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Ian Kent a32744d4ab autofs: work around unhappy compat problem on x86-64 
When the autofs protocol version 5 packet type was added in commit
5c0a32fc2c ("autofs4: add new packet type for v5 communications"), it
obvously tried quite hard to be word-size agnostic, and uses explicitly
sized fields that are all correctly aligned.

However, with the final "char name[NAME_MAX+1]" array at the end, the
actual size of the structure ends up being not very well defined:
because the struct isn't marked 'packed', doing a "sizeof()" on it will
align the size of the struct up to the biggest alignment of the members
it has.

And despite all the members being the same, the alignment of them is
different: a "__u64" has 4-byte alignment on x86-32, but native 8-byte
alignment on x86-64.  And while 'NAME_MAX+1' ends up being a nice round
number (256), the name[] array starts out a 4-byte aligned.

End result: the "packed" size of the structure is 300 bytes: 4-byte, but
not 8-byte aligned.

As a result, despite all the fields being in the same place on all
architectures, sizeof() will round up that size to 304 bytes on
architectures that have 8-byte alignment for u64.

Note that this is *not* a problem for 32-bit compat mode on POWER, since
there __u64 is 8-byte aligned even in 32-bit mode.  But on x86, 32-bit
and 64-bit alignment is different for 64-bit entities, and as a result
the structure that has exactly the same layout has different sizes.

So on x86-64, but no other architecture, we will just subtract 4 from
the size of the structure when running in a compat task.  That way we
will write the properly sized packet that user mode expects.

Not pretty.  Sadly, this very subtle, and unnecessary, size difference
has been encoded in user space that wants to read packets of *exactly*
the right size, and will refuse to touch anything else.

