netfs: Fix gcc-12 warning by embedding vfs inode in netfs_i_context
authorDavid Howells <dhowells@redhat.com>
Thu, 9 Jun 2022 20:46:04 +0000 (21:46 +0100)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 9 Jun 2022 20:55:00 +0000 (13:55 -0700)
commit874c8ca1e60b2c564a48f7e7acc40d328d5c8733
treef56e0d0a842cc459f8a4a062c88dd54a869d82c5
parent3d9f55c57bc3659f986acc421eac431ff6edcc83
netfs: Fix gcc-12 warning by embedding vfs inode in netfs_i_context

While randstruct was satisfied with using an open-coded "void *" offset
cast for the netfs_i_context <-> inode casting, __builtin_object_size() as
used by FORTIFY_SOURCE was not as easily fooled.  This was causing the
following complaint[1] from gcc v12:

  In file included from include/linux/string.h:253,
                   from include/linux/ceph/ceph_debug.h:7,
                   from fs/ceph/inode.c:2:
  In function 'fortify_memset_chk',
      inlined from 'netfs_i_context_init' at include/linux/netfs.h:326:2,
      inlined from 'ceph_alloc_inode' at fs/ceph/inode.c:463:2:
  include/linux/fortify-string.h:242:25: warning: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
    242 |                         __write_overflow_field(p_size_field, size);
        |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix this by embedding a struct inode into struct netfs_i_context (which
should perhaps be renamed to struct netfs_inode).  The struct inode
vfs_inode fields are then removed from the 9p, afs, ceph and cifs inode
structs and vfs_inode is then simply changed to "netfs.inode" in those
filesystems.

Further, rename netfs_i_context to netfs_inode, get rid of the
netfs_inode() function that converted a netfs_i_context pointer to an
inode pointer (that can now be done with &ctx->inode) and rename the
netfs_i_context() function to netfs_inode() (which is now a wrapper
around container_of()).

Most of the changes were done with:

  perl -p -i -e 's/vfs_inode/netfs.inode/'g \
        `git grep -l 'vfs_inode' -- fs/{9p,afs,ceph,cifs}/*.[ch]`

Kees suggested doing it with a pair structure[2] and a special
declarator to insert that into the network filesystem's inode
wrapper[3], but I think it's cleaner to embed it - and then it doesn't
matter if struct randomisation reorders things.

Dave Chinner suggested using a filesystem-specific VFS_I() function in
each filesystem to convert that filesystem's own inode wrapper struct
into the VFS inode struct[4].

Version #2:
 - Fix a couple of missed name changes due to a disabled cifs option.
 - Rename nfs_i_context to nfs_inode
 - Use "netfs" instead of "nic" as the member name in per-fs inode wrapper
   structs.

[ This also undoes commit 507160f46c55 ("netfs: gcc-12: temporarily
  disable '-Wattribute-warning' for now") that is no longer needed ]

Fixes: bc899ee1c898 ("netfs: Add a netfs inode context")
Reported-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
cc: Jonathan Corbet <corbet@lwn.net>
cc: Eric Van Hensbergen <ericvh@gmail.com>
cc: Latchesar Ionkov <lucho@ionkov.net>
cc: Dominique Martinet <asmadeus@codewreck.org>
cc: Christian Schoenebeck <linux_oss@crudebyte.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: Steve French <smfrench@gmail.com>
cc: William Kucharski <william.kucharski@oracle.com>
cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
cc: Dave Chinner <david@fromorbit.com>
cc: linux-doc@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-afs@lists.infradead.org
cc: ceph-devel@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: samba-technical@lists.samba.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-hardening@vger.kernel.org
Link: https://lore.kernel.org/r/d2ad3a3d7bdd794c6efb562d2f2b655fb67756b9.camel@kernel.org/
Link: https://lore.kernel.org/r/20220517210230.864239-1-keescook@chromium.org/
Link: https://lore.kernel.org/r/20220518202212.2322058-1-keescook@chromium.org/
Link: https://lore.kernel.org/r/20220524101205.GI2306852@dread.disaster.area/
Link: https://lore.kernel.org/r/165296786831.3591209.12111293034669289733.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/165305805651.4094995.7763502506786714216.stgit@warthog.procyon.org.uk
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
40 files changed:
Documentation/filesystems/netfs_library.rst
fs/9p/cache.c
fs/9p/v9fs.c
fs/9p/v9fs.h
fs/9p/vfs_addr.c
fs/9p/vfs_inode.c
fs/afs/callback.c
fs/afs/dir.c
fs/afs/dir_edit.c
fs/afs/dir_silly.c
fs/afs/dynroot.c
fs/afs/file.c
fs/afs/fs_operation.c
fs/afs/inode.c
fs/afs/internal.h
fs/afs/super.c
fs/afs/write.c
fs/ceph/addr.c
fs/ceph/cache.c
fs/ceph/cache.h
fs/ceph/caps.c
fs/ceph/file.c
fs/ceph/inode.c
fs/ceph/mds_client.c
fs/ceph/snap.c
fs/ceph/super.c
fs/ceph/super.h
fs/ceph/xattr.c
fs/cifs/cifsfs.c
fs/cifs/cifsglob.h
fs/cifs/file.c
fs/cifs/fscache.c
fs/cifs/fscache.h
fs/cifs/inode.c
fs/cifs/misc.c
fs/cifs/smb2ops.c
fs/netfs/buffered_read.c
fs/netfs/internal.h
fs/netfs/objects.c
include/linux/netfs.h