linux-stable.git/fs, branch v4.4.201

cgroup,writeback: don't switch wbs immediately on dead wbs if the memcg is dead

2019-11-12T18:13:31+00:00

commit 65de03e251382306a4575b1779c57c87889eee49 upstream.

cgroup writeback tries to refresh the associated wb immediately if the
current wb is dead.  This is to avoid keeping issuing IOs on the stale
wb after memcg - blkcg association has changed (ie. when blkcg got
disabled / enabled higher up in the hierarchy).

Unfortunately, the logic gets triggered spuriously on inodes which are
associated with dead cgroups.  When the logic is triggered on dead
cgroups, the attempt fails only after doing quite a bit of work
allocating and initializing a new wb.

While c3aab9a0bd91 ("mm/filemap.c: don't initiate writeback if mapping
has no dirty pages") alleviated the issue significantly as it now only
triggers when the inode has dirty pages.  However, the condition can
still be triggered before the inode is switched to a different cgroup
and the logic simply doesn't make sense.

Skip the immediate switching if the associated memcg is dying.

This is a simplified version of the following two patches:

 * https://lore.kernel.org/linux-mm/20190513183053.GA73423@dennisz-mbp/
 * http://lkml.kernel.org/r/156355839560.2063.5265687291430814589.stgit@buzz

Cc: Konstantin Khlebnikov 
Fixes: e8a7abf5a5bd ("writeback: disassociate inodes from dying bdi_writebacks")
Acked-by: Dennis Zhou 
Signed-off-by: Tejun Heo 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

NFSv4: Don't allow a cached open with a revoked delegation

2019-11-12T18:13:29+00:00

[ Upstream commit be3df3dd4c70ee020587a943a31b98a0fb4b6424 ]

If the delegation is marked as being revoked, we must not use it
for cached opens.

Fixes: 869f9dfa4d6d ("NFSv4: Fix races between nfs_remove_bad_delegation() and delegation return")
Signed-off-by: Trond Myklebust 
Signed-off-by: Anna Schumaker 
Signed-off-by: Sasha Levin

configfs: fix a deadlock in configfs_symlink()

2019-11-12T18:13:24+00:00

commit 351e5d869e5ac10cb40c78b5f2d7dfc816ad4587 upstream.

Configfs abuses symlink(2).  Unlike the normal filesystems, it
wants the target resolved at symlink(2) time, like link(2) would've
done.  The problem is that ->symlink() is called with the parent
directory locked exclusive, so resolving the target inside the
->symlink() is easily deadlocked.

Short of really ugly games in sys_symlink() itself, all we can
do is to unlock the parent before resolving the target and
relock it after.  However, that invalidates the checks done
by the caller of ->symlink(), so we have to
	* check that dentry is still where it used to be
(it couldn't have been moved, but it could've been unhashed)
	* recheck that it's still negative (somebody else
might've successfully created a symlink with the same name
while we were looking the target up)
	* recheck the permissions on the parent directory.

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Greg Kroah-Hartman

ceph: fix use-after-free in __ceph_remove_cap()

2019-11-12T18:13:20+00:00

commit ea60ed6fcf29eebc78f2ce91491e6309ee005a01 upstream.

KASAN reports a use-after-free when running xfstest generic/531, with the
following trace:

[  293.903362]  kasan_report+0xe/0x20
[  293.903365]  rb_erase+0x1f/0x790
[  293.903370]  __ceph_remove_cap+0x201/0x370
[  293.903375]  __ceph_remove_caps+0x4b/0x70
[  293.903380]  ceph_evict_inode+0x4e/0x360
[  293.903386]  evict+0x169/0x290
[  293.903390]  __dentry_kill+0x16f/0x250
[  293.903394]  dput+0x1c6/0x440
[  293.903398]  __fput+0x184/0x330
[  293.903404]  task_work_run+0xb9/0xe0
[  293.903410]  exit_to_usermode_loop+0xd3/0xe0
[  293.903413]  do_syscall_64+0x1a0/0x1c0
[  293.903417]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

This happens because __ceph_remove_cap() may queue a cap release
(__ceph_queue_cap_release) which can be scheduled before that cap is
removed from the inode list with

	rb_erase(&cap->ci_node, &ci->i_caps);

And, when this finally happens, the use-after-free will occur.

