linux-stable.git/fs, branch linux-4.18.y

gfs2: Fix metadata read-ahead during truncate (2)

2018-11-21T08:22:10+00:00

commit e7445ceddfc220c1aede6d42758a5acb8844e9c3 upstream.

The previous attempt to fix for metadata read-ahead during truncate was
incorrect: for files with a height > 2 (1006989312 bytes with a block
size of 4096 bytes), read-ahead requests were not being issued for some
of the indirect blocks discovered while walking the metadata tree,
leading to significant slow-downs when deleting large files.  Fix that.

In addition, only issue read-ahead requests in the first pass through
the meta-data tree, while deallocating data blocks.

Fixes: c3ce5aa9b0 ("gfs2: Fix metadata read-ahead during truncate")
Cc: stable@vger.kernel.org # v4.16+
Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Greg Kroah-Hartman

gfs2: Put bitmap buffers in put_super

2018-11-21T08:22:10+00:00

commit 10283ea525d30f2e99828978fd04d8427876a7ad upstream.

gfs2_put_super calls gfs2_clear_rgrpd to destroy the gfs2_rgrpd objects
attached to the resource group glocks.  That function should release the
buffers attached to the gfs2_bitmap objects (bi_bh), but the call to
gfs2_rgrp_brelse for doing that is missing.

When gfs2_releasepage later runs across these buffers which are still
referenced, it refuses to free them.  This causes the pages the buffers
are attached to to remain referenced as well.  With enough mount/unmount
cycles, the system will eventually run out of memory.

Fix this by adding the missing call to gfs2_rgrp_brelse in
gfs2_clear_rgrpd.

(Also fix a gfs2_rgrp_relse -> gfs2_rgrp_brelse typo in a comment.)

Fixes: 39b0f1e92908 ("GFS2: Don't brelse rgrp buffer_heads every allocation")
Cc: stable@vger.kernel.org # v4.2+
Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Greg Kroah-Hartman

configfs: replace strncpy with memcpy

2018-11-21T08:22:10+00:00

commit 1823342a1f2b47a4e6f5667f67cd28ab6bc4d6cd upstream.

gcc 8.1.0 complains:

fs/configfs/symlink.c:67:3: warning:
	'strncpy' output truncated before terminating nul copying as many
	bytes from a string as its length
fs/configfs/symlink.c: In function 'configfs_get_link':
fs/configfs/symlink.c:63:13: note: length computed here

Using strncpy() is indeed less than perfect since the length of data to
be copied has already been determined with strlen(). Replace strncpy()
with memcpy() to address the warning and optimize the code a little.

Signed-off-by: Guenter Roeck 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Nobuhiro Iwamatsu 
Signed-off-by: Greg Kroah-Hartman

fuse: fix leaked notify reply

2018-11-21T08:22:10+00:00

commit 7fabaf303458fcabb694999d6fa772cc13d4e217 upstream.

fuse_request_send_notify_reply() may fail if the connection was reset for
some reason (e.g. fs was unmounted).  Don't leak request reference in this
case.  Besides leaking memory, this resulted in fc->num_waiting not being
decremented and hence fuse_wait_aborted() left in a hanging and unkillable
state.

Fixes: 2d45ba381a74 ("fuse: add retrieve request")
Fixes: b8f95e5d13f5 ("fuse: umount should wait for all requests")
Reported-and-tested-by: syzbot+6339eda9cb4ebbc4c37b@syzkaller.appspotmail.com
Signed-off-by: Miklos Szeredi 
Cc:  #v2.6.36
Signed-off-by: Greg Kroah-Hartman

fuse: fix use-after-free in fuse_direct_IO()

2018-11-21T08:22:10+00:00

commit ebacb81273599555a7a19f7754a1451206a5fc4f upstream.

In async IO blocking case the additional reference to the io is taken for
it to survive fuse_aio_complete(). In non blocking case this additional
reference is not needed, however we still reference io to figure out
whether to wait for completion or not. This is wrong and will lead to
use-after-free. Fix it by storing blocking information in separate
variable.

This was spotted by KASAN when running generic/208 fstest.

