linux-stable.git/kernel, branch v4.9.239

perf: Fix task_function_call() error handling

2020-10-14T07:48:17+00:00

[ Upstream commit 6d6b8b9f4fceab7266ca03d194f60ec72bd4b654 ]

The error handling introduced by commit:

  2ed6edd33a21 ("perf: Add cond_resched() to task_function_call()")

looses any return value from smp_call_function_single() that is not
{0, -EINVAL}. This is a problem because it will return -EXNIO when the
target CPU is offline. Worse, in that case it'll turn into an infinite
loop.

Fixes: 2ed6edd33a21 ("perf: Add cond_resched() to task_function_call()")
Reported-by: Srikar Dronamraju 
Signed-off-by: Kajol Jain 
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Ingo Molnar 
Reviewed-by: Barret Rhoden 
Tested-by: Srikar Dronamraju 
Link: https://lkml.kernel.org/r/20200827064732.20860-1-kjain@linux.ibm.com
Signed-off-by: Sasha Levin

ftrace: Move RCU is watching check after recursion check

2020-10-14T07:48:15+00:00

commit b40341fad6cc2daa195f8090fd3348f18fff640a upstream.

The first thing that the ftrace function callback helper functions should do
is to check for recursion. Peter Zijlstra found that when
"rcu_is_watching()" had its notrace removed, it caused perf function tracing
to crash. This is because the call of rcu_is_watching() is tested before
function recursion is checked and and if it is traced, it will cause an
infinite recursion loop.

rcu_is_watching() should still stay notrace, but to prevent this should
never had crashed in the first place. The recursion prevention must be the
first thing done in callback functions.

Link: https://lore.kernel.org/r/20200929112541.GM2628@hirez.programming.kicks-ass.net

Cc: stable@vger.kernel.org
Cc: Paul McKenney 
Fixes: c68c0fa293417 ("ftrace: Have ftrace_ops_get_func() handle RCU and PER_CPU flags too")
Acked-by: Peter Zijlstra (Intel) 
Reported-by: Peter Zijlstra (Intel) 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

usermodehelper: reset umask to default before executing user process

2020-10-14T07:48:14+00:00

commit 4013c1496c49615d90d36b9d513eee8e369778e9 upstream.

Kernel threads intentionally do CLONE_FS in order to follow any changes
that 'init' does to set up the root directory (or cwd).

It is admittedly a bit odd, but it avoids the situation where 'init'
does some extensive setup to initialize the system environment, and then
we execute a usermode helper program, and it uses the original FS setup
from boot time that may be very limited and incomplete.

[ Both Al Viro and Eric Biederman point out that 'pivot_root()' will
  follow the root regardless, since it fixes up other users of root (see
  chroot_fs_refs() for details), but overmounting root and doing a
  chroot() would not. ]

However, Vegard Nossum noticed that the CLONE_FS not only means that we
follow the root and current working directories, it also means we share
umask with whatever init changed it to. That wasn't intentional.

Just reset umask to the original default (0022) before actually starting
the usermode helper program.

Reported-by: Vegard Nossum 
Cc: Al Viro 
Acked-by: Eric W. Biederman 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

kprobes: Fix to check probe enabled before disarm_kprobe_ftrace()

2020-10-01T18:40:18+00:00

commit 3031313eb3d549b7ad6f9fbcc52ba04412e3eb9e upstream.

Commit 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at
kprobe_ftrace_handler") fixed one bug but not completely fixed yet.
If we run a kprobe_module.tc of ftracetest, kernel showed a warning
as below.

