[U-Boot] [PATCH v2 1/4] fs/ext4: Fix group descriptor checksum calculation

[Tuomas Tynkkynen]

On 09/26/2017 06:25 PM, Tom Rini wrote:
> On Mon, Sep 25, 2017 at 10:06:31PM +0300, Tuomas Tynkkynen wrote:
>> The current code doesn't compute the group descriptor checksum correctly
>> for the filesystems that e2fsprogs 1.43.4 creates (they have
>> 'Group descriptor size: 64' as reported by tune2fs). Extend the checksum
>> calculation to be done as ext4_group_desc_csum() does in Linux.
>>
>> This fixes these errors in dmesg from running fs-test.sh and makes it
>> succeed again:
>>
>> [1671902.620699] EXT4-fs (loop1): ext4_check_descriptors: Checksum for group 0 failed (35782!=10965)
>> [1671902.620706] EXT4-fs (loop1): group descriptors corrupted!
>>
>> Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen at iki.fi>
>> ---
>> v2: New patch
>> ---
>>   fs/ext4/ext4_common.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
>> index 621c61e5c7..31952f48b9 100644
>> --- a/fs/ext4/ext4_common.c
>> +++ b/fs/ext4/ext4_common.c
>> @@ -432,6 +432,10 @@ uint16_t ext4fs_checksum_update(uint32_t i)
>>   		crc = ext2fs_crc16(crc, desc, offset);
>>   		offset += sizeof(desc->bg_checksum);	/* skip checksum */
>>   		assert(offset == sizeof(*desc));
>> +		if (offset < fs->gdsize) {
>> +			crc = ext2fs_crc16(crc, (__u8 *)desc + offset,
>> +					   fs->gdsize - offset);
>> +		}
> 
> This would be feb0ab32a57e4e6c8b24f6fb68f0ce08efe4603c from the kernel?

No, it goes further back, to 2007 even(!): 717d50e4971b81b96c0199c91cdf0

> So shouldn't we have le16_to_cpu on fs->gdsize ?  Or did I read over the
> 'git log -p' output in the kernel too quickly?  Thanks!
> 

No, because fs->gdsize is already endian-swapped elsewhere:

> 2345                 fs->gdsize = le32_to_cpu(data->sblock.feature_incompat) &
> 2346                         EXT4_FEATURE_INCOMPAT_64BIT ?
> 2347                         le16_to_cpu(data->sblock.descriptor_size) : 32;