linux-stable.git/include/linux, branch v5.4.35

KEYS: Don't write out to userspace while holding key semaphore

2020-04-23T08:36:45+00:00

commit d3ec10aa95819bff18a0d936b18884c7816d0914 upstream.

A lockdep circular locking dependency report was seen when running a
keyutils test:

[12537.027242] ======================================================
[12537.059309] WARNING: possible circular locking dependency detected
[12537.088148] 4.18.0-147.7.1.el8_1.x86_64+debug #1 Tainted: G OE    --------- -  -
[12537.125253] ------------------------------------------------------
[12537.153189] keyctl/25598 is trying to acquire lock:
[12537.175087] 000000007c39f96c (&mm->mmap_sem){++++}, at: __might_fault+0xc4/0x1b0
[12537.208365]
[12537.208365] but task is already holding lock:
[12537.234507] 000000003de5b58d (&type->lock_class){++++}, at: keyctl_read_key+0x15a/0x220
[12537.270476]
[12537.270476] which lock already depends on the new lock.
[12537.270476]
[12537.307209]
[12537.307209] the existing dependency chain (in reverse order) is:
[12537.340754]
[12537.340754] -> #3 (&type->lock_class){++++}:
[12537.367434]        down_write+0x4d/0x110
[12537.385202]        __key_link_begin+0x87/0x280
[12537.405232]        request_key_and_link+0x483/0xf70
[12537.427221]        request_key+0x3c/0x80
[12537.444839]        dns_query+0x1db/0x5a5 [dns_resolver]
[12537.468445]        dns_resolve_server_name_to_ip+0x1e1/0x4d0 [cifs]
[12537.496731]        cifs_reconnect+0xe04/0x2500 [cifs]
[12537.519418]        cifs_readv_from_socket+0x461/0x690 [cifs]
[12537.546263]        cifs_read_from_socket+0xa0/0xe0 [cifs]
[12537.573551]        cifs_demultiplex_thread+0x311/0x2db0 [cifs]
[12537.601045]        kthread+0x30c/0x3d0
[12537.617906]        ret_from_fork+0x3a/0x50
[12537.636225]
[12537.636225] -> #2 (root_key_user.cons_lock){+.+.}:
[12537.664525]        __mutex_lock+0x105/0x11f0
[12537.683734]        request_key_and_link+0x35a/0xf70
[12537.705640]        request_key+0x3c/0x80
[12537.723304]        dns_query+0x1db/0x5a5 [dns_resolver]
[12537.746773]        dns_resolve_server_name_to_ip+0x1e1/0x4d0 [cifs]
[12537.775607]        cifs_reconnect+0xe04/0x2500 [cifs]
[12537.798322]        cifs_readv_from_socket+0x461/0x690 [cifs]
[12537.823369]        cifs_read_from_socket+0xa0/0xe0 [cifs]
[12537.847262]        cifs_demultiplex_thread+0x311/0x2db0 [cifs]
[12537.873477]        kthread+0x30c/0x3d0
[12537.890281]        ret_from_fork+0x3a/0x50
[12537.908649]
[12537.908649] -> #1 (&tcp_ses->srv_mutex){+.+.}:
[12537.935225]        __mutex_lock+0x105/0x11f0
[12537.954450]        cifs_call_async+0x102/0x7f0 [cifs]
[12537.977250]        smb2_async_readv+0x6c3/0xc90 [cifs]
[12538.000659]        cifs_readpages+0x120a/0x1e50 [cifs]
[12538.023920]        read_pages+0xf5/0x560
[12538.041583]        __do_page_cache_readahead+0x41d/0x4b0
[12538.067047]        ondemand_readahead+0x44c/0xc10
