linux-stable.git/kernel, branch v4.4.181

kernel/signal.c: trace_signal_deliver when signal_group_exit

2019-06-11T10:24:10+00:00

commit 98af37d624ed8c83f1953b1b6b2f6866011fc064 upstream.

In the fixes commit, removing SIGKILL from each thread signal mask and
executing "goto fatal" directly will skip the call to
"trace_signal_deliver".  At this point, the delivery tracking of the
SIGKILL signal will be inaccurate.

Therefore, we need to add trace_signal_deliver before "goto fatal" after
executing sigdelset.

Note: SEND_SIG_NOINFO matches the fact that SIGKILL doesn't have any info.

Link: http://lkml.kernel.org/r/20190425025812.91424-1-weizhenliang@huawei.com
Fixes: cf43a757fd4944 ("signal: Restore the stop PTRACE_EVENT_EXIT")
Signed-off-by: Zhenliang Wei 
Reviewed-by: Christian Brauner 
Reviewed-by: Oleg Nesterov 
Cc: Eric W. Biederman 
Cc: Ivan Delalande 
Cc: Arnd Bergmann 
Cc: Thomas Gleixner 
Cc: Deepa Dinamani 
Cc: Greg Kroah-Hartman 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

rcutorture: Fix cleanup path for invalid torture_type strings

2019-06-11T10:24:04+00:00

[ Upstream commit b813afae7ab6a5e91b4e16cc567331d9c2ae1f04 ]

If the specified rcutorture.torture_type is not in the rcu_torture_init()
function's torture_ops[] array, rcutorture prints some console messages
and then invokes rcu_torture_cleanup() to set state so that a future
torture test can run.  However, rcu_torture_cleanup() also attempts to
end the test that didn't actually start, and in doing so relies on the
value of cur_ops, a value that is not particularly relevant in this case.
This can result in confusing output or even follow-on failures due to
attempts to use facilities that have not been properly initialized.

This commit therefore sets the value of cur_ops to NULL in this case
and inserts a check near the beginning of rcu_torture_cleanup(),
thus avoiding relying on an irrelevant cur_ops value.

Reported-by: kernel test robot 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Sasha Levin

sched/core: Handle overflow in cpu_shares_write_u64

2019-06-11T10:23:58+00:00

[ Upstream commit 5b61d50ab4ef590f5e1d4df15cd2cea5f5715308 ]

Bit shift in scale_load() could overflow shares. This patch saturates
it to MAX_SHARES like following sched_group_set_shares().

Example:

 # echo 9223372036854776832 > cpu.shares
 # cat cpu.shares

Before patch: 1024
After pattch: 262144

Signed-off-by: Konstantin Khlebnikov 
Acked-by: Peter Zijlstra 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/155125501891.293431.3345233332801109696.stgit@buzz
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

sched/core: Check quota and period overflow at usec to nsec conversion

2019-06-11T10:23:58+00:00

[ Upstream commit 1a8b4540db732ca16c9e43ac7c08b1b8f0b252d8 ]

Large values could overflow u64 and pass following sanity checks.

 # echo 18446744073750000 > cpu.cfs_period_us
 # cat cpu.cfs_period_us
 40448

 # echo 18446744073750000 > cpu.cfs_quota_us
 # cat cpu.cfs_quota_us
 40448

After this patch they will fail with -EINVAL.

Signed-off-by: Konstantin Khlebnikov 
Acked-by: Peter Zijlstra 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/155125502079.293431.3947497929372138600.stgit@buzz
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

audit: fix a memory leak bug

2019-06-11T10:23:58+00:00

[ Upstream commit 70c4cf17e445264453bc5323db3e50aa0ac9e81f ]

In audit_rule_change(), audit_data_to_entry() is firstly invoked to
translate the payload data to the kernel's rule representation. In
audit_data_to_entry(), depending on the audit field type, an audit tree may
be created in audit_make_tree(), which eventually invokes kmalloc() to
allocate the tree.  Since this tree is a temporary tree, it will be then
freed in the following execution, e.g., audit_add_rule() if the message
type is AUDIT_ADD_RULE or audit_del_rule() if the message type is
AUDIT_DEL_RULE. However, if the message type is neither AUDIT_ADD_RULE nor
AUDIT_DEL_RULE, i.e., the default case of the switch statement, this
temporary tree is not freed.

