e2f9d628c48 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2068,23 +2068,25 @@ failed: static __le16 ext4_group_desc_csum(struct super_block *sb, __u32 block_group, struct ext4_group_desc *gdp) { - int offset; + int offset = offsetof(struct ext4_group_desc, bg_checksum); __u16 crc = 0; __le32 le_group = cpu_to_le32(block_group); struct ext4_sb_info *sbi = EXT4_SB(sb); if (ext4_has_metadata_csum(sbi->s_sb)) { /* Use new metadata_csum algorithm */ - __le16 save_csum; __u32 csum32; + __u16 dummy_csum = 0; - save_csum = gdp->bg_checksum; - gdp->bg_checksum = 0; csum32 = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&le_group, sizeof(le_group)); - csum32 = ext4_chksum(sbi, csum32, (__u8 *)gdp, - sbi->s_desc_size); - gdp->bg_checksum = save_csum; + csum32 = ext4_chksum(sbi, csum32, (__u8 *)gdp, offset); + csum32 = ext4_chksum(sbi, csum32, (__u8 *)&dummy_csum, + sizeof(dummy_csum)); + offset += sizeof(dummy_csum); + if (offset < sbi->s_desc_size) + csum32 = ext4_chksum(sbi, csum32, (__u8 *)gdp + offset, + sbi->s_desc_size - offset); crc = csum32 & 0xFFFF; goto out; @@ -2094,8 +2096,6 @@ static __le16 ext4_group_desc_csum(struct super_block *sb, __u32 block_group, if (!ext4_has_feature_gdt_csum(sb)) return 0; - offset = offsetof(struct ext4_group_desc, bg_checksum); - crc = crc16(~0, sbi->s_es->s_uuid, sizeof(sbi->s_es->s_uuid)); crc = crc16(crc, (__u8 *)&le_group, sizeof(le_group)); crc = crc16(crc, (__u8 *)gdp, offset); |