linux-stable.git/kernel, branch v5.6.18

uprobes: ensure that uprobe->offset and ->ref_ctr_offset are properly aligned

2020-06-10T18:22:53+00:00

commit 013b2deba9a6b80ca02f4fafd7dedf875e9b4450 upstream.

uprobe_write_opcode() must not cross page boundary; prepare_uprobe()
relies on arch_uprobe_analyze_insn() which should validate "vaddr" but
some architectures (csky, s390, and sparc) don't do this.

We can remove the BUG_ON() check in prepare_uprobe() and validate the
offset early in __uprobe_register(). The new IS_ALIGNED() check matches
the alignment check in arch_prepare_kprobe() on supported architectures,
so I think that all insns must be aligned to UPROBE_SWBP_INSN_SIZE.

Another problem is __update_ref_ctr() which was wrong from the very
beginning, it can read/write outside of kmap'ed page unless "vaddr" is
aligned to sizeof(short), __uprobe_register() should check this too.

Reported-by: Linus Torvalds 
Suggested-by: Linus Torvalds 
Signed-off-by: Oleg Nesterov 
Reviewed-by: Srikar Dronamraju 
Acked-by: Christian Borntraeger 
Tested-by: Sven Schnelle 
Cc: Steven Rostedt 
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

kernel/relay.c: handle alloc_percpu returning NULL in relay_open

2020-06-07T11:16:49+00:00

commit 54e200ab40fc14c863bcc80a51e20b7906608fce upstream.

alloc_percpu() may return NULL, which means chan->buf may be set to NULL.
In that case, when we do *per_cpu_ptr(chan->buf, ...), we dereference an
invalid pointer:

  BUG: Unable to handle kernel data access at 0x7dae0000
  Faulting instruction address: 0xc0000000003f3fec
  ...
  NIP relay_open+0x29c/0x600
  LR relay_open+0x270/0x600
  Call Trace:
     relay_open+0x264/0x600 (unreliable)
     __blk_trace_setup+0x254/0x600
     blk_trace_setup+0x68/0xa0
     sg_ioctl+0x7bc/0x2e80
     do_vfs_ioctl+0x13c/0x1300
     ksys_ioctl+0x94/0x130
     sys_ioctl+0x48/0xb0
     system_call+0x5c/0x68

Check if alloc_percpu returns NULL.

This was found by syzkaller both on x86 and powerpc, and the reproducer
it found on powerpc is capable of hitting the issue as an unprivileged
user.

Fixes: 017c59c042d0 ("relay: Use per CPU constructs for the relay channel buffer pointers")
Reported-by: syzbot+1e925b4b836afe85a1c6@syzkaller-ppc64.appspotmail.com
Reported-by: syzbot+587b2421926808309d21@syzkaller-ppc64.appspotmail.com
Reported-by: syzbot+58320b7171734bf79d26@syzkaller.appspotmail.com
Reported-by: syzbot+d6074fb08bdb2e010520@syzkaller.appspotmail.com
Signed-off-by: Daniel Axtens 
Signed-off-by: Andrew Morton 
Reviewed-by: Michael Ellerman 
Reviewed-by: Andrew Donnellan 
Acked-by: David Rientjes 
Cc: Akash Goel 
Cc: Andrew Donnellan 
Cc: Guenter Roeck 
Cc: Salvatore Bonaccorso 
Cc: 	[4.10+]
Link: http://lkml.kernel.org/r/20191219121256.26480-1-dja@axtens.net
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

Revert "cgroup: Add memory barriers to plug cgroup_rstat_updated() race window"

2020-06-07T11:16:44+00:00

[ Upstream commit d8ef4b38cb69d907f9b0e889c44d05fc0f890977 ]

This reverts commit 9a9e97b2f1f2 ("cgroup: Add memory barriers to plug
cgroup_rstat_updated() race window").

The commit was added in anticipation of memcg rstat conversion which needed
synchronous accounting for the event counters (e.g. oom kill count). However,
the conversion didn't get merged due to percpu memory overhead concern which
couldn't be addressed at the time.

Unfortunately, the patch's addition of smp_mb() to cgroup_rstat_updated()
meant that every scheduling event now had to go through an additional full
barrier and Mel Gorman noticed it as 1% regression in netperf UDP_STREAM test.

There's no need to have this barrier in tree now and even if we need
synchronous accounting in the future, the right thing to do is separating that
out to a separate function so that hot paths which don't care about
synchronous behavior don't have to pay the overhead of the full barrier. Let's
revert.

