Commit 602ce7b8 authored Jan 27, 2023 by Ryusuke Konishi Committed by Andrew Morton Feb 02, 2023

nilfs2: prevent WARNING in nilfs_dat_commit_end()

If nilfs2 reads a corrupted disk image and its DAT metadata file contains
invalid lifetime data for a virtual block number, a kernel warning can be
generated by the WARN_ON check in nilfs_dat_commit_end() and can panic if
the kernel is booted with panic_on_warn.

This patch avoids the issue with a sanity check that treats it as an
error.

Since error return is not allowed in the execution phase of
nilfs_dat_commit_end(), this inserts that sanity check in
nilfs_dat_prepare_end(), which prepares for nilfs_dat_commit_end().

As the error code, -EINVAL is returned to notify bmap layer of the
metadata corruption. When the bmap layer sees this code, it handles the
abnormal situation and replaces the return code with -EIO as it should.

Link: https://lkml.kernel.org/r/000000000000154d2c05e9ec7df6@google.com
Link: https://lkml.kernel.org/r/20230127132202.6083-1-konishi.ryusuke@gmail.com

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: <syzbot+cbff7a52b6f99059e67f@syzkaller.appspotmail.com>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent e89bd9e7

fs/nilfs2/dat.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -158,6 +158,7 @@ void nilfs_dat_commit_start(struct inode dat, struct nilfs_palloc_req req,
		int nilfs_dat_prepare_end(struct inode dat, struct nilfs_palloc_req req)
		{
		struct nilfs_dat_entry *entry;
		__u64 start;
		sector_t blocknr;
		void *kaddr;
		int ret;
		@@ -169,6 +170,7 @@ int nilfs_dat_prepare_end(struct inode dat, struct nilfs_palloc_req req)
		kaddr = kmap_atomic(req->pr_entry_bh->b_page);
		entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
		req->pr_entry_bh, kaddr);
		start = le64_to_cpu(entry->de_start);
		blocknr = le64_to_cpu(entry->de_blocknr);
		kunmap_atomic(kaddr);

		@@ -179,6 +181,15 @@ int nilfs_dat_prepare_end(struct inode dat, struct nilfs_palloc_req req)
		return ret;
		}
		}
		if (unlikely(start > nilfs_mdt_cno(dat))) {
		nilfs_err(dat->i_sb,
		"vblocknr = %llu has abnormal lifetime: start cno (= %llu) > current cno (= %llu)",
		(unsigned long long)req->pr_entry_nr,
		(unsigned long long)start,
		(unsigned long long)nilfs_mdt_cno(dat));
		nilfs_dat_abort_entry(dat, req);
		return -EINVAL;
		}

		return 0;
		}