linux-stable.git/fs, branch v4.4.240 Linux kernel stable tree reiserfs: Fix oops during mount 2020-10-17T09:03:31+00:00 Jan Kara jack@suse.cz 2020-09-30T15:08:20+00:00 265e6dc04875bc757f5547cedd459ca92dfd0034 commit c2bb80b8bdd04dfe32364b78b61b6a47f717af52 upstream. With suitably crafted reiserfs image and mount command reiserfs will crash when trying to verify that XATTR_ROOT directory can be looked up in / as that recurses back to xattr code like: xattr_lookup+0x24/0x280 fs/reiserfs/xattr.c:395 reiserfs_xattr_get+0x89/0x540 fs/reiserfs/xattr.c:677 reiserfs_get_acl+0x63/0x690 fs/reiserfs/xattr_acl.c:209 get_acl+0x152/0x2e0 fs/posix_acl.c:141 check_acl fs/namei.c:277 [inline] acl_permission_check fs/namei.c:309 [inline] generic_permission+0x2ba/0x550 fs/namei.c:353 do_inode_permission fs/namei.c:398 [inline] inode_permission+0x234/0x4a0 fs/namei.c:463 lookup_one_len+0xa6/0x200 fs/namei.c:2557 reiserfs_lookup_privroot+0x85/0x1e0 fs/reiserfs/xattr.c:972 reiserfs_fill_super+0x2b51/0x3240 fs/reiserfs/super.c:2176 mount_bdev+0x24f/0x360 fs/super.c:1417 Fix the problem by bailing from reiserfs_xattr_get() when xattrs are not yet initialized. CC: stable@vger.kernel.org Reported-by: syzbot+9b33c9b118d77ff59b6f@syzkaller.appspotmail.com Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit c2bb80b8bdd04dfe32364b78b61b6a47f717af52 upstream.

With suitably crafted reiserfs image and mount command reiserfs will
crash when trying to verify that XATTR_ROOT directory can be looked up
in / as that recurses back to xattr code like:

 xattr_lookup+0x24/0x280 fs/reiserfs/xattr.c:395
 reiserfs_xattr_get+0x89/0x540 fs/reiserfs/xattr.c:677
 reiserfs_get_acl+0x63/0x690 fs/reiserfs/xattr_acl.c:209
 get_acl+0x152/0x2e0 fs/posix_acl.c:141
 check_acl fs/namei.c:277 [inline]
 acl_permission_check fs/namei.c:309 [inline]
 generic_permission+0x2ba/0x550 fs/namei.c:353
 do_inode_permission fs/namei.c:398 [inline]
 inode_permission+0x234/0x4a0 fs/namei.c:463
 lookup_one_len+0xa6/0x200 fs/namei.c:2557
 reiserfs_lookup_privroot+0x85/0x1e0 fs/reiserfs/xattr.c:972
 reiserfs_fill_super+0x2b51/0x3240 fs/reiserfs/super.c:2176
 mount_bdev+0x24f/0x360 fs/super.c:1417

Fix the problem by bailing from reiserfs_xattr_get() when xattrs are not
yet initialized.

CC: stable@vger.kernel.org
Reported-by: syzbot+9b33c9b118d77ff59b6f@syzkaller.appspotmail.com
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
reiserfs: Initialize inode keys properly 2020-10-17T09:03:31+00:00 Jan Kara jack@suse.cz 2020-09-21T13:08:50+00:00 0d6877c37dc0892378684477b3f927b87e3607a8 commit 4443390e08d34d5771ab444f601cf71b3c9634a4 upstream. reiserfs_read_locked_inode() didn't initialize key length properly. Use _make_cpu_key() macro for key initialization so that all key member are properly initialized. CC: stable@vger.kernel.org Reported-by: syzbot+d94d02749498bb7bab4b@syzkaller.appspotmail.com Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 4443390e08d34d5771ab444f601cf71b3c9634a4 upstream.

reiserfs_read_locked_inode() didn't initialize key length properly. Use
_make_cpu_key() macro for key initialization so that all key member are
properly initialized.