[12538.092069]        filemap_fault+0xec1/0x1830
[12538.111637]        __do_fault+0x82/0x260
[12538.129216]        do_fault+0x419/0xfb0
[12538.146390]        __handle_mm_fault+0x862/0xdf0
[12538.167408]        handle_mm_fault+0x154/0x550
[12538.187401]        __do_page_fault+0x42f/0xa60
[12538.207395]        do_page_fault+0x38/0x5e0
[12538.225777]        page_fault+0x1e/0x30
[12538.243010]
[12538.243010] -> #0 (&mm->mmap_sem){++++}:
[12538.267875]        lock_acquire+0x14c/0x420
[12538.286848]        __might_fault+0x119/0x1b0
[12538.306006]        keyring_read_iterator+0x7e/0x170
[12538.327936]        assoc_array_subtree_iterate+0x97/0x280
[12538.352154]        keyring_read+0xe9/0x110
[12538.370558]        keyctl_read_key+0x1b9/0x220
[12538.391470]        do_syscall_64+0xa5/0x4b0
[12538.410511]        entry_SYSCALL_64_after_hwframe+0x6a/0xdf
[12538.435535]
[12538.435535] other info that might help us debug this:
[12538.435535]
[12538.472829] Chain exists of:
[12538.472829]   &mm->mmap_sem --> root_key_user.cons_lock --> &type->lock_class
[12538.472829]
[12538.524820]  Possible unsafe locking scenario:
[12538.524820]
[12538.551431]        CPU0                    CPU1
[12538.572654]        ----                    ----
[12538.595865]   lock(&type->lock_class);
[12538.613737]                                lock(root_key_user.cons_lock);
[12538.644234]                                lock(&type->lock_class);
[12538.672410]   lock(&mm->mmap_sem);
[12538.687758]
[12538.687758]  *** DEADLOCK ***
[12538.687758]
[12538.714455] 1 lock held by keyctl/25598:
[12538.732097]  #0: 000000003de5b58d (&type->lock_class){++++}, at: keyctl_read_key+0x15a/0x220
[12538.770573]
[12538.770573] stack backtrace:
[12538.790136] CPU: 2 PID: 25598 Comm: keyctl Kdump: loaded Tainted: G
[12538.844855] Hardware name: HP ProLiant DL360 Gen9/ProLiant DL360 Gen9, BIOS P89 12/27/2015
[12538.881963] Call Trace:
[12538.892897]  dump_stack+0x9a/0xf0
[12538.907908]  print_circular_bug.isra.25.cold.50+0x1bc/0x279
[12538.932891]  ? save_trace+0xd6/0x250
[12538.948979]  check_prev_add.constprop.32+0xc36/0x14f0
[12538.971643]  ? keyring_compare_object+0x104/0x190
[12538.992738]  ? check_usage+0x550/0x550
[12539.009845]  ? sched_clock+0x5/0x10
[12539.025484]  ? sched_clock_cpu+0x18/0x1e0
[12539.043555]  __lock_acquire+0x1f12/0x38d0
[12539.061551]  ? trace_hardirqs_on+0x10/0x10
[12539.080554]  lock_acquire+0x14c/0x420
[12539.100330]  ? __might_fault+0xc4/0x1b0
[12539.119079]  __might_fault+0x119/0x1b0
[12539.135869]  ? __might_fault+0xc4/0x1b0
[12539.153234]  keyring_read_iterator+0x7e/0x170
[12539.172787]  ? keyring_read+0x110/0x110
[12539.190059]  assoc_array_subtree_iterate+0x97/0x280
[12539.211526]  keyring_read+0xe9/0x110
[12539.227561]  ? keyring_gc_check_iterator+0xc0/0xc0
[12539.249076]  keyctl_read_key+0x1b9/0x220
[12539.266660]  do_syscall_64+0xa5/0x4b0
[12539.283091]  entry_SYSCALL_64_after_hwframe+0x6a/0xdf

