linux-stable.git/kernel, branch v5.4.93

bpf: Fix helper bpf_map_peek_elem_proto pointing to wrong callback

2021-01-23T14:57:56+00:00

commit 301a33d51880619d0c5a581b5a48d3a5248fa84b upstream.

I assume this was obtained by copy/paste. Point it to bpf_map_peek_elem()
instead of bpf_map_pop_elem(). In practice it may have been less likely
hit when under JIT given shielded via 84430d4232c3 ("bpf, verifier: avoid
retpoline for map push/pop/peek operation").

Fixes: f1a2e44a3aec ("bpf: add queue and stack maps")
Signed-off-by: Mircea Cirjaliu 
Signed-off-by: Daniel Borkmann 
Cc: Mauricio Vasquez 
Link: https://lore.kernel.org/bpf/AM7PR02MB6082663DFDCCE8DA7A6DD6B1BBA30@AM7PR02MB6082.eurprd02.prod.outlook.com
Signed-off-by: Greg Kroah-Hartman

bpf: Don't leak memory in bpf getsockopt when optlen == 0

2021-01-23T14:57:56+00:00

commit 4be34f3d0731b38a1b24566b37fbb39500aaf3a2 upstream.

optlen == 0 indicates that the kernel should ignore BPF buffer
and use the original one from the user. We, however, forget
to free the temporary buffer that we've allocated for BPF.

Fixes: d8fe449a9c51 ("bpf: Don't return EINVAL from {get,set}sockopt when optlen > PAGE_SIZE")
Reported-by: Martin KaFai Lau 
Signed-off-by: Stanislav Fomichev 
Signed-off-by: Daniel Borkmann 
Acked-by: Martin KaFai Lau 
Link: https://lore.kernel.org/bpf/20210112162829.775079-1-sdf@google.com
Signed-off-by: Greg Kroah-Hartman

elfcore: fix building with clang

2021-01-23T14:57:55+00:00

commit 6e7b64b9dd6d96537d816ea07ec26b7dedd397b9 upstream.

kernel/elfcore.c only contains weak symbols, which triggers a bug with
clang in combination with recordmcount:

  Cannot find symbol for section 2: .text.
  kernel/elfcore.o: failed

Move the empty stubs into linux/elfcore.h as inline functions.  As only
two architectures use these, just use the architecture specific Kconfig
symbols to key off the declaration.

Link: https://lkml.kernel.org/r/20201204165742.3815221-2-arnd@kernel.org
Signed-off-by: Arnd Bergmann 
Cc: Nathan Chancellor 
Cc: Nick Desaulniers 
Cc: Barret Rhoden 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Cc: Jian Cai 
Signed-off-by: Greg Kroah-Hartman

tracing/kprobes: Do the notrace functions check without kprobes on ftrace

2021-01-19T17:26:12+00:00

commit 7bb83f6fc4ee84e95d0ac0d14452c2619fb3fe70 upstream.

Enable the notrace function check on the architecture which doesn't
support kprobes on ftrace but support dynamic ftrace. This notrace
function check is not only for the kprobes on ftrace but also
sw-breakpoint based kprobes.
Thus there is no reason to limit this check for the arch which
supports kprobes on ftrace.

This also changes the dependency of Kconfig. Because kprobe event
uses the function tracer's address list for identifying notrace
function, if the CONFIG_DYNAMIC_FTRACE=n, it can not check whether
the target function is notrace or not.

Link: https://lkml.kernel.org/r/20210105065730.2634785-1-naveen.n.rao@linux.vnet.ibm.com
Link: https://lkml.kernel.org/r/161007957862.114704.4512260007555399463.stgit@devnote2

Cc: stable@vger.kernel.org
Fixes: 45408c4f92506 ("tracing: kprobes: Prohibit probing on notrace function")
Acked-by: Naveen N. Rao 
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

workqueue: Kick a worker based on the actual activation of delayed works

2021-01-12T19:16:09+00:00

[ Upstream commit 01341fbd0d8d4e717fc1231cdffe00343088ce0b ]

In realtime scenario, We do not want to have interference on the
isolated cpu cores. but when invoking alloc_workqueue() for percpu wq
on the housekeeping cpu, it kick a kworker on the isolated cpu.

  alloc_workqueue
    pwq_adjust_max_active
      wake_up_worker

The comment in pwq_adjust_max_active() said:
  "Need to kick a worker after thawed or an unbound wq's
   max_active is bumped"

So it is unnecessary to kick a kworker for percpu's wq when invoking
alloc_workqueue(). this patch only kick a worker based on the actual
activation of delayed works.