CC: stable@vger.kernel.org
Reported-by: syzbot+d94d02749498bb7bab4b@syzkaller.appspotmail.com
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ep_create_wakeup_source(): dentry name can change under you... 2020-10-14T07:46:21+00:00 Al Viro viro@zeniv.linux.org.uk 2020-09-24T23:41:58+00:00 97f8be925b061241196e78c68455914e04dc2a4b commit 3701cb59d892b88d569427586f01491552f377b1 upstream. or get freed, for that matter, if it's a long (separately stored) name. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 3701cb59d892b88d569427586f01491552f377b1 upstream.

or get freed, for that matter, if it's a long (separately stored)
name.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
epoll: EPOLL_CTL_ADD: close the race in decision to take fast path 2020-10-14T07:46:21+00:00 Al Viro viro@zeniv.linux.org.uk 2020-09-10T12:33:27+00:00 199140bc63cd00533f1d04ce9ae72a21123530ec commit fe0a916c1eae8e17e86c3753d13919177d63ed7e upstream. Checking for the lack of epitems refering to the epoll we want to insert into is not enough; we might have an insertion of that epoll into another one that has already collected the set of files to recheck for excessive reverse paths, but hasn't gotten to creating/inserting the epitem for it. However, any such insertion in progress can be detected - it will update the generation count in our epoll when it's done looking through it for files to check. That gets done under ->mtx of our epoll and that allows us to detect that safely. We are *not* holding epmutex here, so the generation count is not stable. However, since both the update of ep->gen by loop check and (later) insertion into ->f_ep_link are done with ep->mtx held, we are fine - the sequence is grab epmutex bump loop_check_gen ... grab tep->mtx // 1 tep->gen = loop_check_gen ... drop tep->mtx // 2 ... grab tep->mtx // 3 ... insert into ->f_ep_link ... drop tep->mtx // 4 bump loop_check_gen drop epmutex and if the fastpath check in another thread happens for that eventpoll, it can come * before (1) - in that case fastpath is just fine * after (4) - we'll see non-empty ->f_ep_link, slow path taken * between (2) and (3) - loop_check_gen is stable, with ->mtx providing barriers and we end up taking slow path. Note that ->f_ep_link emptiness check is slightly racy - we are protected against insertions into that list, but removals can happen right under us. Not a problem - in the worst case we'll end up taking a slow path for no good reason. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit fe0a916c1eae8e17e86c3753d13919177d63ed7e upstream.

Checking for the lack of epitems refering to the epoll we want to insert into
is not enough; we might have an insertion of that epoll into another one that
has already collected the set of files to recheck for excessive reverse paths,
but hasn't gotten to creating/inserting the epitem for it.

However, any such insertion in progress can be detected - it will update the
generation count in our epoll when it's done looking through it for files
to check.  That gets done under ->mtx of our epoll and that allows us to
detect that safely.

We are *not* holding epmutex here, so the generation count is not stable.
However, since both the update of ep->gen by loop check and (later)
insertion into ->f_ep_link are done with ep->mtx held, we are fine -
the sequence is
	grab epmutex
	bump loop_check_gen
	...
	grab tep->mtx		// 1
	tep->gen = loop_check_gen
	...
	drop tep->mtx		// 2
	...
	grab tep->mtx		// 3
	...
	insert into ->f_ep_link
	...
	drop tep->mtx		// 4
	bump loop_check_gen
	drop epmutex
and if the fastpath check in another thread happens for that
eventpoll, it can come
	* before (1) - in that case fastpath is just fine
	* after (4) - we'll see non-empty ->f_ep_link, slow path
taken
	* between (2) and (3) - loop_check_gen is stable,
with ->mtx providing barriers and we end up taking slow path.

