From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Mon, 17 Mar 2025 17:58:51 +0000 (-0400)
Subject: bcachefs: Validate bch_sb.offset field
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=92c7789a9ed892da60cb5da2bcb6278551e2eb34;p=users%2Fjedix%2Flinux-maple.git

bcachefs: Validate bch_sb.offset field

This was missed - but it needs to be correct for the superblock recovery
tool that scans the start and end of the device for backup superblocks:
we don't want to pick up superblocks that belong to a different
partition that starts at a different offset.

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

diff --git a/fs/bcachefs/errcode.h b/fs/bcachefs/errcode.h
index 493cae4efc37..cb27de6ffad6 100644
--- a/fs/bcachefs/errcode.h
+++ b/fs/bcachefs/errcode.h
@@ -231,6 +231,7 @@
 	x(BCH_ERR_invalid_sb,		invalid_sb_csum)			\
 	x(BCH_ERR_invalid_sb,		invalid_sb_block_size)			\
 	x(BCH_ERR_invalid_sb,		invalid_sb_uuid)			\
+	x(BCH_ERR_invalid_sb,		invalid_sb_offset)			\
 	x(BCH_ERR_invalid_sb,		invalid_sb_too_many_members)		\
 	x(BCH_ERR_invalid_sb,		invalid_sb_dev_idx)			\
 	x(BCH_ERR_invalid_sb,		invalid_sb_time_precision)		\
diff --git a/fs/bcachefs/super-io.c b/fs/bcachefs/super-io.c
index 2e86a04b49e0..f2e4428281a3 100644
--- a/fs/bcachefs/super-io.c
+++ b/fs/bcachefs/super-io.c
@@ -365,7 +365,8 @@ static int bch2_sb_compatible(struct bch_sb *sb, struct printbuf *out)
 	return 0;
 }
 
-int bch2_sb_validate(struct bch_sb *sb, enum bch_validate_flags flags, struct printbuf *out)
+int bch2_sb_validate(struct bch_sb *sb, u64 read_offset,
+		     enum bch_validate_flags flags, struct printbuf *out)
 {
 	struct bch_sb_field_members_v1 *mi;
 	enum bch_opt_id opt_id;
@@ -409,6 +410,13 @@ int bch2_sb_validate(struct bch_sb *sb, enum bch_validate_flags flags, struct pr
 		return -BCH_ERR_invalid_sb_uuid;
 	}
 
+	if (!(flags & BCH_VALIDATE_write) &&
+	    le64_to_cpu(sb->offset) != read_offset) {
+		prt_printf(out, "Bad sb offset (got %llu, read from %llu)",
+			   le64_to_cpu(sb->offset), read_offset);
+		return -BCH_ERR_invalid_sb_offset;
+	}
+
 	if (!sb->nr_devices ||
 	    sb->nr_devices > BCH_SB_MEMBERS_MAX) {
 		prt_printf(out, "Bad number of member devices %u (max %u)",
@@ -888,7 +896,7 @@ got_super:
 
 	sb->have_layout = true;
 
-	ret = bch2_sb_validate(sb->sb, 0, &err);
+	ret = bch2_sb_validate(sb->sb, offset, 0, &err);
 	if (ret) {
 		bch2_print_opts(opts, KERN_ERR "bcachefs (%s): error validating superblock: %s\n",
 				path, err.buf);
@@ -1045,7 +1053,7 @@ int bch2_write_super(struct bch_fs *c)
 	darray_for_each(online_devices, ca) {
 		printbuf_reset(&err);
 
-		ret = bch2_sb_validate((*ca)->disk_sb.sb, BCH_VALIDATE_write, &err);
+		ret = bch2_sb_validate((*ca)->disk_sb.sb, 0, BCH_VALIDATE_write, &err);
 		if (ret) {
 			bch2_fs_inconsistent(c, "sb invalid before write: %s", err.buf);
 			goto out;
diff --git a/fs/bcachefs/super-io.h b/fs/bcachefs/super-io.h
index 41562380a353..78f708a6fbcd 100644
--- a/fs/bcachefs/super-io.h
+++ b/fs/bcachefs/super-io.h
@@ -92,7 +92,7 @@ int bch2_sb_from_fs(struct bch_fs *, struct bch_dev *);
 void bch2_free_super(struct bch_sb_handle *);
 int bch2_sb_realloc(struct bch_sb_handle *, unsigned);
 
-int bch2_sb_validate(struct bch_sb *, enum bch_validate_flags, struct printbuf *);
+int bch2_sb_validate(struct bch_sb *, u64, enum bch_validate_flags, struct printbuf *);
 
 int bch2_read_super(const char *, struct bch_opts *, struct bch_sb_handle *);
 int bch2_read_super_silent(const char *, struct bch_opts *, struct bch_sb_handle *);