Signed-off-by: Lukas Czerner 
Reported-by: Zorro Lang 
Signed-off-by: Miklos Szeredi 
Fixes: 744742d692e3 ("fuse: Add reference counting for fuse_io_priv")
Cc:  # v4.6
Signed-off-by: Greg Kroah-Hartman

nfsd: COPY and CLONE operations require the saved filehandle to be set

2018-11-21T08:22:09+00:00

commit 01310bb7c9c98752cc763b36532fab028e0f8f81 upstream.

Make sure we have a saved filehandle, otherwise we'll oops with a null
pointer dereference in nfs4_preprocess_stateid_op().

Signed-off-by: Scott Mayhew 
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields 
Signed-off-by: Greg Kroah-Hartman

NFSv4: Don't exit the state manager without clearing NFS4CLNT_MANAGER_RUNNING

2018-11-21T08:22:09+00:00

commit 21a446cf186570168b7281b154b1993968598aca upstream.

If we exit the NFSv4 state manager due to a umount, then we can end up
leaving the NFS4CLNT_MANAGER_RUNNING flag set. If another mount causes
the nfs4_client to be rereferenced before it is destroyed, then we end
up never being able to recover state.

Fixes: 47c2199b6eb5 ("NFSv4.1: Ensure state manager thread dies on last ...")
Signed-off-by: Trond Myklebust 
Cc: stable@vger.kernel.org # v4.15+
Signed-off-by: Greg Kroah-Hartman

mnt: fix __detach_mounts infinite loop

2018-11-21T08:22:09+00:00

commit 1e9c75fb9c47a75a9aec0cd17db5f6dc36b58e00 upstream.

Since commit ff17fa561a04 ("d_invalidate(): unhash immediately")
immediately unhashes the dentry, we'll never return the mountpoint in
lookup_mountpoint(), which can lead to an unbreakable loop in
d_invalidate().

I have reports of NFS clients getting into this condition after the server
removes an export of an existing mount created through follow_automount(),
but I suspect there are various other ways to produce this problem if we
hunt down users of d_invalidate().  For example, it is possible to get into
this state by using XFS' d_invalidate() call in xfs_vn_unlink():

truncate -s 100m img{1,2}

mkfs.xfs -q -n version=ci img1
mkfs.xfs -q -n version=ci img2

mkdir -p /mnt/xfs
mount img1 /mnt/xfs

mkdir /mnt/xfs/sub1
mount img2 /mnt/xfs/sub1

cat > /mnt/xfs/sub1/foo &
umount -l /mnt/xfs/sub1
mount img2 /mnt/xfs/sub1

mount --make-private /mnt/xfs

mkdir /mnt/xfs/sub2
mount --move /mnt/xfs/sub1 /mnt/xfs/sub2
rmdir /mnt/xfs/sub1

Fix this by moving the check for an unlinked dentry out of the
detach_mounts() path.

Fixes: ff17fa561a04 ("d_invalidate(): unhash immediately")
Cc: stable@vger.kernel.org
Reviewed-by: "Eric W. Biederman" 
Signed-off-by: Benjamin Coddington 
Signed-off-by: Eric W. Biederman 
Signed-off-by: Greg Kroah-Hartman

mount: Prevent MNT_DETACH from disconnecting locked mounts

2018-11-21T08:22:09+00:00

commit 9c8e0a1b683525464a2abe9fb4b54404a50ed2b4 upstream.