Note that ->f_ep_link emptiness check is slightly racy - we are protected
against insertions into that list, but removals can happen right under us.
Not a problem - in the worst case we'll end up taking a slow path for
no good reason.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
epoll: replace ->visited/visited_list with generation count 2020-10-14T07:46:21+00:00 Al Viro viro@zeniv.linux.org.uk 2020-09-10T12:30:05+00:00 648bffab761667d1d1ddb5dbb7585e250ddd49b9 commit 18306c404abe18a0972587a6266830583c60c928 upstream. removes the need to clear it, along with the races. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 18306c404abe18a0972587a6266830583c60c928 upstream.

removes the need to clear it, along with the races.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
epoll: do not insert into poll queues until all sanity checks are done 2020-10-14T07:46:20+00:00 Al Viro viro@zeniv.linux.org.uk 2020-09-10T02:25:06+00:00 ea984dfe0e7978cd294eb6a640ac27fa1834ac8d commit f8d4f44df056c5b504b0d49683fb7279218fd207 upstream. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit f8d4f44df056c5b504b0d49683fb7279218fd207 upstream.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
nfs: Fix security label length not being reset 2020-10-14T07:46:20+00:00 Jeffrey Mitchell jeffrey.mitchell@starlab.io 2020-09-15T21:42:52+00:00 c8bf391fcdd18466363d493922a9ba500aeb17fd [ Upstream commit d33030e2ee3508d65db5644551435310df86010e ] nfs_readdir_page_filler() iterates over entries in a directory, reusing the same security label buffer, but does not reset the buffer's length. This causes decode_attr_security_label() to return -ERANGE if an entry's security label is longer than the previous one's. This error, in nfs4_decode_dirent(), only gets passed up as -EAGAIN, which causes another failed attempt to copy into the buffer. The second error is ignored and the remaining entries do not show up in ls, specifically the getdents64() syscall. Reproduce by creating multiple files in NFS and giving one of the later files a longer security label. ls will not see that file nor any that are added afterwards, though they will exist on the backend. In nfs_readdir_page_filler(), reset security label buffer length before every reuse Signed-off-by: Jeffrey Mitchell <jeffrey.mitchell@starlab.io> Fixes: b4487b935452 ("nfs: Fix getxattr kernel panic and memory overflow") Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit d33030e2ee3508d65db5644551435310df86010e ]

nfs_readdir_page_filler() iterates over entries in a directory, reusing
the same security label buffer, but does not reset the buffer's length.
This causes decode_attr_security_label() to return -ERANGE if an entry's
security label is longer than the previous one's. This error, in
nfs4_decode_dirent(), only gets passed up as -EAGAIN, which causes another
failed attempt to copy into the buffer. The second error is ignored and
the remaining entries do not show up in ls, specifically the getdents64()
syscall.

Reproduce by creating multiple files in NFS and giving one of the later
files a longer security label. ls will not see that file nor any that are
added afterwards, though they will exist on the backend.

In nfs_readdir_page_filler(), reset security label buffer length before
every reuse

Signed-off-by: Jeffrey Mitchell <jeffrey.mitchell@starlab.io>
Fixes: b4487b935452 ("nfs: Fix getxattr kernel panic and memory overflow")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
ceph: fix potential race in ceph_check_caps 2020-10-01T09:11:56+00:00 Jeff Layton jlayton@kernel.org 2020-03-20T20:45:45+00:00 da1935ae27d6af755d561204cf4b2ba2cf39fbd0 [ Upstream commit dc3da0461cc4b76f2d0c5b12247fcb3b520edbbf ] Nothing ensures that session will still be valid by the time we dereference the pointer. Take and put a reference. In principle, we should always be able to get a reference here, but throw a warning if that's ever not the case. Signed-off-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit dc3da0461cc4b76f2d0c5b12247fcb3b520edbbf ]

Nothing ensures that session will still be valid by the time we
dereference the pointer. Take and put a reference.

