From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
commit cbddcc4fa3443fe8cfb2ff8e210deb1f6a0eea38 upstream.
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").
Since memzero_extent_buffer() will reset "struct btrfs_header" part, we can't move btrfs_set_header_generation() to before memzero_extent_buffer(). Just re-add btrfs_set_header_generation() before btrfs_clean_tree_block().
Link: https://syzkaller.appspot.com/bug?extid=fba8e2116a12609b6c59 [1] Reported-by: syzbot syzbot+fba8e2116a12609b6c59@syzkaller.appspotmail.com Fixes: bc877d285ca3dba2 ("btrfs: Deduplicate extent_buffer init code") CC: stable@vger.kernel.org # 4.19+ Signed-off-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/extent-tree.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -4904,6 +4904,9 @@ btrfs_init_new_buffer(struct btrfs_trans !test_bit(BTRFS_ROOT_RESET_LOCKDEP_CLASS, &root->state)) lockdep_owner = BTRFS_FS_TREE_OBJECTID;
+ /* btrfs_clean_tree_block() accesses generation field. */ + btrfs_set_header_generation(buf, trans->transid); + /* * This needs to stay, because we could allocate a freed block from an * old tree into a new tree, so we need to make sure this new block is