Reported-and-tested-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2012-02-25 12:10:27 -08:00
..
9p Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs 2012-01-10 15:09:01 -08:00
adfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
affs affs: propagate umode_t 2012-01-03 22:55:04 -05:00
afs switch ->create() to umode_t 2012-01-03 22:54:53 -05:00
autofs4 autofs: work around unhappy compat problem on x86-64 2012-02-25 12:10:27 -08:00
befs vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
bfs switch ->create() to umode_t 2012-01-03 22:54:53 -05:00
btrfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2012-02-24 09:02:53 -08:00
cachefiles fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
ceph Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client 2012-02-02 15:47:33 -08:00
cifs cifs: don't return error from standard_receive3 after marking response malformed 2012-02-07 22:25:31 -06:00
coda coda: switch coda_cnode_make() to sane API as well, clean coda_lookup() 2012-01-10 11:13:16 -05:00
configfs configfs: convert to umode_t 2012-01-03 22:54:57 -05:00
cramfs Merge branches 'vfsmount-guts', 'umode_t' and 'partitions' into Z 2012-01-06 23:15:54 -05:00
debugfs kernel-doc: fix new warnings in debugfs 2012-01-24 10:47:41 -08:00
devpts devpts: fix double-free on mount failure 2012-01-08 20:19:03 -05:00
dlm Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm 2012-01-10 14:55:55 -08:00
ecryptfs ecryptfs: remove the second argument of k[un]map_atomic() 2012-02-16 16:06:27 -06:00
efs vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
exofs Merge branch 'for-linus' of git://git.open-osd.org/linux-open-osd 2012-01-09 12:51:01 -08:00
exportfs
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ext2 ext2: protect inode changes in the SETVERSION and SETFLAGS ioctls 2012-01-11 13:39:02 +01:00
ext3 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2012-01-09 12:51:21 -08:00
ext4 Merge branch 'for_linus' into for_linus_merged 2012-01-10 11:54:07 -05:00
fat Merge branch 'usb-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb 2012-01-09 12:09:47 -08:00
freevxfs fs: propagate umode_t, misc bits 2012-01-03 22:55:10 -05:00
fscache FS-Cache: Fix __fscache_uncache_all_inode_pages()'s outer loop 2011-07-21 10:59:16 -07:00
fuse Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse 2012-01-12 12:39:21 -08:00
gfs2 GFS2: Fix nlink setting on inode creation 2012-01-11 12:35:05 +00:00
hfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
hfsplus hfsplus: creation of hidden dir on mount can fail 2012-01-10 17:48:52 -05:00
hostfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
hpfs switch ->mknod() to umode_t 2012-01-03 22:54:54 -05:00
hppfs vfs: for usbfs, etc. internal vfsmounts ->mnt_sb->s_root == ->mnt_root 2012-01-03 22:52:41 -05:00
hugetlbfs mm: compaction: introduce sync-light migration for use by compaction 2012-01-12 20:13:09 -08:00
isofs isofs: inode leak on mount failure 2012-01-09 10:48:11 -05:00
jbd jbd: Issue cache flush after checkpointing 2012-01-11 13:36:57 +01:00
jbd2 Merge branch 'for_linus' into for_linus_merged 2012-01-10 11:54:07 -05:00
jffs2 jffs2: do not initialize variable unnecessarily 2012-01-11 09:53:51 +00:00
jfs Merge branch 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm 2012-01-08 13:10:57 -08:00
lockd module_param: make bool parameters really bool (drivers & misc) 2012-01-13 09:32:20 +10:30
logfs mtd: fix merge conflict resolution breakage 2012-02-01 11:10:24 -08:00
minix Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-01-08 12:19:57 -08:00
ncpfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
nfs NFSv4: fix server_scope memory leak 2012-02-17 17:34:03 -05:00
nfs_common
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nfsd Merge branch 'for-3.3' of git://linux-nfs.org/~bfields/linux 2012-01-14 12:26:41 -08:00
nilfs2 nilfs2: avoid overflowing segment numbers in nilfs_ioctl_clean_segments() 2012-02-08 19:03:51 -08:00
nls NLS: raname "maxlen" to "maxout" in UTF conversion routines 2011-11-26 19:58:47 -08:00
notify fsnotify: don't BUG in fsnotify_destroy_mark() 2012-01-14 18:01:42 -08:00
ntfs module_param: avoid bool abuse, add bint for special cases. 2012-01-13 09:32:17 +10:30
ocfs2 ocfs2: deal with wraparounds of i_nlink in ocfs2_rename() 2012-02-13 20:45:39 -05:00
omfs omfs: propagate umode_t 2012-01-03 22:55:01 -05:00
openpromfs vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
proc Fix race in process_vm_rw_core 2012-02-02 12:55:17 -08:00
pstore pstore: gracefully handle NULL pstore_info functions 2011-11-18 13:49:00 -08:00
qnx4 qnx4: don't leak ->BitMap on late failure exits 2012-01-19 13:54:36 -05:00
quota quota: Fix deadlock with suspend and quotas 2012-02-13 20:45:39 -05:00
ramfs pohmelfs: propagate umode_t 2012-01-03 22:55:07 -05:00
reiserfs reiserfs: don't lock root inode searching 2012-01-10 16:30:54 -08:00
romfs MTD pull for 3.3 2012-01-10 13:45:22 -08:00
squashfs Merge git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-next 2012-01-13 10:34:57 -08:00
sysfs sysfs: Complain bitterly about attempts to remove files from nonexistent directories. 2012-01-24 12:12:32 -08:00
sysv vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
ubifs UBIFS: fix non-debug configuration build 2012-01-15 13:46:02 +02:00
udf Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2012-01-09 12:51:21 -08:00
ufs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
xfs xfs: make inode quota check more general 2012-02-21 10:12:43 -06:00
Kconfig Merge branch 'for-linus' of git://git.open-osd.org/linux-open-osd 2012-01-09 12:51:01 -08:00