In principle, we should always be able to get a reference here, but
throw a warning if that's ever not the case.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
fuse: don't check refcount after stealing page 2020-10-01T09:11:55+00:00 Miklos Szeredi mszeredi@redhat.com 2020-05-19T12:50:37+00:00 1cec5992cc34aa082541ff10b0ba0356e1e3c045 [ Upstream commit 32f98877c57bee6bc27f443a96f49678a2cd6a50 ] page_count() is unstable. Unless there has been an RCU grace period between when the page was removed from the page cache and now, a speculative reference may exist from the page cache. Reported-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 32f98877c57bee6bc27f443a96f49678a2cd6a50 ]

page_count() is unstable.  Unless there has been an RCU grace period
between when the page was removed from the page cache and now, a
speculative reference may exist from the page cache.

Reported-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
bdev: Reduce time holding bd_mutex in sync in blkdev_close() 2020-10-01T09:11:54+00:00 Douglas Anderson dianders@chromium.org 2020-03-24T21:48:27+00:00 bd1449b9b8ddf1bbb3cf528c4bf3d3eef026b634 [ Upstream commit b849dd84b6ccfe32622988b79b7b073861fcf9f7 ] While trying to "dd" to the block device for a USB stick, I encountered a hung task warning (blocked for > 120 seconds). I managed to come up with an easy way to reproduce this on my system (where /dev/sdb is the block device for my USB stick) with: while true; do dd if=/dev/zero of=/dev/sdb bs=4M; done With my reproduction here are the relevant bits from the hung task detector: INFO: task udevd:294 blocked for more than 122 seconds. ... udevd D 0 294 1 0x00400008 Call trace: ... mutex_lock_nested+0x40/0x50 __blkdev_get+0x7c/0x3d4 blkdev_get+0x118/0x138 blkdev_open+0x94/0xa8 do_dentry_open+0x268/0x3a0 vfs_open+0x34/0x40 path_openat+0x39c/0xdf4 do_filp_open+0x90/0x10c do_sys_open+0x150/0x3c8 ... ... Showing all locks held in the system: ... 1 lock held by dd/2798: #0: ffffff814ac1a3b8 (&bdev->bd_mutex){+.+.}, at: __blkdev_put+0x50/0x204 ... dd D 0 2798 2764 0x00400208 Call trace: ... schedule+0x8c/0xbc io_schedule+0x1c/0x40 wait_on_page_bit_common+0x238/0x338 __lock_page+0x5c/0x68 write_cache_pages+0x194/0x500 generic_writepages+0x64/0xa4 blkdev_writepages+0x24/0x30 do_writepages+0x48/0xa8 __filemap_fdatawrite_range+0xac/0xd8 filemap_write_and_wait+0x30/0x84 __blkdev_put+0x88/0x204 blkdev_put+0xc4/0xe4 blkdev_close+0x28/0x38 __fput+0xe0/0x238 ____fput+0x1c/0x28 task_work_run+0xb0/0xe4 do_notify_resume+0xfc0/0x14bc work_pending+0x8/0x14 The problem appears related to the fact that my USB disk is terribly slow and that I have a lot of RAM in my system to cache things. Specifically my writes seem to be happening at ~15 MB/s and I've got ~4 GB of RAM in my system that can be used for buffering. To write 4 GB of buffer to disk thus takes ~4000 MB / ~15 MB/s = ~267 seconds. The 267 second number is a problem because in __blkdev_put() we call sync_blockdev() while holding the bd_mutex. Any other callers who want the bd_mutex will be blocked for the whole time. The problem is made worse because I believe blkdev_put() specifically tells other tasks (namely udev) to go try to access the device at right around the same time we're going to hold the mutex for a long time. Putting some traces around this (after disabling the hung task detector), I could confirm: dd: 437.608600: __blkdev_put() right before sync_blockdev() for sdb udevd: 437.623901: blkdev_open() right before blkdev_get() for sdb dd: 661.468451: __blkdev_put() right after sync_blockdev() for sdb udevd: 663.820426: blkdev_open() right after blkdev_get() for sdb A simple fix for this is to realize that sync_blockdev() works fine if you're not holding the mutex. Also, it's not the end of the world if you sync a little early (though it can have performance impacts). Thus we can make a guess that we're going to need to do the sync and then do it without holding the mutex. We still do one last sync with the mutex but it should be much, much faster. With this, my hung task warnings for my test case are gone. Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Guenter Roeck <groeck@chromium.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit b849dd84b6ccfe32622988b79b7b073861fcf9f7 ]