Timothy Baldwin  wrote:
> As per mount_namespaces(7) unprivileged users should not be able to look under mount points:
>
>   Mounts that come as a single unit from more privileged mount are locked
>   together and may not be separated in a less privileged mount namespace.
>
> However they can:
>
> 1. Create a mount namespace.
> 2. In the mount namespace open a file descriptor to the parent of a mount point.
> 3. Destroy the mount namespace.
> 4. Use the file descriptor to look under the mount point.
>
> I have reproduced this with Linux 4.16.18 and Linux 4.18-rc8.
>
> The setup:
>
> $ sudo sysctl kernel.unprivileged_userns_clone=1
> kernel.unprivileged_userns_clone = 1
> $ mkdir -p A/B/Secret
> $ sudo mount -t tmpfs hide A/B
>
>
> "Secret" is indeed hidden as expected:
>
> $ ls -lR A
> A:
> total 0
> drwxrwxrwt 2 root root 40 Feb 12 21:08 B
>
> A/B:
> total 0
>
>
> The attack revealing "Secret":
>
> $ unshare -Umr sh -c "exec unshare -m ls -lR /proc/self/fd/4/ 4 /proc/self/fd/4/:
> total 0
> drwxr-xr-x 3 root root 60 Feb 12 21:08 B
>
> /proc/self/fd/4/B:
> total 0
> drwxr-xr-x 2 root root 40 Feb 12 21:08 Secret
>
> /proc/self/fd/4/B/Secret:
> total 0

I tracked this down to put_mnt_ns running passing UMOUNT_SYNC and
disconnecting all of the mounts in a mount namespace.  Fix this by
factoring drop_mounts out of drop_collected_mounts and passing
0 instead of UMOUNT_SYNC.

There are two possible behavior differences that result from this.
- No longer setting UMOUNT_SYNC will no longer set MNT_SYNC_UMOUNT on
  the vfsmounts being unmounted.  This effects the lazy rcu walk by
  kicking the walk out of rcu mode and forcing it to be a non-lazy
  walk.
- No longer disconnecting locked mounts will keep some mounts around
  longer as they stay because the are locked to other mounts.

There are only two users of drop_collected mounts: audit_tree.c and
put_mnt_ns.

In audit_tree.c the mounts are private and there are no rcu lazy walks
only calls to iterate_mounts. So the changes should have no effect
except for a small timing effect as the connected mounts are disconnected.

In put_mnt_ns there may be references from process outside the mount
namespace to the mounts.  So the mounts remaining connected will
be the bug fix that is needed.  That rcu walks are allowed to continue
appears not to be a problem especially as the rcu walk change was about
an implementation detail not about semantics.

Cc: stable@vger.kernel.org
Fixes: 5ff9d8a65ce8 ("vfs: Lock in place mounts from more privileged users")
Reported-by: Timothy Baldwin 
Tested-by: Timothy Baldwin 
Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Greg Kroah-Hartman

mount: Don't allow copying MNT_UNBINDABLE|MNT_LOCKED mounts

2018-11-21T08:22:09+00:00

commit df7342b240185d58d3d9665c0bbf0a0f5570ec29 upstream.

Jonathan Calmels from NVIDIA reported that he's able to bypass the
mount visibility security check in place in the Linux kernel by using
a combination of the unbindable property along with the private mount
propagation option to allow a unprivileged user to see a path which
was purposefully hidden by the root user.

Reproducer:
  # Hide a path to all users using a tmpfs
  root@castiana:~# mount -t tmpfs tmpfs /sys/devices/
  root@castiana:~#

  # As an unprivileged user, unshare user namespace and mount namespace
  stgraber@castiana:~$ unshare -U -m -r

  # Confirm the path is still not accessible
  root@castiana:~# ls /sys/devices/

  # Make /sys recursively unbindable and private
  root@castiana:~# mount --make-runbindable /sys
  root@castiana:~# mount --make-private /sys

  # Recursively bind-mount the rest of /sys over to /mnnt
  root@castiana:~# mount --rbind /sys/ /mnt

  # Access our hidden /sys/device as an unprivileged user
  root@castiana:~# ls /mnt/devices/
  breakpoint cpu cstate_core cstate_pkg i915 intel_pt isa kprobe
  LNXSYSTM:00 msr pci0000:00 platform pnp0 power software system
  tracepoint uncore_arb uncore_cbox_0 uncore_cbox_1 uprobe virtual

Solve this by teaching copy_tree to fail if a mount turns out to be
both unbindable and locked.

Cc: stable@vger.kernel.org
Fixes: 5ff9d8a65ce8 ("vfs: Lock in place mounts from more privileged users")
Reported-by: Jonathan Calmels 
Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Greg Kroah-Hartman