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android_kernel_google_msm/fs
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Linus Torvalds a3b4c0bace vfs,proc: guarantee unique inodes in /proc 
commit 51f0885e54 upstream.

Dave Jones found another /proc issue with his Trinity tool: thanks to
the namespace model, we can have multiple /proc dentries that point to
the same inode, aliasing directories in /proc/<pid>/net/ for example.

This ends up being a total disaster, because it acts like hardlinked
directories, and causes locking problems.  We rely on the topological
sort of the inodes pointed to by dentries, and if we have aliased
directories, that odering becomes unreliable.

In short: don't do this.  Multiple dentries with the same (directory)
inode is just a bad idea, and the namespace code should never have
exposed things this way.  But we're kind of stuck with it.

This solves things by just always allocating a new inode during /proc
dentry lookup, instead of using "iget_locked()" to look up existing
inodes by superblock and number.  That actually simplies the code a bit,
at the cost of potentially doing more inode [de]allocations.

That said, the inode lookup wasn't free either (and did a lot of locking
of inodes), so it is probably not that noticeable.  We could easily keep
the old lookup model for non-directory entries, but rather than try to
be excessively clever this just implements the minimal and simplest
workaround for the problem.

Reported-and-tested-by: Dave Jones <davej@redhat.com>
Analyzed-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.2:
 - Adjust context
 - Never drop the pde reference in proc_get_inode(), as callers only
   expect this when we return an existing inode, and we never do that now]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Rui Xiang <rui.xiang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 10:50:30 -08:00
..
9p 9p changes for the 3.4 merge window 2012-03-28 09:58:38 -07:00
adfs switch open-coded instances of d_make_root() to new helper 2012-03-20 21:29:35 -04:00
affs switch open-coded instances of d_make_root() to new helper 2012-03-20 21:29:35 -04:00
afs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-03-21 13:36:41 -07:00
autofs4 autofs - remove autofs dentry mount check 2013-05-11 13:48:06 -07:00
befs switch open-coded instances of d_make_root() to new helper 2012-03-20 21:29:35 -04:00
bfs switch open-coded instances of d_make_root() to new helper 2012-03-20 21:29:35 -04:00
btrfs Btrfs: change how we queue blocks for backref checking 2013-10-13 15:42:50 -07:00
cachefiles switch touch_atime to struct path 2012-03-20 21:29:41 -04:00
ceph ceph: fix statvfs fr_size 2013-06-20 11:58:47 -07:00
cifs cifs: ensure that srv_mutex is held when dealing with ssocket pointer 2013-09-26 17:15:31 -07:00
coda Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
configfs make configfs_pin_fs() return root dentry on success 2012-03-20 21:29:48 -04:00
cramfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-03-21 13:36:41 -07:00
debugfs debugfs: debugfs_remove_recursive() must not rely on list_empty(d_subdirs) 2013-08-14 22:57:07 -07:00
devpts Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-03-21 13:36:41 -07:00
dlm dlm fixes for 3.4 2012-04-23 18:22:42 -07:00
ecryptfs eCryptfs: check for eCryptfs cipher support at mount 2012-11-26 11:37:49 -08:00
efs switch open-coded instances of d_make_root() to new helper 2012-03-20 21:29:35 -04:00
exofs ore: Fix out-of-bounds access in _ios_obj() 2012-08-15 08:10:09 -07:00
exportfs
ext2 migrate ext2_fs.h guts to fs/ext2/ext2.h 2012-03-31 16:03:16 -04:00
ext3 ext3: return 32/64-bit dir name hash according to usage type 2013-11-04 04:23:42 -08:00
ext4 ext4: fix memory leak in xattr 2013-10-22 09:02:25 +01:00
