bcachefs: Array bounds fixes

It's no longer legal to use a zero size array as a flexible array
member - this causes UBSAN to complain.

This patch switches our zero size arrays to normal flexible array
members when possible, and inserts casts in other places (e.g. where we
use the zero size array as a marker partway through an array).

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 10 insertions, 11 deletions

diff --git a/fs/bcachefs/btree_io.c b/fs/bcachefs/btree_io.c
index cba3c081b1d0..0edbb73a5ec8 100644
--- a/fs/bcachefs/btree_io.c
+++ b/fs/bcachefs/btree_io.c
@@ -292,7 +292,7 @@ static void btree_node_sort(struct bch_fs *c, struct btree *b,
 			    bool filter_whiteouts)
 {
 	struct btree_node *out;
-	struct sort_iter sort_iter;
+	struct sort_iter_stack sort_iter;
 	struct bset_tree *t;
 	struct bset *start_bset = bset(b, &b->set[start_idx]);
 	bool used_mempool = false;
@@ -301,13 +301,13 @@ static void btree_node_sort(struct bch_fs *c, struct btree *b,
 	bool sorting_entire_node = start_idx == 0 &&
 		end_idx == b->nsets;
 
-	sort_iter_init(&sort_iter, b);
+	sort_iter_stack_init(&sort_iter, b);
 
 	for (t = b->set + start_idx;
 	     t < b->set + end_idx;
 	     t++) {
 		u64s += le16_to_cpu(bset(b, t)->u64s);
-		sort_iter_add(&sort_iter,
+		sort_iter_add(&sort_iter.iter,
 			      btree_bkey_first(b, t),
 			      btree_bkey_last(b, t));
 	}
@@ -320,7 +320,7 @@ static void btree_node_sort(struct bch_fs *c, struct btree *b,
 
 	start_time = local_clock();
 
-	u64s = bch2_sort_keys(out->keys.start, &sort_iter, filter_whiteouts);
+	u64s = bch2_sort_keys(out->keys.start, &sort_iter.iter, filter_whiteouts);
 
 	out->keys.u64s = cpu_to_le16(u64s);
 
@@ -918,8 +918,7 @@ int bch2_btree_node_read_done(struct bch_fs *c, struct bch_dev *ca,
 	b->written = 0;
 
 	iter = mempool_alloc(&c->fill_iter, GFP_NOFS);
-	sort_iter_init(iter, b);
-	iter->size = (btree_blocks(c) + 1) * 2;
+	sort_iter_init(iter, b, (btree_blocks(c) + 1) * 2);
 
 	if (bch2_meta_read_fault("btree"))
 		btree_err(-BCH_ERR_btree_node_read_err_must_retry, c, ca, b, NULL,
@@ -1852,7 +1851,7 @@ void __bch2_btree_node_write(struct bch_fs *c, struct btree *b, unsigned flags)
 	struct bset *i;
 	struct btree_node *bn = NULL;
 	struct btree_node_entry *bne = NULL;
-	struct sort_iter sort_iter;
+	struct sort_iter_stack sort_iter;
 	struct nonce nonce;
 	unsigned bytes_to_write, sectors_to_write, bytes, u64s;
 	u64 seq = 0;
@@ -1925,7 +1924,7 @@ do_write:
 
 	bch2_sort_whiteouts(c, b);
 
-	sort_iter_init(&sort_iter, b);
+	sort_iter_stack_init(&sort_iter, b);
 
 	bytes = !b->written
 		? sizeof(struct btree_node)
@@ -1940,7 +1939,7 @@ do_write:
 			continue;
 
 		bytes += le16_to_cpu(i->u64s) * sizeof(u64);
-		sort_iter_add(&sort_iter,
+		sort_iter_add(&sort_iter.iter,
 			      btree_bkey_first(b, t),
 			      btree_bkey_last(b, t));
 		seq = max(seq, le64_to_cpu(i->journal_seq));
@@ -1969,14 +1968,14 @@ do_write:
 	i->journal_seq	= cpu_to_le64(seq);
 	i->u64s		= 0;
 
-	sort_iter_add(&sort_iter,
+	sort_iter_add(&sort_iter.iter,
 		      unwritten_whiteouts_start(c, b),
 		      unwritten_whiteouts_end(c, b));
 	SET_BSET_SEPARATE_WHITEOUTS(i, false);
 
 	b->whiteout_u64s = 0;
 
-	u64s = bch2_sort_keys(i->start, &sort_iter, false);
+	u64s = bch2_sort_keys(i->start, &sort_iter.iter, false);
 	le16_add_cpu(&i->u64s, u64s);
 
 	BUG_ON(!b->written && i->u64s != b->data->keys.u64s);