Signed-off-by: Tejun Heo 
Reported-by: Mel Gorman 
Link: http://lkml.kernel.org/r/20200409154413.GK3818@techsingularity.net
Cc: v4.18+
Signed-off-by: Sasha Levin

sched/fair: Fix enqueue_task_fair() warning some more

2020-05-27T15:48:31+00:00

[ Upstream commit b34cb07dde7c2346dec73d053ce926aeaa087303 ]

sched/fair: Fix enqueue_task_fair warning some more

The recent patch, fe61468b2cb (sched/fair: Fix enqueue_task_fair warning)
did not fully resolve the issues with the rq->tmp_alone_branch !=
&rq->leaf_cfs_rq_list warning in enqueue_task_fair. There is a case where
the first for_each_sched_entity loop exits due to on_rq, having incompletely
updated the list.  In this case the second for_each_sched_entity loop can
further modify se. The later code to fix up the list management fails to do
what is needed because se does not point to the sched_entity which broke out
of the first loop. The list is not fixed up because the throttled parent was
already added back to the list by a task enqueue in a parallel child hierarchy.

Address this by calling list_add_leaf_cfs_rq if there are throttled parents
while doing the second for_each_sched_entity loop.

Fixes: fe61468b2cb ("sched/fair: Fix enqueue_task_fair warning")
Suggested-by: Vincent Guittot 
Signed-off-by: Phil Auld 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Dietmar Eggemann 
Reviewed-by: Vincent Guittot 
Link: https://lkml.kernel.org/r/20200512135222.GC2201@lorien.usersys.redhat.com
Signed-off-by: Sasha Levin

sched/fair: Fix reordering of enqueue/dequeue_task_fair()

2020-05-27T15:48:30+00:00

[ Upstream commit 5ab297bab984310267734dfbcc8104566658ebef ]

Even when a cgroup is throttled, the group se of a child cgroup can still
be enqueued and its gse->on_rq stays true. When a task is enqueued on such
child, we still have to update the load_avg and increase
h_nr_running of the throttled cfs. Nevertheless, the 1st
for_each_sched_entity() loop is skipped because of gse->on_rq == true and the
2nd loop because the cfs is throttled whereas we have to update both
load_avg with the old h_nr_running and increase h_nr_running in such case.

The same sequence can happen during dequeue when se moves to parent before
breaking in the 1st loop.

Note that the update of load_avg will effectively happen only once in order
to sync up to the throttled time. Next call for updating load_avg will stop
early because the clock stays unchanged.

Signed-off-by: Vincent Guittot 
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Ingo Molnar 
Fixes: 6d4d22468dae ("sched/fair: Reorder enqueue/dequeue_task_fair path")
Link: https://lkml.kernel.org/r/20200306084208.12583-1-vincent.guittot@linaro.org
Signed-off-by: Sasha Levin

sched/fair: Reorder enqueue/dequeue_task_fair path

2020-05-27T15:48:30+00:00

[ Upstream commit 6d4d22468dae3d8757af9f8b81b848a76ef4409d ]

The walk through the cgroup hierarchy during the enqueue/dequeue of a task
is split in 2 distinct parts for throttled cfs_rq without any added value
but making code less readable.

Change the code ordering such that everything related to a cfs_rq
(throttled or not) will be done in the same loop.

In addition, the same steps ordering is used when updating a cfs_rq:

 - update_load_avg
 - update_cfs_group
 - update *h_nr_running

This reordering enables the use of h_nr_running in PELT algorithm.

No functional and performance changes are expected and have been noticed
during tests.

Signed-off-by: Vincent Guittot 
Signed-off-by: Mel Gorman 
Signed-off-by: Ingo Molnar 
Reviewed-by: "Dietmar Eggemann "
Acked-by: Peter Zijlstra 
Cc: Juri Lelli 
Cc: Valentin Schneider 
Cc: Phil Auld 
Cc: Hillf Danton 
Link: https://lore.kernel.org/r/20200224095223.13361-5-mgorman@techsingularity.net
Signed-off-by: Sasha Levin

bpf: Prevent mmap()'ing read-only maps as writable

2020-05-27T15:48:30+00:00

[ Upstream commit dfeb376dd4cb2c5004aeb625e2475f58a5ff2ea7 ]

As discussed in [0], it's dangerous to allow mapping BPF map, that's meant to
be frozen and is read-only on BPF program side, because that allows user-space
to actually store a writable view to the page even after it is frozen. This is
exacerbated by BPF verifier making a strong assumption that contents of such
frozen map will remain unchanged. To prevent this, disallow mapping
BPF_F_RDONLY_PROG mmap()'able BPF maps as writable, ever.