One way to prevent this deadlock scenario from happening is to not
allow writing to userspace while holding the key semaphore. Instead,
an internal buffer is allocated for getting the keys out from the
read method first before copying them out to userspace without holding
the lock.

That requires taking out the __user modifier from all the relevant
read methods as well as additional changes to not use any userspace
write helpers. That is,

  1) The put_user() call is replaced by a direct copy.
  2) The copy_to_user() call is replaced by memcpy().
  3) All the fault handling code is removed.

Compiling on a x86-64 system, the size of the rxrpc_read() function is
reduced from 3795 bytes to 2384 bytes with this patch.

Fixes: ^1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Jarkko Sakkinen 
Signed-off-by: Waiman Long 
Signed-off-by: David Howells 
Signed-off-by: Greg Kroah-Hartman

compiler.h: fix error in BUILD_BUG_ON() reporting

2020-04-23T08:36:37+00:00

[ Upstream commit af9c5d2e3b355854ff0e4acfbfbfadcd5198a349 ]

compiletime_assert() uses __LINE__ to create a unique function name.  This
means that if you have more than one BUILD_BUG_ON() in the same source
line (which can happen if they appear e.g.  in a macro), then the error
message from the compiler might output the wrong condition.

For this source file:

	#include 

	#define macro() \
		BUILD_BUG_ON(1); \
		BUILD_BUG_ON(0);

	void foo()
	{
		macro();
	}

gcc would output:

./include/linux/compiler.h:350:38: error: call to `__compiletime_assert_9' declared with attribute error: BUILD_BUG_ON failed: 0
  _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)

However, it was not the BUILD_BUG_ON(0) that failed, so it should say 1
instead of 0. With this patch, we use __COUNTER__ instead of __LINE__, so
each BUILD_BUG_ON() gets a different function name and the correct
condition is printed:

./include/linux/compiler.h:350:38: error: call to `__compiletime_assert_0' declared with attribute error: BUILD_BUG_ON failed: 1
  _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)

Signed-off-by: Vegard Nossum 
Signed-off-by: Andrew Morton 
Reviewed-by: Masahiro Yamada 
Reviewed-by: Daniel Santos 
Cc: Rasmus Villemoes 
Cc: Ian Abbott 
Cc: Joe Perches 
Link: http://lkml.kernel.org/r/20200331112637.25047-1-vegard.nossum@oracle.com
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

percpu_counter: fix a data race at vm_committed_as

2020-04-23T08:36:37+00:00

[ Upstream commit 7e2345200262e4a6056580f0231cccdaffc825f3 ]

"vm_committed_as.count" could be accessed concurrently as reported by
KCSAN,

 BUG: KCSAN: data-race in __vm_enough_memory / percpu_counter_add_batch

 write to 0xffffffff9451c538 of 8 bytes by task 65879 on cpu 35:
  percpu_counter_add_batch+0x83/0xd0
  percpu_counter_add_batch at lib/percpu_counter.c:91
  __vm_enough_memory+0xb9/0x260
  dup_mm+0x3a4/0x8f0
  copy_process+0x2458/0x3240
  _do_fork+0xaa/0x9f0
  __do_sys_clone+0x125/0x160
  __x64_sys_clone+0x70/0x90
  do_syscall_64+0x91/0xb05
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

 read to 0xffffffff9451c538 of 8 bytes by task 66773 on cpu 19:
  __vm_enough_memory+0x199/0x260
  percpu_counter_read_positive at include/linux/percpu_counter.h:81
  (inlined by) __vm_enough_memory at mm/util.c:839
  mmap_region+0x1b2/0xa10
  do_mmap+0x45c/0x700
  vm_mmap_pgoff+0xc0/0x130
  ksys_mmap_pgoff+0x6e/0x300
  __x64_sys_mmap+0x33/0x40
  do_syscall_64+0x91/0xb05
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

The read is outside percpu_counter::lock critical section which results in
a data race.  Fix it by adding a READ_ONCE() in
percpu_counter_read_positive() which could also service as the existing
compiler memory barrier.

Signed-off-by: Qian Cai 
Signed-off-by: Andrew Morton 
Acked-by: Marco Elver 
Link: http://lkml.kernel.org/r/1582302724-2804-1-git-send-email-cai@lca.pw
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

include/linux/swapops.h: correct guards for non_swap_entry()

2020-04-23T08:36:37+00:00

[ Upstream commit 3f3673d7d324d872d9d8ddb73b3e5e47fbf12e0d ]

If CONFIG_DEVICE_PRIVATE is defined, but neither CONFIG_MEMORY_FAILURE nor
CONFIG_MIGRATION, then non_swap_entry() will return 0, meaning that the
condition (non_swap_entry(entry) && is_device_private_entry(entry)) in
zap_pte_range() will never be true even if the entry is a device private
one.

