btrfs: fix uninitialized parent in insert_state

I don't know how this isn't caught when we build this in the kernel, but
while syncing extent-io-tree.c into btrfs-progs I got an error because
parent could potentially be uninitialized when we link in a new node,
specifically when the extent_io_tree is empty.  This means we could have
garbage in the parent color.  I don't know what the ramifications are of
that, but it's probably not great, so fix this by initializing parent to
NULL.  I spot checked all of our other usages in btrfs and we appear to
be doing the correct thing everywhere else.

Fixes: c7e118cf98c7 ("btrfs: open code rbtree search in insert_state")
CC: stable@vger.kernel.org # 6.0+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent-io-tree.c b/fs/btrfs/extent-io-tree.c
index 21fa15123af8088e60b2efbf69bb65964f49bc9f..82ca6a11e11a2b2ec0ff3c0ffc1a4606348286d5 100644 (file)
--- a/fs/btrfs/extent-io-tree.c
+++ b/fs/btrfs/extent-io-tree.c
@@ -395,7 +395,7 @@ static int insert_state(struct extent_io_tree *tree,
                        u32 bits, struct extent_changeset *changeset)
 {
        struct rb_node **node;
-       struct rb_node *parent;
+       struct rb_node *parent = NULL;
        const u64 end = state->end;
 
        set_state_bits(tree, state, bits, changeset);