  [0] https://lore.kernel.org/bpf/CAEf4BzYGWYhXdp6BJ7_=9OQPJxQpgug080MMjdSB72i9R+5c6g@mail.gmail.com/

Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY")
Suggested-by: Jann Horn 
Signed-off-by: Andrii Nakryiko 
Signed-off-by: Alexei Starovoitov 
Reviewed-by: Jann Horn 
Link: https://lore.kernel.org/bpf/20200519053824.1089415-1-andriin@fb.com
Signed-off-by: Sasha Levin

bpf: Add bpf_probe_read_{user, kernel}_str() to do_refine_retval_range

2020-05-27T15:48:15+00:00

commit 47cc0ed574abcbbde0cf143ddb21a0baed1aa2df upstream.

Given bpf_probe_read{,str}() BPF helpers are now only available under
CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE, we need to add the drop-in
replacements of bpf_probe_read_{kernel,user}_str() to do_refine_retval_range()
as well to avoid hitting the same issue as in 849fa50662fbc ("bpf/verifier:
refine retval R0 state for bpf_get_stack helper").

Signed-off-by: Daniel Borkmann 
Signed-off-by: Alexei Starovoitov 
Acked-by: John Fastabend 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20200515101118.6508-3-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman

bpf: Restrict bpf_probe_read{, str}() only to archs where they work

2020-05-27T15:48:14+00:00

commit 0ebeea8ca8a4d1d453ad299aef0507dab04f6e8d upstream.

Given the legacy bpf_probe_read{,str}() BPF helpers are broken on archs
with overlapping address ranges, we should really take the next step to
disable them from BPF use there.

To generally fix the situation, we've recently added new helper variants
bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str().
For details on them, see 6ae08ae3dea2 ("bpf: Add probe_read_{user, kernel}
and probe_read_{user,kernel}_str helpers").

Given bpf_probe_read{,str}() have been around for ~5 years by now, there
are plenty of users at least on x86 still relying on them today, so we
cannot remove them entirely w/o breaking the BPF tracing ecosystem.

However, their use should be restricted to archs with non-overlapping
address ranges where they are working in their current form. Therefore,
move this behind a CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE and
have x86, arm64, arm select it (other archs supporting it can follow-up
on it as well).

For the remaining archs, they can workaround easily by relying on the
feature probe from bpftool which spills out defines that can be used out
of BPF C code to implement the drop-in replacement for old/new kernels
via: bpftool feature probe macro

Suggested-by: Linus Torvalds 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Alexei Starovoitov 
Reviewed-by: Masami Hiramatsu 
Acked-by: Linus Torvalds 
Cc: Brendan Gregg 
Cc: Christoph Hellwig 
Link: https://lore.kernel.org/bpf/20200515101118.6508-2-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman

bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier

2020-05-20T06:22:38+00:00

commit b2a5212fb634561bb734c6356904e37f6665b955 upstream.

Usage of plain %s conversion specifier in bpf_trace_printk() suffers from the
very same issue as bpf_probe_read{,str}() helpers, that is, it is broken on
archs with overlapping address ranges.

While the helpers have been addressed through work in 6ae08ae3dea2 ("bpf: Add
probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers"), we need
an option for bpf_trace_printk() as well to fix it.

Similarly as with the helpers, force users to make an explicit choice by adding
%pks and %pus specifier to bpf_trace_printk() which will then pick the corresponding
strncpy_from_unsafe*() variant to perform the access under KERNEL_DS or USER_DS.
The %pk* (kernel specifier) and %pu* (user specifier) can later also be extended
for other objects aside strings that are probed and printed under tracing, and
reused out of other facilities like bpf_seq_printf() or BTF based type printing.

Existing behavior of %s for current users is still kept working for archs where it
is not broken and therefore gated through CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.
For archs not having this property we fall-back to pick probing under KERNEL_DS as
a sensible default.

Fixes: 8d3b7dce8622 ("bpf: add support for %s specifier to bpf_trace_printk()")
Reported-by: Linus Torvalds 
Reported-by: Christoph Hellwig 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Alexei Starovoitov 
Cc: Masami Hiramatsu 
Cc: Brendan Gregg 
Link: https://lore.kernel.org/bpf/20200515101118.6508-4-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman