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Commit 5278c3eb authored by Ryusuke Konishi's avatar Ryusuke Konishi Committed by Greg Kroah-Hartman
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nilfs2: fix data corruption in dsync block recovery for small block sizes 

commit 67b8bcbaed4777871bb0dcc888fb02a614a98ab1 upstream.

The helper function nilfs_recovery_copy_block() of
nilfs_recovery_dsync_blocks(), which recovers data from logs created by
data sync writes during a mount after an unclean shutdown, incorrectly
calculates the on-page offset when copying repair data to the file's page
cache.  In environments where the block size is smaller than the page
size, this flaw can cause data corruption and leak uninitialized memory
bytes during the recovery process.

Fix these issues by correcting this byte offset calculation on the page.

Link: https://lkml.kernel.org/r/20240124121936.10575-1-konishi.ryusuke@gmail.com


Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@gmail.com>
Tested-by: default avatarRyusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e0de24ef

fs/nilfs2/recovery.c

+4 −3
Original line number Diff line number Diff line
@@ -472,9 +472,10 @@ static int nilfs_prepare_segment_for_recovery(struct the_nilfs *nilfs, 


static int nilfs_recovery_copy_block(struct the_nilfs *nilfs,

				     struct nilfs_recovery_block *rb,

				     struct page *page)

				     loff_t pos, struct page *page)

{

	struct buffer_head *bh_org;

	size_t from = pos & ~PAGE_MASK;

	void *kaddr;



	bh_org = __bread(nilfs->ns_bdev, rb->blocknr, nilfs->ns_blocksize);
@@ -482,7 +483,7 @@ static int nilfs_recovery_copy_block(struct the_nilfs *nilfs, 
		return -EIO;



	kaddr = kmap_atomic(page);

	memcpy(kaddr + bh_offset(bh_org), bh_org->b_data, bh_org->b_size);

	memcpy(kaddr + from, bh_org->b_data, bh_org->b_size);

	kunmap_atomic(kaddr);

	brelse(bh_org);

	return 0;
@@ -521,7 +522,7 @@ static int nilfs_recover_dsync_blocks(struct the_nilfs *nilfs, 
			goto failed_inode;

		}



		err = nilfs_recovery_copy_block(nilfs, rb, page);

		err = nilfs_recovery_copy_block(nilfs, rb, pos, page);

		if (unlikely(err))

			goto failed_page;