Equally any other code depending on non_swap_entry() will not function as
expected.

I originally spotted this just by looking at the code, I haven't actually
observed any problems.

Looking a bit more closely it appears that actually this situation
(currently at least) cannot occur:

DEVICE_PRIVATE depends on ZONE_DEVICE
ZONE_DEVICE depends on MEMORY_HOTREMOVE
MEMORY_HOTREMOVE depends on MIGRATION

Fixes: 5042db43cc26 ("mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory")
Signed-off-by: Steven Price 
Signed-off-by: Andrew Morton 
Cc: Jérôme Glisse 
Cc: Arnd Bergmann 
Cc: Dan Williams 
Cc: John Hubbard 
Link: http://lkml.kernel.org/r/20200305130550.22693-1-steven.price@arm.com
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

mm/hugetlb: fix build failure with HUGETLB_PAGE but not HUGEBTLBFS

2020-04-23T08:36:36+00:00

[ Upstream commit bb297bb2de517e41199185021f043bbc5d75b377 ]

When CONFIG_HUGETLB_PAGE is set but not CONFIG_HUGETLBFS, the following
build failure is encoutered:

  In file included from arch/powerpc/mm/fault.c:33:0:
  include/linux/hugetlb.h: In function 'hstate_inode':
  include/linux/hugetlb.h:477:9: error: implicit declaration of function 'HUGETLBFS_SB' [-Werror=implicit-function-declaration]
    return HUGETLBFS_SB(i->i_sb)->hstate;
           ^
  include/linux/hugetlb.h:477:30: error: invalid type argument of '->' (have 'int')
    return HUGETLBFS_SB(i->i_sb)->hstate;
                                ^

Gate hstate_inode() with CONFIG_HUGETLBFS instead of CONFIG_HUGETLB_PAGE.

Fixes: a137e1cc6d6e ("hugetlbfs: per mount huge page sizes")
Reported-by: kbuild test robot 
Signed-off-by: Christophe Leroy 
Signed-off-by: Andrew Morton 
Reviewed-by: Mike Kravetz 
Cc: Baoquan He 
Cc: Nishanth Aravamudan 
Cc: Nick Piggin 
Cc: Adam Litke 
Cc: Andi Kleen 
Link: http://lkml.kernel.org/r/7e8c3a3c9a587b9cd8a2f146df32a421b961f3a2.1584432148.git.christophe.leroy@c-s.fr
Link: https://patchwork.ozlabs.org/patch/1255548/#2386036
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

f2fs: Add a new CP flag to help fsck fix resize SPO issues

2020-04-23T08:36:33+00:00

[ Upstream commit c84ef3c5e65ccf99a7a91a4d731ebb5d6331a178 ]

Add and set a new CP flag CP_RESIZEFS_FLAG during
online resize FS to help fsck fix the metadata mismatch
that may happen due to SPO during resize, where SB
got updated but CP data couldn't be written yet.

fsck errors -
Info: CKPT version = 6ed7bccb
        Wrong user_block_count(2233856)
[f2fs_do_mount:3365] Checkpoint is polluted

Signed-off-by: Sahitya Tummala 
Reviewed-by: Chao Yu 
Signed-off-by: Jaegeuk Kim 
Signed-off-by: Sasha Levin

ext4: use non-movable memory for superblock readahead

2020-04-23T08:36:15+00:00

commit d87f639258a6a5980183f11876c884931ad93da2 upstream.

Since commit a8ac900b8163 ("ext4: use non-movable memory for the
superblock") buffers for ext4 superblock were allocated using
the sb_bread_unmovable() helper which allocated buffer heads
out of non-movable memory blocks. It was necessarily to not block
page migrations and do not cause cma allocation failures.

However commit 85c8f176a611 ("ext4: preload block group descriptors")
broke this by introducing pre-reading of the ext4 superblock.
The problem is that __breadahead() is using __getblk() underneath,
which allocates buffer heads out of movable memory.

It resulted in page migration failures I've seen on a machine
with an ext4 partition and a preallocated cma area.

Fix this by introducing sb_breadahead_unmovable() and
__breadahead_gfp() helpers which use non-movable memory for buffer
head allocations and use them for the ext4 superblock readahead.