fat fat: fix possible overflow for fat_clusters 2013-06-07 12:49:12 -07:00
freevxfs switch open-coded instances of d_make_root() to new helper 2012-03-20 21:29:35 -04:00
fscache fs/fscache/stats.c: fix memory leak 2013-05-07 19:51:55 -07:00
fuse fuse: invalidate inode attributes on xattr modification 2013-09-26 17:15:52 -07:00
gfs2 GFS2: Test bufdata with buffer locked and gfs2_log_lock held 2013-01-17 08:51:06 -08:00
hfs switch open-coded instances of d_make_root() to new helper 2012-03-20 21:29:35 -04:00
hfsplus hfsplus: fix potential overflow in hfsplus_file_truncate() 2013-04-25 21:19:54 -07:00
hostfs Merge branch 'for-linus-3.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml 2012-03-27 18:29:53 -07:00
hpfs hpfs: better test for errors 2013-07-13 11:03:40 -07:00
hppfs switch open-coded instances of d_make_root() to new helper 2012-03-20 21:29:35 -04:00
hugetlbfs hugetlbfs: fix mmap failure in unaligned size request 2013-05-19 10:54:48 -07:00
isofs isofs: Refuse RW mount of the filesystem instead of making it RO 2013-09-26 17:15:51 -07:00
jbd jbd: Fix lock ordering bug in journal_unmap_buffer() 2012-12-03 11:47:10 -08:00
jbd2 jbd2: fix theoretical race in jbd2__journal_restart 2013-07-21 18:19:00 -07:00
jffs2 jffs2: hold erase_completion_lock on exit 2013-01-17 08:50:46 -08:00
jfs jfs: fix error path in ialloc 2013-11-13 12:01:48 +09:00
lockd lockd: protect nlm_blocked access in nlmsvc_retry_blocked 2013-07-28 16:26:17 -07:00
logfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-03-21 13:36:41 -07:00
minix Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-03-21 13:36:41 -07:00
ncpfs Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
nfs NFSv4: Fix a thinko in nfs4_try_open_cached 2013-06-07 12:49:30 -07:00
nfs_common
nfsd nfsd4: fix decoding of compounds across page boundaries 2013-07-13 11:03:41 -07:00
nilfs2 nilfs2: fix issue with counting number of bio requests for BIO_EOPNOTSUPP error detection 2013-08-29 09:50:13 -07:00
nls
notify fanotify: dont merge permission events 2013-10-01 09:10:52 -07:00
ntfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-03-21 13:36:41 -07:00
ocfs2 ocfs2: fix the end cluster offset of FIEMAP 2013-09-26 17:15:50 -07:00
omfs switch open-coded instances of d_make_root() to new helper 2012-03-20 21:29:35 -04:00
openpromfs switch open-coded instances of d_make_root() to new helper 2012-03-20 21:29:35 -04:00
proc vfs,proc: guarantee unique inodes in /proc 2013-11-29 10:50:30 -08:00
pstore pstore: Avoid deadlock in panic and emergency-restart path 2013-03-04 06:06:43 +08:00
qnx4 qnx4: new helper - try_extent() 2012-03-20 21:29:52 -04:00
qnx6 fs: initial qnx6fs addition 2012-03-20 21:29:38 -04:00
quota Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2012-03-28 10:00:14 -07:00
ramfs fs: ramfs: file-nommu: add SetPageUptodate() 2012-07-16 09:04:45 -07:00
reiserfs reiserfs: Fix warning and inode leak when deleting inode with xattrs 2013-04-12 09:38:43 -07:00
romfs MTD merge for 3.4 2012-03-30 17:31:56 -07:00
squashfs Add an extra mount time sanity check, plus some code cleanups and bug fixes. 2012-03-28 18:05:54 -07:00
sysfs sysfs: fix use after free in case of concurrent read/write and readdir 2013-05-07 19:51:54 -07:00
sysv switch open-coded instances of d_make_root() to new helper 2012-03-20 21:29:35 -04:00
ubifs UBIFS: fix a horrid bug 2013-07-03 10:59:05 -07:00
udf udf: avoid info leak on export 2013-03-28 12:12:27 -07:00
ufs Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
xfs xfs: kill suid/sgid through the truncate path. 2013-06-07 12:49:30 -07:00
aio.c aio: fix possible invalid memory access when DEBUG is enabled 2013-05-01 09:41:03 -07:00
anon_inodes.c anon_inodes: move allocation of anon_inode into ->mount() 2012-03-20 21:29:45 -04:00
attr.c vfs: increment iversion when a file is truncated 2012-06-10 00:36:12 +09:00