To fix this issue, only allocate the tree when the type is AUDIT_ADD_RULE
or AUDIT_DEL_RULE.

Signed-off-by: Wenwen Wang 
Reviewed-by: Richard Guy Briggs 
Signed-off-by: Paul Moore 
Signed-off-by: Sasha Levin

tracing: Fix partial reading of trace event's id file

2019-06-11T10:23:46+00:00

commit cbe08bcbbe787315c425dde284dcb715cfbf3f39 upstream.

When reading only part of the id file, the ppos isn't tracked correctly.
This is taken care by simple_read_from_buffer.

Reading a single byte, and then the next byte would result EOF.

While this seems like not a big deal, this breaks abstractions that
reads information from files unbuffered. See for example
https://github.com/golang/go/issues/29399

This code was mentioned as problematic in
commit cd458ba9d5a5
("tracing: Do not (ab)use trace_seq in event_id_read()")

An example C code that show this bug is:

  #include 
  #include 

  #include 
  #include 
  #include 
  #include 

  int main(int argc, char **argv) {
    if (argc < 2)
      return 1;
    int fd = open(argv[1], O_RDONLY);
    char c;
    read(fd, &c, 1);
    printf("First  %c\n", c);
    read(fd, &c, 1);
    printf("Second %c\n", c);
  }

Then run with, e.g.

  sudo ./a.out /sys/kernel/debug/tracing/events/tcp/tcp_set_state/id

You'll notice you're getting the first character twice, instead of the
first two characters in the id file.

Link: http://lkml.kernel.org/r/20181231115837.4932-1-elazar@lightbitslabs.com

Cc: Orit Wasserman 
Cc: Oleg Nesterov 
Cc: Ingo Molnar 
Cc: stable@vger.kernel.org
Fixes: 23725aeeab10b ("ftrace: provide an id file for each event")
Signed-off-by: Elazar Leibovich 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

cpu/speculation: Add 'mitigations=' cmdline option

2019-05-16T17:45:15+00:00

commit 98af8452945c55652de68536afdde3b520fec429 upstream.

Keeping track of the number of mitigations for all the CPU speculation
bugs has become overwhelming for many users.  It's getting more and more
complicated to decide which mitigations are needed for a given
architecture.  Complicating matters is the fact that each arch tends to
have its own custom way to mitigate the same vulnerability.

Most users fall into a few basic categories:

a) they want all mitigations off;

b) they want all reasonable mitigations on, with SMT enabled even if
   it's vulnerable; or

c) they want all reasonable mitigations on, with SMT disabled if
   vulnerable.

Define a set of curated, arch-independent options, each of which is an
aggregation of existing options:

- mitigations=off: Disable all mitigations.

- mitigations=auto: [default] Enable all the default mitigations, but
  leave SMT enabled, even if it's vulnerable.

- mitigations=auto,nosmt: Enable all the default mitigations, disabling
  SMT if needed by a mitigation.

Currently, these options are placeholders which don't actually do
anything.  They will be fleshed out in upcoming patches.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Tested-by: Jiri Kosina  (on x86)
Reviewed-by: Jiri Kosina 
Cc: Borislav Petkov 
Cc: "H . Peter Anvin" 
Cc: Andy Lutomirski 
Cc: Peter Zijlstra 
Cc: Jiri Kosina 
Cc: Waiman Long 
Cc: Andrea Arcangeli 
Cc: Jon Masters 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: linux-s390@vger.kernel.org
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org
Cc: Greg Kroah-Hartman 
Cc: Tyler Hicks 
Cc: Linus Torvalds 
Cc: Randy Dunlap 
Cc: Steven Price 
Cc: Phil Auld 
Link: https://lkml.kernel.org/r/b07a8ef9b7c5055c3a4637c87d07c296d5016fe0.1555085500.git.jpoimboe@redhat.com
[bwh: Backported to 4.4:
 - Drop the auto,nosmt option which we can't support
 - Adjust filename]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

x86/speculation: Rework SMT state change

2019-05-16T17:45:11+00:00

commit a74cfffb03b73d41e08f84c2e5c87dec0ce3db9f upstream.

