This is a note to let you know that I've just added the patch titled
nilfs2: prevent WARNING in nilfs_sufile_set_segment_usage()
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nilfs2-prevent-warning-in-nilfs_sufile_set_segment_usage.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 675abf8df1353e0e3bde314993e0796c524cfbf0 Mon Sep 17 00:00:00 2001
From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Date: Tue, 5 Dec 2023 17:59:47 +0900
Subject: nilfs2: prevent WARNING in nilfs_sufile_set_segment_usage()
From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
commit 675abf8df1353e0e3bde314993e0796c524cfbf0 upstream.
If nilfs2 reads a disk image with corrupted segment usage metadata, and
its segment usage information is marked as an error for the segment at the
write location, nilfs_sufile_set_segment_usage() can trigger WARN_ONs
during log writing.
Segments newly allocated for writing with nilfs_sufile_alloc() will not
have this error flag set, but this unexpected situation will occur if the
segment indexed by either nilfs->ns_segnum or nilfs->ns_nextnum (active
segment) was marked in error.
Fix this issue by inserting a sanity check to treat it as a file system
corruption.
Since error returns are not allowed during the execution phase where
nilfs_sufile_set_segment_usage() is used, this inserts the sanity check
into nilfs_sufile_mark_dirty() which pre-reads the buffer containing the
segment usage record to be updated and sets it up in a dirty state for
writing.
In addition, nilfs_sufile_set_segment_usage() is also called when
canceling log writing and undoing segment usage update, so in order to
avoid issuing the same kernel warning in that case, in case of
cancellation, avoid checking the error flag in
nilfs_sufile_set_segment_usage().
Link: https://lkml.kernel.org/r/20231205085947.4431-1-konishi.ryusuke@xxxxxxxxx
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Reported-by: syzbot+14e9f834f6ddecece094@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=14e9f834f6ddecece094
Tested-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/nilfs2/sufile.c | 42 +++++++++++++++++++++++++++++++++++-------
1 file changed, 35 insertions(+), 7 deletions(-)
--- a/fs/nilfs2/sufile.c
+++ b/fs/nilfs2/sufile.c
@@ -513,15 +513,38 @@ int nilfs_sufile_mark_dirty(struct inode
down_write(&NILFS_MDT(sufile)->mi_sem);
ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0, &bh);
- if (!ret) {
- mark_buffer_dirty(bh);
- nilfs_mdt_mark_dirty(sufile);
- kaddr = kmap_atomic(bh->b_page);
- su = nilfs_sufile_block_get_segment_usage(sufile, segnum, bh, kaddr);
+ if (ret)
+ goto out_sem;
+
+ kaddr = kmap_atomic(bh->b_page);
+ su = nilfs_sufile_block_get_segment_usage(sufile, segnum, bh, kaddr);
+ if (unlikely(nilfs_segment_usage_error(su))) {
+ struct the_nilfs *nilfs = sufile->i_sb->s_fs_info;
+
+ kunmap_atomic(kaddr);
+ brelse(bh);
+ if (nilfs_segment_is_active(nilfs, segnum)) {
+ nilfs_error(sufile->i_sb,
+ "active segment %llu is erroneous",
+ (unsigned long long)segnum);
+ } else {
+ /*
+ * Segments marked erroneous are never allocated by
+ * nilfs_sufile_alloc(); only active segments, ie,
+ * the segments indexed by ns_segnum or ns_nextnum,
+ * can be erroneous here.
+ */
+ WARN_ON_ONCE(1);
+ }
+ ret = -EIO;
+ } else {
nilfs_segment_usage_set_dirty(su);
kunmap_atomic(kaddr);
+ mark_buffer_dirty(bh);
+ nilfs_mdt_mark_dirty(sufile);
brelse(bh);
}
+out_sem:
up_write(&NILFS_MDT(sufile)->mi_sem);
return ret;
}
@@ -548,9 +571,14 @@ int nilfs_sufile_set_segment_usage(struc
kaddr = kmap_atomic(bh->b_page);
su = nilfs_sufile_block_get_segment_usage(sufile, segnum, bh, kaddr);
- WARN_ON(nilfs_segment_usage_error(su));
- if (modtime)
+ if (modtime) {
+ /*
+ * Check segusage error and set su_lastmod only when updating
+ * this entry with a valid timestamp, not for cancellation.
+ */
+ WARN_ON_ONCE(nilfs_segment_usage_error(su));
su->su_lastmod = cpu_to_le64(modtime);
+ }
su->su_nblocks = cpu_to_le32(nblocks);
kunmap_atomic(kaddr);
Patches currently in stable-queue which might be from konishi.ryusuke@xxxxxxxxx are
queue-4.14/nilfs2-prevent-warning-in-nilfs_sufile_set_segment_usage.patch
queue-4.14/nilfs2-fix-missing-error-check-for-sb_set_blocksize-call.patch