Reviewed-by: Andreas Dilger 
Fixes: 85c8f176a611 ("ext4: preload block group descriptors")
Signed-off-by: Roman Gushchin 
Link: https://lore.kernel.org/r/20200229001411.128010-1-guro@fb.com
Signed-off-by: Theodore Ts'o 
Signed-off-by: Greg Kroah-Hartman

xarray: Fix early termination of xas_for_each_marked

2020-04-17T08:50:18+00:00

commit 7e934cf5ace1dceeb804f7493fa28bb697ed3c52 upstream.

xas_for_each_marked() is using entry == NULL as a termination condition
of the iteration. When xas_for_each_marked() is used protected only by
RCU, this can however race with xas_store(xas, NULL) in the following
way:

TASK1                                   TASK2
page_cache_delete()         	        find_get_pages_range_tag()
                                          xas_for_each_marked()
                                            xas_find_marked()
                                              off = xas_find_chunk()

  xas_store(&xas, NULL)
    xas_init_marks(&xas);
    ...
    rcu_assign_pointer(*slot, NULL);
                                              entry = xa_entry(off);

And thus xas_for_each_marked() terminates prematurely possibly leading
to missed entries in the iteration (translating to missing writeback of
some pages or a similar problem).

If we find a NULL entry that has been marked, skip it (unless we're trying
to allocate an entry).

Reported-by: Jan Kara 
CC: stable@vger.kernel.org
Fixes: ef8e5717db01 ("page cache: Convert delete_batch to XArray")
Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Greg Kroah-Hartman

signal: Extend exec_id to 64bits

2020-04-17T08:50:12+00:00

commit d1e7fd6462ca9fc76650fbe6ca800e35b24267da upstream.

Replace the 32bit exec_id with a 64bit exec_id to make it impossible
to wrap the exec_id counter.  With care an attacker can cause exec_id
wrap and send arbitrary signals to a newly exec'd parent.  This
bypasses the signal sending checks if the parent changes their
credentials during exec.

The severity of this problem can been seen that in my limited testing
of a 32bit exec_id it can take as little as 19s to exec 65536 times.
Which means that it can take as little as 14 days to wrap a 32bit
exec_id.  Adam Zabrocki has succeeded wrapping the self_exe_id in 7
days.  Even my slower timing is in the uptime of a typical server.
Which means self_exec_id is simply a speed bump today, and if exec
gets noticably faster self_exec_id won't even be a speed bump.

Extending self_exec_id to 64bits introduces a problem on 32bit
architectures where reading self_exec_id is no longer atomic and can
take two read instructions.  Which means that is is possible to hit
a window where the read value of exec_id does not match the written
value.  So with very lucky timing after this change this still
remains expoiltable.

I have updated the update of exec_id on exec to use WRITE_ONCE
and the read of exec_id in do_notify_parent to use READ_ONCE
to make it clear that there is no locking between these two
locations.

Link: https://lore.kernel.org/kernel-hardening/20200324215049.GA3710@pi3.com.pl
Fixes: 2.3.23pre2
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Greg Kroah-Hartman

cpu/hotplug: Ignore pm_wakeup_pending() for disable_nonboot_cpus()

2020-04-17T08:50:11+00:00

commit e98eac6ff1b45e4e73f2e6031b37c256ccb5d36b upstream.

A recent change to freeze_secondary_cpus() which added an early abort if a
wakeup is pending missed the fact that the function is also invoked for
shutdown, reboot and kexec via disable_nonboot_cpus().

In case of disable_nonboot_cpus() the wakeup event needs to be ignored as
the purpose is to terminate the currently running kernel.

Add a 'suspend' argument which is only set when the freeze is in context of
a suspend operation. If not set then an eventually pending wakeup event is
ignored.

Fixes: a66d955e910a ("cpu/hotplug: Abort disabling secondary CPUs if wakeup is pending")
Reported-by: Boqun Feng 
Signed-off-by: Thomas Gleixner 
Cc: Pavankumar Kondeti 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/874kuaxdiz.fsf@nanos.tec.linutronix.de
Signed-off-by: Greg Kroah-Hartman