bad_inode.c
binfmt_aout.c VM: add "vm_mmap()" helper function 2012-04-20 17:29:13 -07:00
binfmt_elf.c coredump: prevent double-free on an error path in core dumper 2012-10-07 08:32:27 -07:00
binfmt_elf_fdpic.c VM: add "vm_mmap()" helper function 2012-04-20 17:29:13 -07:00
binfmt_em86.c exec: use -ELOOP for max recursion depth 2013-03-28 12:12:28 -07:00
binfmt_flat.c VM: add "vm_mmap()" helper function 2012-04-20 17:29:13 -07:00
binfmt_misc.c exec: use -ELOOP for max recursion depth 2013-03-28 12:12:28 -07:00
binfmt_script.c exec: use -ELOOP for max recursion depth 2013-03-28 12:12:28 -07:00
binfmt_som.c VM: add "vm_mmap()" helper function 2012-04-20 17:29:13 -07:00
bio-integrity.c fs: remove the second argument of k[un]map_atomic() 2012-03-20 21:48:21 +08:00
bio.c SCSI: sg: Fix user memory corruption when SG_IO is interrupted by a signal 2013-09-07 21:58:16 -07:00
block_dev.c writeback: Fix periodic writeback after fs mount 2013-07-28 16:26:08 -07:00
buffer.c block: replace __getblk_slow misfix by grow_dev_page fix 2012-09-14 10:00:20 -07:00
char_dev.c
compat.c Fix: compat_rw_copy_check_uvector() misuse in aio, readv, writev, and security keys 2013-03-14 11:29:51 -07:00
compat_binfmt_elf.c
compat_ioctl.c fs/compat_ioctl.c: VIDEO_SET_SPU_PALETTE missing error check 2012-10-31 10:02:55 -07:00
dcache.c vfs: d_obtain_alias() needs to use "/" as default name. 2013-08-14 22:57:08 -07:00
dcookies.c
direct-io.c fs: Fix possible use-after-free with AIO 2013-03-04 06:06:41 +08:00
drop_caches.c
eventfd.c
eventpoll.c epoll: prevent missed events on EPOLL_CTL_MOD 2013-01-17 08:50:54 -08:00
exec.c perf: Disable monitoring on setuid processes for regular users 2013-07-03 10:59:04 -07:00
fcntl.c
fhandle.c
fifo.c fifo: Do not restart open() if it already found a partner 2012-07-19 08:58:56 -07:00
file.c Merge branch 'x86-x32-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 18:12:23 -07:00
file_table.c vfs: drop_file_write_access() made static 2012-03-20 21:29:32 -04:00
filesystems.c
fs-writeback.c ext4: fix potential deadlock in ext4_nonda_switch() 2012-10-13 05:38:49 +09:00
fs_struct.c The following text was taken from the original review request: 2012-03-24 10:24:31 -07:00
generic_acl.c
inode.c vfs: Revert spurious fix to spinning prevention in prune_icache_sb 2013-04-16 21:27:26 -07:00
internal.h
ioctl.c
ioprio.c
Kconfig Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-03-21 13:36:41 -07:00
Kconfig.binfmt
libfs.c dentry leak in simple_fill_super() failure exit 2012-04-09 01:39:22 -04:00
locks.c locks: fix checking of fcntl_setlease argument 2012-08-09 08:31:29 -07:00
Makefile fs: initial qnx6fs addition 2012-03-20 21:29:38 -04:00
mbcache.c
mount.h
mpage.c
namei.c vfs: make word-at-a-time accesses handle a non-existing page 2012-05-03 14:01:40 -07:00
namespace.c vfs: umount_tree() might be called on subtree that had never made it 2012-06-10 00:36:12 +09:00
no-block.c
open.c vfs: canonicalize create mode in build_open_flags() 2012-09-14 10:00:05 -07:00
pipe.c vfs: fix pipe counter breakage 2013-03-14 11:29:51 -07:00
pnode.c
pnode.h
posix_acl.c
proc_namespace.c
read_write.c
read_write.h
readdir.c
select.c posix_types.h: Cleanup stale __NFDBITS and related definitions 2012-08-09 08:31:39 -07:00
seq_file.c The following text was taken from the original review request: 2012-03-24 10:24:31 -07:00
signalfd.c
splice.c tcp: fix MSG_SENDPAGE_NOTLAST logic 2013-01-11 09:07:14 -08:00
stack.c
stat.c vfs: make O_PATH file descriptors usable for 'fstat()' 2012-10-02 10:29:51 -07:00
statfs.c vfs: allow O_PATH file descriptors for fstatfs() 2013-10-22 09:02:25 +01:00
super.c livelock avoidance in sget() 2013-08-04 16:25:59 +08:00
sync.c
timerfd.c
utimes.c
xattr.c fs/xattr.c:setxattr(): improve handling of allocation failures 2012-04-05 15:25:50 -07:00
xattr_acl.c