Signed-off-by: Yunfeng Ye 
Reviewed-by: Lai Jiangshan 
Signed-off-by: Tejun Heo 
Signed-off-by: Sasha Levin

exec: Transform exec_update_mutex into a rw_semaphore

2021-01-09T12:44:55+00:00

[ Upstream commit f7cfd871ae0c5008d94b6f66834e7845caa93c15 ]

Recently syzbot reported[0] that there is a deadlock amongst the users
of exec_update_mutex.  The problematic lock ordering found by lockdep
was:

   perf_event_open  (exec_update_mutex -> ovl_i_mutex)
   chown            (ovl_i_mutex       -> sb_writes)
   sendfile         (sb_writes         -> p->lock)
     by reading from a proc file and writing to overlayfs
   proc_pid_syscall (p->lock           -> exec_update_mutex)

While looking at possible solutions it occured to me that all of the
users and possible users involved only wanted to state of the given
process to remain the same.  They are all readers.  The only writer is
exec.

There is no reason for readers to block on each other.  So fix
this deadlock by transforming exec_update_mutex into a rw_semaphore
named exec_update_lock that only exec takes for writing.

Cc: Jann Horn 
Cc: Vasiliy Kulikov 
Cc: Al Viro 
Cc: Bernd Edlinger 
Cc: Oleg Nesterov 
Cc: Christopher Yeoh 
Cc: Cyrill Gorcunov 
Cc: Sargun Dhillon 
Cc: Christian Brauner 
Cc: Arnd Bergmann 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Arnaldo Carvalho de Melo 
Fixes: eea9673250db ("exec: Add exec_update_mutex to replace cred_guard_mutex")
[0] https://lkml.kernel.org/r/00000000000063640c05ade8e3de@google.com
Reported-by: syzbot+db9cdf3dd1f64252c6ef@syzkaller.appspotmail.com
Link: https://lkml.kernel.org/r/87ft4mbqen.fsf@x220.int.ebiederm.org
Signed-off-by: Eric W. Biederman 
Signed-off-by: Sasha Levin

rwsem: Implement down_read_interruptible

2021-01-09T12:44:55+00:00

[ Upstream commit 31784cff7ee073b34d6eddabb95e3be2880a425c ]

In preparation for converting exec_update_mutex to a rwsem so that
multiple readers can execute in parallel and not deadlock, add
down_read_interruptible.  This is needed for perf_event_open to be
converted (with no semantic changes) from working on a mutex to
wroking on a rwsem.

Signed-off-by: Eric W. Biederman 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/87k0tybqfy.fsf@x220.int.ebiederm.org
Signed-off-by: Sasha Levin

rwsem: Implement down_read_killable_nested

2021-01-09T12:44:55+00:00

[ Upstream commit 0f9368b5bf6db0c04afc5454b1be79022a681615 ]

In preparation for converting exec_update_mutex to a rwsem so that
multiple readers can execute in parallel and not deadlock, add
down_read_killable_nested.  This is needed so that kcmp_lock
can be converted from working on a mutexes to working on rw_semaphores.

Signed-off-by: Eric W. Biederman 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/87o8jabqh3.fsf@x220.int.ebiederm.org
Signed-off-by: Sasha Levin

perf: Break deadlock involving exec_update_mutex

2021-01-09T12:44:54+00:00

[ Upstream commit 78af4dc949daaa37b3fcd5f348f373085b4e858f ]

Syzbot reported a lock inversion involving perf. The sore point being
perf holding exec_update_mutex() for a very long time, specifically
across a whole bunch of filesystem ops in pmu::event_init() (uprobes)
and anon_inode_getfile().

This then inverts against procfs code trying to take
exec_update_mutex.

Move the permission checks later, such that we need to hold the mutex
over less code.

Reported-by: syzbot+db9cdf3dd1f64252c6ef@syzkaller.appspotmail.com
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Sasha Levin

tick/sched: Remove bogus boot "safety" check

2021-01-06T13:48:40+00:00

[ Upstream commit ba8ea8e7dd6e1662e34e730eadfc52aa6816f9dd ]

can_stop_idle_tick() checks whether the do_timer() duty has been taken over
by a CPU on boot. That's silly because the boot CPU always takes over with
the initial clockevent device.

But even if no CPU would have installed a clockevent and taken over the
duty then the question whether the tick on the current CPU can be stopped
or not is moot. In that case the current CPU would have no clockevent
either, so there would be nothing to keep ticking.

Remove it.

Signed-off-by: Thomas Gleixner 
Acked-by: Frederic Weisbecker 
Link: https://lore.kernel.org/r/20201206212002.725238293@linutronix.de
Signed-off-by: Sasha Levin