bcachefs: fix unsafety in bch2_stripe_to_text()

.to_text() functions need to work on key values that didn't pass .valid
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/ec.c

@@ -131,29 +131,33 @@ int bch2_stripe_invalid(struct bch_fs *c, struct bkey_s_c k,
 void bch2_stripe_to_text(struct printbuf *out, struct bch_fs *c,
 			 struct bkey_s_c k)
 {
-	const struct bch_stripe *s = bkey_s_c_to_stripe(k).v;
-	unsigned i, nr_data = s->nr_blocks - s->nr_redundant;
+	const struct bch_stripe *sp = bkey_s_c_to_stripe(k).v;
+	struct bch_stripe s = {};
+
+	memcpy(&s, sp, min(sizeof(s), bkey_val_bytes(k.k)));
+
+	unsigned nr_data = s.nr_blocks - s.nr_redundant;
 
 	prt_printf(out, "algo %u sectors %u blocks %u:%u csum %u gran %u",
-	       s->algorithm,
-	       le16_to_cpu(s->sectors),
+		   s.algorithm,
+		   le16_to_cpu(s.sectors),
 		   nr_data,
-	       s->nr_redundant,
-	       s->csum_type,
-	       1U << s->csum_granularity_bits);
+		   s.nr_redundant,
+		   s.csum_type,
+		   1U << s.csum_granularity_bits);
 
-	for (i = 0; i < s->nr_blocks; i++) {
-		const struct bch_extent_ptr *ptr = s->ptrs + i;
-		struct bch_dev *ca = bch_dev_bkey_exists(c, ptr->dev);
-		u32 offset;
-		u64 b = sector_to_bucket_and_offset(ca, ptr->offset, &offset);
-
-		prt_printf(out, " %u:%llu:%u", ptr->dev, b, offset);
-		if (i < nr_data)
-			prt_printf(out, "#%u", stripe_blockcount_get(s, i));
-		prt_printf(out, " gen %u", ptr->gen);
-		if (ptr_stale(ca, ptr))
-			prt_printf(out, " stale");
+	for (unsigned i = 0; i < s.nr_blocks; i++) {
+		const struct bch_extent_ptr *ptr = sp->ptrs + i;
+
+		if ((void *) ptr >= bkey_val_end(k))
+			break;
+
+		bch2_extent_ptr_to_text(out, c, ptr);
+
+		if (s.csum_type < BCH_CSUM_NR &&
+		    i < nr_data &&
+		    stripe_blockcount_offset(&s, i) < bkey_val_bytes(k.k))
+			prt_printf(out,  "#%u", stripe_blockcount_get(sp, i));
 	}
 }
 

fs/bcachefs/ec.h

@@ -32,6 +32,8 @@ static inline unsigned stripe_csums_per_device(const struct bch_stripe *s)
 static inline unsigned stripe_csum_offset(const struct bch_stripe *s,
 					  unsigned dev, unsigned csum_idx)
 {
+	EBUG_ON(s->csum_type >= BCH_CSUM_NR);
+
 	unsigned csum_bytes = bch_crc_bytes[s->csum_type];
 
 	return sizeof(struct bch_stripe) +