Kconfig.binfmt fs: binfmt_elf: create Kconfig variable for PIE randomization 2012-01-10 16:30:51 -08:00
Makefile Merge branches 'vfsmount-guts', 'umode_t' and 'partitions' into Z 2012-01-06 23:15:54 -05:00
aio.c Unused iocbs in a batch should not be accounted as active. 2012-01-13 20:39:44 -08:00
anon_inodes.c vfs: dont chain pipe/anon/socket on superblock s_inodes list 2011-07-26 12:57:09 -04:00
attr.c switch is_sxid() to umode_t 2012-01-03 22:55:11 -05:00
bad_inode.c switch ->mknod() to umode_t 2012-01-03 22:54:54 -05:00
binfmt_aout.c
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binfmt_elf.c fs: binfmt_elf: create Kconfig variable for PIE randomization 2012-01-10 16:30:51 -08:00
binfmt_elf_fdpic.c consolidate BINPRM_FLAGS_ENFORCE_NONDUMP handling 2011-07-20 01:43:10 -04:00
binfmt_em86.c
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binfmt_flat.c
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binfmt_misc.c vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
binfmt_script.c
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binfmt_som.c
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bio-integrity.c fs: add export.h to files using EXPORT_SYMBOL/THIS_MODULE macros 2011-10-31 19:30:31 -04:00
bio.c bio: don't overflow in bio_get_nr_vecs() 2012-02-08 22:07:18 +01:00
block_dev.c vfs: cache request_queue in struct block_device 2012-01-12 20:13:12 -08:00
buffer.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
char_dev.c char_dev.c: fix up some whitespace errors 2011-12-13 11:18:17 -08:00
compat.c vfs: fix compat_sys_stat() handling of overflows in st_nlink 2012-02-13 20:45:39 -05:00
compat_binfmt_elf.c
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compat_ioctl.c Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media 2012-01-15 12:49:56 -08:00
dcache.c vfs: fix panic in __d_lookup() with high dentry hashtable counts 2012-02-13 20:45:38 -05:00
dcookies.c
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direct-io.c Restore direct_io / truncate locking API 2012-02-23 15:56:21 -08:00
drop_caches.c
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eventfd.c
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eventpoll.c epoll: ep_unregister_pollwait() can use the freed pwq->whead 2012-02-24 11:42:50 -08:00
exec.c exec: fix use-after-free bug in setup_new_exec() 2012-02-06 15:15:20 -08:00
fcntl.c
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fhandle.c vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
fifo.c
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file.c
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file_table.c vfs: prevent remount read-only if pending removes 2012-01-06 23:20:13 -05:00
filesystems.c vfs: convert fs_supers to hlist 2012-01-03 22:52:39 -05:00
fs-writeback.c writeback: fix NULL bdi->dev in trace writeback_single_inode 2012-02-01 16:53:40 +08:00
fs_struct.c
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generic_acl.c switch posix_acl_equiv_mode() to umode_t * 2011-08-01 02:10:06 -04:00
inode.c vfs: fix panic in __d_lookup() with high dentry hashtable counts 2012-02-13 20:45:38 -05:00
internal.h vfs: protect remounting superblock read-only 2012-01-06 23:20:12 -05:00
ioctl.c vfs: fix up ENOIOCTLCMD error handling 2012-01-05 15:40:12 -08:00
ioprio.c block: strip out locking optimization in put_io_context() 2012-02-07 07:51:30 +01:00
libfs.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
locks.c vfs: fix handling of lock allocation failure in lease-break case 2011-12-26 10:25:26 -08:00
mbcache.c
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mount.h vfs: keep list of mounts for each superblock 2012-01-06 23:20:12 -05:00
mpage.c fs: remove unneeded plug in mpage_readpages() 2012-01-12 09:19:54 +01:00
namei.c vfs: fix d_inode_lookup() dentry ref leak 2012-02-13 20:45:37 -05:00
namespace.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-01-08 13:21:22 -08:00
no-block.c
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open.c switch security_path_chmod() to struct path * 2012-01-06 23:16:53 -05:00
pipe.c pipe: fail cleanly when root tries F_SETPIPE_SZ with big size 2012-01-12 20:13:04 -08:00
pnode.c vfs: switch pnode.h macros to struct mount * 2012-01-03 22:57:11 -05:00
pnode.h vfs: switch pnode.h macros to struct mount * 2012-01-03 22:57:11 -05:00
posix_acl.c vfs: pass all mask flags check_acl and posix_acl_permission 2011-10-28 14:58:54 +02:00
proc_namespace.c vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
read_write.c Cross Memory Attach 2011-10-31 17:30:44 -07:00
read_write.h
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readdir.c
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select.c sys_poll: fix incorrect type for 'timeout' parameter 2012-02-21 17:24:20 -08:00
seq_file.c constify seq_file stuff 2012-01-03 22:52:40 -05:00
signalfd.c epoll: ep_unregister_pollwait() can use the freed pwq->whead 2012-02-24 11:42:50 -08:00
splice.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
stack.c filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
stat.c readlinkat: ensure we return ENOENT for the empty pathname for normal lookups 2011-11-02 12:53:42 +01:00
statfs.c vfs: new helper - vfs_ustat() 2012-01-03 22:53:07 -05:00
super.c vfs: Provide function to get superblock and wait for it to thaw 2012-02-13 20:45:38 -05:00
sync.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
timerfd.c
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utimes.c
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xattr.c vfs: mnt_drop_write_file() 2012-01-03 22:52:40 -05:00
xattr_acl.c
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