| Message ID | 062d63c8-39bf-62d8-4562-625184e97b6c@I-love.SAKURA.ne.jp (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: Call btrfs_set_header_generation() before btrfs_clean_tree_block() | expand |
On 20.09.22 13:49, Tetsuo Handa wrote: > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index 6914cd8024ba..9c7bf0ef6a5f 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -4895,6 +4895,7 @@ btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root, > */ > btrfs_set_buffer_lockdep_class(lockdep_owner, buf, level); > > + btrfs_set_header_generation(buf, trans->transid); Here you're setting the header generation into the extent buffer > __btrfs_tree_lock(buf, nest); > btrfs_clean_tree_block(buf); > clear_bit(EXTENT_BUFFER_STALE, &buf->bflags); > @@ -4905,7 +4906,6 @@ btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root, > memzero_extent_buffer(buf, 0, sizeof(struct btrfs_header)); And here the extent buffer's part containing the header gets memzeroed resulting in header generation 0. Fo rthis to poroperly work you'd need to bring the memzero_extent_buffer() call before setting the header generation or re-set the generation after clearing. > btrfs_set_header_level(buf, level); > btrfs_set_header_bytenr(buf, buf->start); > - btrfs_set_header_generation(buf, trans->transid); > btrfs_set_header_backref_rev(buf, BTRFS_MIXED_BACKREF_REV); > btrfs_set_header_owner(buf, owner); > write_extent_buffer_fsid(buf, fs_info->fs_devices->metadata_uuid);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 6914cd8024ba..9c7bf0ef6a5f 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -4895,6 +4895,7 @@ btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root, */ btrfs_set_buffer_lockdep_class(lockdep_owner, buf, level); + btrfs_set_header_generation(buf, trans->transid); __btrfs_tree_lock(buf, nest); btrfs_clean_tree_block(buf); clear_bit(EXTENT_BUFFER_STALE, &buf->bflags); @@ -4905,7 +4906,6 @@ btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root, memzero_extent_buffer(buf, 0, sizeof(struct btrfs_header)); btrfs_set_header_level(buf, level); btrfs_set_header_bytenr(buf, buf->start); - btrfs_set_header_generation(buf, trans->transid); btrfs_set_header_backref_rev(buf, BTRFS_MIXED_BACKREF_REV); btrfs_set_header_owner(buf, owner); write_extent_buffer_fsid(buf, fs_info->fs_devices->metadata_uuid);
syzbot is reporting uninit-value in btrfs_clean_tree_block() [1], for commit bc877d285ca3dba2 ("btrfs: Deduplicate extent_buffer init code") missed that btrfs_set_header_generation() in btrfs_init_new_buffer() must not be moved to after clean_tree_block() because clean_tree_block() is calling btrfs_header_generation() since commit 55c69072d6bd5be1 ("Btrfs: Fix extent_buffer usage when nodesize != leafsize"). Link: https://syzkaller.appspot.com/bug?extid=fba8e2116a12609b6c59 [1] Reported-by: syzbot <syzbot+fba8e2116a12609b6c59@syzkaller.appspotmail.com> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Fixes: bc877d285ca3dba2 ("btrfs: Deduplicate extent_buffer init code") --- This patch is not tested due to lack of reproducer. I don't know whether initializing only generation field is sufficient. Please check before applying. fs/btrfs/extent-tree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)