While trying to "dd" to the block device for a USB stick, I
encountered a hung task warning (blocked for > 120 seconds).  I
managed to come up with an easy way to reproduce this on my system
(where /dev/sdb is the block device for my USB stick) with:

  while true; do dd if=/dev/zero of=/dev/sdb bs=4M; done

With my reproduction here are the relevant bits from the hung task
detector:

 INFO: task udevd:294 blocked for more than 122 seconds.
 ...
 udevd           D    0   294      1 0x00400008
 Call trace:
  ...
  mutex_lock_nested+0x40/0x50
  __blkdev_get+0x7c/0x3d4
  blkdev_get+0x118/0x138
  blkdev_open+0x94/0xa8
  do_dentry_open+0x268/0x3a0
  vfs_open+0x34/0x40
  path_openat+0x39c/0xdf4
  do_filp_open+0x90/0x10c
  do_sys_open+0x150/0x3c8
  ...

 ...
 Showing all locks held in the system:
 ...
 1 lock held by dd/2798:
  #0: ffffff814ac1a3b8 (&bdev->bd_mutex){+.+.}, at: __blkdev_put+0x50/0x204
 ...
 dd              D    0  2798   2764 0x00400208
 Call trace:
  ...
  schedule+0x8c/0xbc
  io_schedule+0x1c/0x40
  wait_on_page_bit_common+0x238/0x338
  __lock_page+0x5c/0x68
  write_cache_pages+0x194/0x500
  generic_writepages+0x64/0xa4
  blkdev_writepages+0x24/0x30
  do_writepages+0x48/0xa8
  __filemap_fdatawrite_range+0xac/0xd8
  filemap_write_and_wait+0x30/0x84
  __blkdev_put+0x88/0x204
  blkdev_put+0xc4/0xe4
  blkdev_close+0x28/0x38
  __fput+0xe0/0x238
  ____fput+0x1c/0x28
  task_work_run+0xb0/0xe4
  do_notify_resume+0xfc0/0x14bc
  work_pending+0x8/0x14

The problem appears related to the fact that my USB disk is terribly
slow and that I have a lot of RAM in my system to cache things.
Specifically my writes seem to be happening at ~15 MB/s and I've got
~4 GB of RAM in my system that can be used for buffering.  To write 4
GB of buffer to disk thus takes ~4000 MB / ~15 MB/s = ~267 seconds.

The 267 second number is a problem because in __blkdev_put() we call
sync_blockdev() while holding the bd_mutex.  Any other callers who
want the bd_mutex will be blocked for the whole time.

The problem is made worse because I believe blkdev_put() specifically
tells other tasks (namely udev) to go try to access the device at right
around the same time we're going to hold the mutex for a long time.

Putting some traces around this (after disabling the hung task detector),
I could confirm:
 dd:    437.608600: __blkdev_put() right before sync_blockdev() for sdb
 udevd: 437.623901: blkdev_open() right before blkdev_get() for sdb
 dd:    661.468451: __blkdev_put() right after sync_blockdev() for sdb
 udevd: 663.820426: blkdev_open() right after blkdev_get() for sdb

A simple fix for this is to realize that sync_blockdev() works fine if
you're not holding the mutex.  Also, it's not the end of the world if
you sync a little early (though it can have performance impacts).
Thus we can make a guess that we're going to need to do the sync and
then do it without holding the mutex.  We still do one last sync with
the mutex but it should be much, much faster.

With this, my hung task warnings for my test case are gone.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>