arch_smt_update() is only called when the sysfs SMT control knob is
changed. This means that when SMT is enabled in the sysfs control knob the
system is considered to have SMT active even if all siblings are offline.

To allow finegrained control of the speculation mitigations, the actual SMT
state is more interesting than the fact that siblings could be enabled.

Rework the code, so arch_smt_update() is invoked from each individual CPU
hotplug function, and simplify the update function while at it.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Andy Lutomirski 
Cc: Linus Torvalds 
Cc: Jiri Kosina 
Cc: Tom Lendacky 
Cc: Josh Poimboeuf 
Cc: Andrea Arcangeli 
Cc: David Woodhouse 
Cc: Tim Chen 
Cc: Andi Kleen 
Cc: Dave Hansen 
Cc: Casey Schaufler 
Cc: Asit Mallick 
Cc: Arjan van de Ven 
Cc: Jon Masters 
Cc: Waiman Long 
Cc: Greg KH 
Cc: Dave Stewart 
Cc: Kees Cook 
Link: https://lkml.kernel.org/r/20181125185004.521974984@linutronix.de
[bwh: Backported to 4.4: adjust context]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

sched: Add sched_smt_active()

2019-05-16T17:45:11+00:00

Add the sched_smt_active() function needed for some x86 speculation
mitigations.  This was introduced upstream by commits 1b568f0aabf2
"sched/core: Optimize SCHED_SMT", ba2591a5993e "sched/smt: Update
sched_smt_present at runtime", c5511d03ec09 "sched/smt: Make
sched_smt_present track topology", and 321a874a7ef8 "sched/smt: Expose
sched_smt_present static key".  The upstream implementation uses the
static_key_{disable,enable}_cpuslocked() functions, which aren't
practical to backport.

Signed-off-by: Ben Hutchings 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Peter Zijlstra (Intel) 
Cc: Konrad Rzeszutek Wilk 
Signed-off-by: Greg Kroah-Hartman

x86/speculation: Apply IBPB more strictly to avoid cross-process data leak

2019-05-16T17:45:09+00:00

commit dbfe2953f63c640463c630746cd5d9de8b2f63ae upstream.

Currently, IBPB is only issued in cases when switching into a non-dumpable
process, the rationale being to protect such 'important and security
sensitive' processess (such as GPG) from data leaking into a different
userspace process via spectre v2.

This is however completely insufficient to provide proper userspace-to-userpace
spectrev2 protection, as any process can poison branch buffers before being
scheduled out, and the newly scheduled process immediately becomes spectrev2
victim.

In order to minimize the performance impact (for usecases that do require
spectrev2 protection), issue the barrier only in cases when switching between
processess where the victim can't be ptraced by the potential attacker (as in
such cases, the attacker doesn't have to bother with branch buffers at all).

[ tglx: Split up PTRACE_MODE_NOACCESS_CHK into PTRACE_MODE_SCHED and
  PTRACE_MODE_IBPB to be able to do ptrace() context tracking reasonably
  fine-grained ]

Fixes: 18bf3c3ea8 ("x86/speculation: Use Indirect Branch Prediction Barrier in context switch")
Originally-by: Tim Chen 
Signed-off-by: Jiri Kosina 
Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra 
Cc: Josh Poimboeuf 
Cc: Andrea Arcangeli 
Cc:  "WoodhouseDavid" 
Cc: Andi Kleen 
Cc:  "SchauflerCasey" 
Link: https://lkml.kernel.org/r/nycvar.YFH.7.76.1809251437340.15880@cbobk.fhfr.pm
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman