linux-stable.git/fs, branch v4.4.17

vfs: fix deadlock in file_remove_privs() on overlayfs

2016-08-10T09:49:30+00:00

commit c1892c37769cf89c7e7ba57528ae2ccb5d153c9b upstream.

file_remove_privs() is called with inode lock on file_inode(), which
proceeds to calling notify_change() on file->f_path.dentry.  Which triggers
the WARN_ON_ONCE(!inode_is_locked(inode)) in addition to deadlocking later
when ovl_setattr tries to lock the underlying inode again.

Fix this mess by not mixing the layers, but doing everything on underlying
dentry/inode.

Signed-off-by: Miklos Szeredi 
Fixes: 07a2daab49c5 ("ovl: Copy up underlying inode's ->i_mode to overlay inode")
Signed-off-by: Greg Kroah-Hartman

ovl: handle ATTR_KILL*

2016-08-10T09:49:28+00:00

commit b99c2d913810e56682a538c9f2394d76fca808f8 upstream.

Before 4bacc9c9234c ("overlayfs: Make f_path...") file->f_path pointed to
the underlying file, hence suid/sgid removal on write worked fine.

After that patch file->f_path pointed to the overlay file, and the file
mode bits weren't copied to overlay_inode->i_mode.  So the suid/sgid
removal simply stopped working.

The fix is to copy the mode bits, but then ovl_setattr() needs to clear
ATTR_MODE to avoid the BUG() in notify_change().  So do this first, then in
the next patch copy the mode.

Reported-by: Eryu Guan 
Signed-off-by: Miklos Szeredi 
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Cc: Eric Schultz 
Cc: Eric Hameleers 
[backported by Eric Hameleers as seen in https://bugzilla.kernel.org/show_bug.cgi?id=150711]
Signed-off-by: Greg Kroah-Hartman

namespace: update event counter when umounting a deleted dentry

2016-08-10T09:49:27+00:00

commit e06b933e6ded42384164d28a2060b7f89243b895 upstream.

- m_start() in fs/namespace.c expects that ns->event is incremented each
  time a mount added or removed from ns->list.
- umount_tree() removes items from the list but does not increment event
  counter, expecting that it's done before the function is called.
- There are some codepaths that call umount_tree() without updating
  "event" counter. e.g. from __detach_mounts().
- When this happens m_start may reuse a cached mount structure that no
  longer belongs to ns->list (i.e. use after free which usually leads
  to infinite loop).

This change fixes the above problem by incrementing global event counter
before invoking umount_tree().

Change-Id: I622c8e84dcb9fb63542372c5dbf0178ee86bb589
Signed-off-by: Andrey Ulanov 
Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

9p: use file_dentry()

2016-08-10T09:49:27+00:00

commit b403f0e37a11f84f7ceaf40b0075499e5bcfd220 upstream.

v9fs may be used as lower layer of overlayfs and accessing f_path.dentry
can lead to a crash.  In this case it's a NULL pointer dereference in
p9_fid_create().

Fix by replacing direct access of file->f_path.dentry with the
file_dentry() accessor, which will always return a native object.

Reported-by: Alessio Igor Bogani 
Signed-off-by: Miklos Szeredi 
Tested-by: Alessio Igor Bogani 
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

ext4: verify extent header depth

2016-08-10T09:49:27+00:00

commit 7bc9491645118c9461bd21099c31755ff6783593 upstream.

Although the extent tree depth of 5 should enough be for the worst
case of 2*32 extents of length 1, the extent tree code does not
currently to merge nodes which are less than half-full with a sibling
node, or to shrink the tree depth if possible.  So it's possible, at
least in theory, for the tree depth to be greater than 5.  However,
even in the worst case, a tree depth of 32 is highly unlikely, and if
the file system is maliciously corrupted, an insanely large eh_depth
can cause memory allocation failures that will trigger kernel warnings
(here, eh_depth = 65280):

    JBD2: ext4.exe wants too many credits credits:195849 rsv_credits:0 max:256
    ------------[ cut here ]------------
    WARNING: CPU: 0 PID: 50 at fs/jbd2/transaction.c:293 start_this_handle+0x569/0x580
    CPU: 0 PID: 50 Comm: ext4.exe Not tainted 4.7.0-rc5+ #508
    Stack:
     604a8947 625badd8 0002fd09 00000000
     60078643 00000000 62623910 601bf9bc
     62623970 6002fc84 626239b0 900000125
    Call Trace:
     [<6001c2dc>] show_stack+0xdc/0x1a0
     [<601bf9bc>] dump_stack+0x2a/0x2e
     [<6002fc84>] __warn+0x114/0x140
     [<6002fdff>] warn_slowpath_null+0x1f/0x30
     [<60165829>] start_this_handle+0x569/0x580
     [<60165d4e>] jbd2__journal_start+0x11e/0x220
     [<60146690>] __ext4_journal_start_sb+0x60/0xa0
     [<60120a81>] ext4_truncate+0x131/0x3a0
     [<60123677>] ext4_setattr+0x757/0x840
     [<600d5d0f>] notify_change+0x16f/0x2a0
     [<600b2b16>] do_truncate+0x76/0xc0
     [<600c3e56>] path_openat+0x806/0x1300
     [<600c55c9>] do_filp_open+0x89/0xf0
     [<600b4074>] do_sys_open+0x134/0x1e0
     [<600b4140>] SyS_open+0x20/0x30
     [<6001ea68>] handle_syscall+0x88/0x90
     [<600295fd>] userspace+0x3fd/0x500
     [<6001ac55>] fork_handler+0x85/0x90

    ---[ end trace 08b0b88b6387a244 ]---

[ Commit message modified and the extent tree depath check changed
from 5 to 32 -- tytso ]

Cc: Darrick J. Wong 
Signed-off-by: Vegard Nossum 
Signed-off-by: Theodore Ts'o 
Signed-off-by: Greg Kroah-Hartman

ecryptfs: don't allow mmap when the lower fs doesn't support it

2016-08-10T09:49:27+00:00

commit f0fe970df3838c202ef6c07a4c2b36838ef0a88b upstream.

There are legitimate reasons to disallow mmap on certain files, notably
in sysfs or procfs.  We shouldn't emulate mmap support on file systems
that don't offer support natively.

CVE-2016-1583

Signed-off-by: Jeff Mahoney 
[tyhicks: clean up f_op check by using ecryptfs_file_to_lower()]
Signed-off-by: Tyler Hicks 
Signed-off-by: Greg Kroah-Hartman

Revert "ecryptfs: forbid opening files without mmap handler"

2016-08-10T09:49:27+00:00

commit 78c4e172412de5d0456dc00d2b34050aa0b683b5 upstream.

This reverts commit 2f36db71009304b3f0b95afacd8eba1f9f046b87.

It fixed a local root exploit but also introduced a dependency on
the lower file system implementing an mmap operation just to open a file,
which is a bit of a heavy hammer.  The right fix is to have mmap depend
on the existence of the mmap handler instead.

Signed-off-by: Jeff Mahoney 
Signed-off-by: Tyler Hicks 
Signed-off-by: Greg Kroah-Hartman

locks: use file_inode()

2016-08-10T09:49:27+00:00

commit 6343a2120862f7023006c8091ad95c1f16a32077 upstream.

(Another one for the f_path debacle.)

ltp fcntl33 testcase caused an Oops in selinux_file_send_sigiotask.

The reason is that generic_add_lease() used filp->f_path.dentry->inode
while all the others use file_inode().  This makes a difference for files
opened on overlayfs since the former will point to the overlay inode the
latter to the underlying inode.

So generic_add_lease() added the lease to the overlay inode and
generic_delete_lease() removed it from the underlying inode.  When the file
was released the lease remained on the overlay inode's lock list, resulting
in use after free.

Reported-by: Eryu Guan 
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Signed-off-by: Miklos Szeredi 
Reviewed-by: Jeff Layton 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Greg Kroah-Hartman

fs/nilfs2: fix potential underflow in call to crc32_le

2016-08-10T09:49:25+00:00

commit 63d2f95d63396059200c391ca87161897b99e74a upstream.

The value `bytes' comes from the filesystem which is about to be
mounted.  We cannot trust that the value is always in the range we
expect it to be.

Check its value before using it to calculate the length for the crc32_le
call.  It value must be larger (or equal) sumoff + 4.

This fixes a kernel bug when accidentially mounting an image file which
had the nilfs2 magic value 0x3434 at the right offset 0x406 by chance.
The bytes 0x01 0x00 were stored at 0x408 and were interpreted as a
s_bytes value of 1.  This caused an underflow when substracting sumoff +
4 (20) in the call to crc32_le.

  BUG: unable to handle kernel paging request at ffff88021e600000
  IP:  crc32_le+0x36/0x100
  ...
  Call Trace:
    nilfs_valid_sb.part.5+0x52/0x60 [nilfs2]
    nilfs_load_super_block+0x142/0x300 [nilfs2]
    init_nilfs+0x60/0x390 [nilfs2]
    nilfs_mount+0x302/0x520 [nilfs2]
    mount_fs+0x38/0x160
    vfs_kern_mount+0x67/0x110
    do_mount+0x269/0xe00
    SyS_mount+0x9f/0x100
    entry_SYSCALL_64_fastpath+0x16/0x71

Link: http://lkml.kernel.org/r/1466778587-5184-2-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Torsten Hilbrich 
Tested-by: Torsten Hilbrich 
Signed-off-by: Ryusuke Konishi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

ovl: verify upper dentry before unlink and rename

2016-07-27T16:47:40+00:00

commit 11f3710417d026ea2f4fcf362d866342c5274185 upstream.

Unlink and rename in overlayfs checked the upper dentry for staleness by
verifying upper->d_parent against upperdir.  However the dentry can go
stale also by being unhashed, for example.

Expand the verification to actually look up the name again (under parent
lock) and check if it matches the upper dentry.  This matches what the VFS
does before passing the dentry to filesytem's unlink/rename methods, which
excludes any inconsistency caused by overlayfs.

Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman