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Commit eee06c56 authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Theodore Ts'o
Browse files

jbd2: fix block tag checksum verification brokenness 



Al Viro complained of a ton of bogosity with regards to the jbd2 block
tag header checksum.  This one checksum is 16 bits, so cut off the
upper 16 bits and treat it as a 16-bit value and don't mess around
with be32* conversions.  Fortunately metadata checksumming is still
"experimental" and not in a shipping e2fsprogs, so there should be few
users affected by this.

Reported-by: default avatarAl Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent 5d9cf9c6

fs/jbd2/commit.c

+7 −6
Original line number Diff line number Diff line
@@ -343,20 +343,21 @@ static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag, 
{

	struct page *page = bh->b_page;

	__u8 *addr;

	__u32 csum;

	__u32 csum32;



	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))

		return;



	sequence = cpu_to_be32(sequence);

	addr = kmap_atomic(page);

	csum = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&sequence,

	csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&sequence,

			     sizeof(sequence));

	csum = jbd2_chksum(j, csum, addr + offset_in_page(bh->b_data),

	csum32 = jbd2_chksum(j, csum32, addr + offset_in_page(bh->b_data),

			     bh->b_size);

	kunmap_atomic(addr);



	tag->t_checksum = cpu_to_be32(csum);

	/* We only have space to store the lower 16 bits of the crc32c. */

	tag->t_checksum = cpu_to_be16(csum32);

}

/*

 * jbd2_journal_commit_transaction

fs/jbd2/recovery.c

+5 −6
Original line number Diff line number Diff line
@@ -399,18 +399,17 @@ static int jbd2_commit_block_csum_verify(journal_t *j, void *buf) 
static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,

				      void *buf, __u32 sequence)

{

	__u32 provided, calculated;

	__u32 csum32;



	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))

		return 1;



	sequence = cpu_to_be32(sequence);

	calculated = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&sequence,

	csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&sequence,

			     sizeof(sequence));

	calculated = jbd2_chksum(j, calculated, buf, j->j_blocksize);

	provided = be32_to_cpu(tag->t_checksum);

	csum32 = jbd2_chksum(j, csum32, buf, j->j_blocksize);



	return provided == cpu_to_be32(calculated);

	return tag->t_checksum == cpu_to_be16(csum32);

}



static int do_one_pass(journal_t *journal,