This can be fixed by removing the cap from the inode list before being
removed from the session list, and thus eliminating the risk of an UAF.

Cc: stable@vger.kernel.org
Signed-off-by: Luis Henriques 
Reviewed-by: Jeff Layton 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Greg Kroah-Hartman

fs/dcache: move security_d_instantiate() behind attaching dentry to inode

2019-11-10T10:21:39+00:00

During backport 1e2e547a93a "do d_instantiate/unlock_new_inode
combinations safely", there was a error instantiating sequence of
attaching dentry to inode and calling security_d_instantiate().

Before commit ce23e640133 "->getxattr(): pass dentry and inode as
separate arguments" and b96809173e9 "security_d_instantiate(): move to
the point prior to attaching dentry to inode", security_d_instantiate()
should be called beind __d_instantiate(), otherwise it will trigger
below problem when CONFIG_SECURITY_SMACK on ext4 was enabled because
d_inode(dentry) used by ->getxattr() is NULL before __d_instantiate()
instantiate inode.

[   31.858026] BUG: unable to handle kernel paging request at ffffffffffffff70
...
[   31.882024] Call Trace:
[   31.882378]  [] ext4_xattr_get+0x8c/0x3e0
[   31.883195]  [] ext4_xattr_security_get+0x24/0x40
[   31.884086]  [] generic_getxattr+0x5b/0x90
[   31.884907]  [] smk_fetch+0xb4/0x150
[   31.885634]  [] smack_d_instantiate+0x1c2/0x550
[   31.886508]  [] security_d_instantiate+0x3a/0x80
[   31.887389]  [] d_instantiate_new+0x36/0x130
[   31.888223]  [] ext4_mkdir+0x4af/0x6a0
[   31.888928]  [] vfs_mkdir+0x100/0x280
[   31.889536]  [] SyS_mkdir+0xb6/0x170
[   31.890255]  [] ? trace_do_page_fault+0x95/0x2b0
[   31.891134]  [] entry_SYSCALL_64_fastpath+0x18/0x73

Cc:  # 3.16, 4.4
Signed-off-by: zhangyi (F) 
Signed-off-by: Greg Kroah-Hartman

cifs: Fix cifsInodeInfo lock_sem deadlock when reconnect occurs

2019-11-10T10:21:10+00:00

[ Upstream commit d46b0da7a33dd8c99d969834f682267a45444ab3 ]

There's a deadlock that is possible and can easily be seen with
a test where multiple readers open/read/close of the same file
and a disruption occurs causing reconnect.  The deadlock is due
a reader thread inside cifs_strict_readv calling down_read and
obtaining lock_sem, and then after reconnect inside
cifs_reopen_file calling down_read a second time.  If in
between the two down_read calls, a down_write comes from
another process, deadlock occurs.

        CPU0                    CPU1
        ----                    ----
cifs_strict_readv()
 down_read(&cifsi->lock_sem);
                               _cifsFileInfo_put
                                  OR
                               cifs_new_fileinfo
                                down_write(&cifsi->lock_sem);
cifs_reopen_file()
 down_read(&cifsi->lock_sem);

Fix the above by changing all down_write(lock_sem) calls to
down_write_trylock(lock_sem)/msleep() loop, which in turn
makes the second down_read call benign since it will never
block behind the writer while holding lock_sem.

Signed-off-by: Dave Wysochanski 
Suggested-by: Ronnie Sahlberg 
Reviewed--by: Ronnie Sahlberg 
Reviewed-by: Pavel Shilovsky 
Signed-off-by: Sasha Levin

xfs: Correctly invert xfs_buftarg LRU isolation logic

2019-11-06T11:09:25+00:00

commit 19957a181608d25c8f4136652d0ea00b3738972d upstream.

Due to an inverted logic mistake in xfs_buftarg_isolate()
the xfs_buffers with zero b_lru_ref will take another trip
around LRU, while isolating buffers with non-zero b_lru_ref.

Additionally those isolated buffers end up right back on the LRU
once they are released, because b_lru_ref remains elevated.

