[PATCH v10 2/3] block: change annotation of rdb_CylBlocks in affs_hardblocks.h

[Michael Schmitz <schmitzmic@gmail.com>]

The Amiga partition parser module uses signed int for partition sector
address and count, which will overflow for disks larger than 1 TB.

Use u64 as type for sector address and size to allow using disks up to
2 TB without LBD support, and disks larger than 2 TB with LBD. The RBD
format allows to specify disk sizes up to 2^128 bytes (though native
OS limitations reduce this somewhat, to max 2^68 bytes), so check for
u64 overflow carefully to protect against overflowing sector_t.

This bug was reported originally in 2012, and the fix was created by
the RDB author, Joanne Dow <jdow@earthlink.net>. A patch had been
discussed and reviewed on linux-m68k at that time but never officially
submitted (now resubmitted as patch 1 of this series).

Patch 3 (this series) adds additional error checking and warning
messages. One of the error checks now makes use of the previously
unused rdb_CylBlocks field, which causes a 'sparse' warning
(cast to restricted __be32).

Annotate rdb_CylBlocks field as big endian to shut up the warning.
Add comment to document that the same annotation is going to be
needed for any other fields that may be used by the kernel in
future.

Reported-by: Martin Steigerwald <Martin@lichtvoll.de>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=43511
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Message-ID: <201206192146.09327.Martin@lichtvoll.de>
Cc: <stable@vger.kernel.org> # 5.2
Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>
---
 include/uapi/linux/affs_hardblocks.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/affs_hardblocks.h b/include/uapi/linux/affs_hardblocks.h
index 5e2fb8481252..9da5bc607939 100644
--- a/include/uapi/linux/affs_hardblocks.h
+++ b/include/uapi/linux/affs_hardblocks.h
@@ -6,6 +6,11 @@
 
 /* Just the needed definitions for the RDB of an Amiga HD. */
 
+/* MSch 20230615: any field used by the Linux kernel must be
+ * annotated __be32! If any fields require increase to 64
+ * bit size, rdb_ID _must_ be changed!
+ */
+
 struct RigidDiskBlock {
 	__u32	rdb_ID;
 	__be32	rdb_SummedLongs;
@@ -32,7 +37,7 @@ struct RigidDiskBlock {
 	__u32	rdb_RDBBlocksHi;
 	__u32	rdb_LoCylinder;
 	__u32	rdb_HiCylinder;
-	__u32	rdb_CylBlocks;
+	__be32	rdb_CylBlocks;
 	__u32	rdb_AutoParkSeconds;
 	__u32	rdb_HighRDSKBlock;
 	__u32	rdb_Reserved4;
-- 
2.17.1