Fix that circuitous route by leaving them on the LRU
as originally intended.

Signed-off-by: Vratislav Bendel 
Reviewed-by: Brian Foster 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong 
Signed-off-by: Alex Lyakas 
Signed-off-by: Greg Kroah-Hartman

fuse: truncate pending writes on O_TRUNC

2019-11-06T11:09:18+00:00

commit e4648309b85a78f8c787457832269a8712a8673e upstream.

Make sure cached writes are not reordered around open(..., O_TRUNC), with
the obvious wrong results.

Fixes: 4d99ff8f12eb ("fuse: Turn writeback cache on")
Cc:  # v3.15+
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

fuse: flush dirty data/metadata before non-truncate setattr

2019-11-06T11:09:18+00:00

commit b24e7598db62386a95a3c8b9c75630c5d56fe077 upstream.

If writeback cache is enabled, then writes might get reordered with
chmod/chown/utimes.  The problem with this is that performing the write in
the fuse daemon might itself change some of these attributes.  In such case
the following sequence of operations will result in file ending up with the
wrong mode, for example:

  int fd = open ("suid", O_WRONLY|O_CREAT|O_EXCL);
  write (fd, "1", 1);
  fchown (fd, 0, 0);
  fchmod (fd, 04755);
  close (fd);

This patch fixes this by flushing pending writes before performing
chown/chmod/utimes.

Reported-by: Giuseppe Scrivano 
Tested-by: Giuseppe Scrivano 
Fixes: 4d99ff8f12eb ("fuse: Turn writeback cache on")
Cc:  # v3.15+
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

NFSv4: Fix leak of clp->cl_acceptor string

2019-11-06T11:09:16+00:00

[ Upstream commit 1047ec868332034d1fbcb2fae19fe6d4cb869ff2 ]

Our client can issue multiple SETCLIENTID operations to the same
server in some circumstances. Ensure that calls to
nfs4_proc_setclientid() after the first one do not overwrite the
previously allocated cl_acceptor string.

unreferenced object 0xffff888461031800 (size 32):
  comm "mount.nfs", pid 2227, jiffies 4294822467 (age 1407.749s)
  hex dump (first 32 bytes):
    6e 66 73 40 6b 6c 69 6d 74 2e 69 62 2e 31 30 31  nfs@klimt.ib.101
    35 67 72 61 6e 67 65 72 2e 6e 65 74 00 00 00 00  5granger.net....
  backtrace:
    [<00000000ab820188>] __kmalloc+0x128/0x176
    [<00000000eeaf4ec8>] gss_stringify_acceptor+0xbd/0x1a7 [auth_rpcgss]
    [<00000000e85e3382>] nfs4_proc_setclientid+0x34e/0x46c [nfsv4]
    [<000000003d9cf1fa>] nfs40_discover_server_trunking+0x7a/0xed [nfsv4]
    [<00000000b81c3787>] nfs4_discover_server_trunking+0x81/0x244 [nfsv4]
    [<000000000801b55f>] nfs4_init_client+0x1b0/0x238 [nfsv4]
    [<00000000977daf7f>] nfs4_set_client+0xfe/0x14d [nfsv4]
    [<0000000053a68a2a>] nfs4_create_server+0x107/0x1db [nfsv4]
    [<0000000088262019>] nfs4_remote_mount+0x2c/0x59 [nfsv4]
    [<00000000e84a2fd0>] legacy_get_tree+0x2d/0x4c
    [<00000000797e947c>] vfs_get_tree+0x20/0xc7
    [<00000000ecabaaa8>] fc_mount+0xe/0x36
    [<00000000f15fafc2>] vfs_kern_mount+0x74/0x8d
    [<00000000a3ff4e26>] nfs_do_root_mount+0x8a/0xa3 [nfsv4]
    [<00000000d1c2b337>] nfs4_try_mount+0x58/0xad [nfsv4]
    [<000000004c9bddee>] nfs_fs_mount+0x820/0x869 [nfs]

Fixes: f11b2a1cfbf5 ("nfs4: copy acceptor name from context ... ")
Signed-off-by: Chuck Lever 
Signed-off-by: Anna Schumaker 
Signed-off-by: Sasha Levin