# ./ftracetest test.d/kprobe/kprobe_module.tc
=== Ftrace unit tests ===
[1] Kprobe dynamic event - probing module
...
[   22.400215] ------------[ cut here ]------------
[   22.400962] Failed to disarm kprobe-ftrace at trace_printk_irq_work+0x0/0x7e [trace_printk] (-2)
[   22.402139] WARNING: CPU: 7 PID: 200 at kernel/kprobes.c:1091 __disarm_kprobe_ftrace.isra.0+0x7e/0xa0
[   22.403358] Modules linked in: trace_printk(-)
[   22.404028] CPU: 7 PID: 200 Comm: rmmod Not tainted 5.9.0-rc2+ #66
[   22.404870] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
[   22.406139] RIP: 0010:__disarm_kprobe_ftrace.isra.0+0x7e/0xa0
[   22.406947] Code: 30 8b 03 eb c9 80 3d e5 09 1f 01 00 75 dc 49 8b 34 24 89 c2 48 c7 c7 a0 c2 05 82 89 45 e4 c6 05 cc 09 1f 01 01 e8 a9 c7 f0 ff <0f> 0b 8b 45 e4 eb b9 89 c6 48 c7 c7 70 c2 05 82 89 45 e4 e8 91 c7
[   22.409544] RSP: 0018:ffffc90000237df0 EFLAGS: 00010286
[   22.410385] RAX: 0000000000000000 RBX: ffffffff83066024 RCX: 0000000000000000
[   22.411434] RDX: 0000000000000001 RSI: ffffffff810de8d3 RDI: ffffffff810de8d3
[   22.412687] RBP: ffffc90000237e10 R08: 0000000000000001 R09: 0000000000000001
[   22.413762] R10: 0000000000000000 R11: 0000000000000001 R12: ffff88807c478640
[   22.414852] R13: ffffffff8235ebc0 R14: ffffffffa00060c0 R15: 0000000000000000
[   22.415941] FS:  00000000019d48c0(0000) GS:ffff88807d7c0000(0000) knlGS:0000000000000000
[   22.417264] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   22.418176] CR2: 00000000005bb7e3 CR3: 0000000078f7a000 CR4: 00000000000006a0
[   22.419309] Call Trace:
[   22.419990]  kill_kprobe+0x94/0x160
[   22.420652]  kprobes_module_callback+0x64/0x230
[   22.421470]  notifier_call_chain+0x4f/0x70
[   22.422184]  blocking_notifier_call_chain+0x49/0x70
[   22.422979]  __x64_sys_delete_module+0x1ac/0x240
[   22.423733]  do_syscall_64+0x38/0x50
[   22.424366]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[   22.425176] RIP: 0033:0x4bb81d
[   22.425741] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e0 ff ff ff f7 d8 64 89 01 48
[   22.428726] RSP: 002b:00007ffc70fef008 EFLAGS: 00000246 ORIG_RAX: 00000000000000b0
[   22.430169] RAX: ffffffffffffffda RBX: 00000000019d48a0 RCX: 00000000004bb81d
[   22.431375] RDX: 0000000000000000 RSI: 0000000000000880 RDI: 00007ffc70fef028
[   22.432543] RBP: 0000000000000880 R08: 00000000ffffffff R09: 00007ffc70fef320
[   22.433692] R10: 0000000000656300 R11: 0000000000000246 R12: 00007ffc70fef028
[   22.434635] R13: 0000000000000000 R14: 0000000000000002 R15: 0000000000000000
[   22.435682] irq event stamp: 1169
[   22.436240] hardirqs last  enabled at (1179): [] console_unlock+0x422/0x580
[   22.437466] hardirqs last disabled at (1188): [] console_unlock+0x7b/0x580
[   22.438608] softirqs last  enabled at (866): [] __do_softirq+0x38e/0x490
[   22.439637] softirqs last disabled at (859): [] asm_call_on_stack+0x12/0x20
[   22.440690] ---[ end trace 1e7ce7e1e4567276 ]---
[   22.472832] trace_kprobe: This probe might be able to register after target module is loaded. Continue.

This is because the kill_kprobe() calls disarm_kprobe_ftrace() even
if the given probe is not enabled. In that case, ftrace_set_filter_ip()
fails because the given probe point is not registered to ftrace.

Fix to check the given (going) probe is enabled before invoking
disarm_kprobe_ftrace().

Link: https://lkml.kernel.org/r/159888672694.1411785.5987998076694782591.stgit@devnote2

Fixes: 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at kprobe_ftrace_handler")
Cc: Ingo Molnar 
Cc: "Naveen N . Rao" 
Cc: Anil S Keshavamurthy 
Cc: David Miller 
Cc: Muchun Song 
Cc: Chengming Zhou 
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

printk: handle blank console arguments passed in.

2020-10-01T18:40:14+00:00

[ Upstream commit 48021f98130880dd74286459a1ef48b5e9bc374f ]

If uboot passes a blank string to console_setup then it results in
a trashed memory. Ultimately, the kernel crashes during freeing up
the memory.

This fix checks if there is a blank parameter being
passed to console_setup from uboot. In case it detects that
the console parameter is blank then it doesn't setup the serial
device and it gracefully exits.

Link: https://lore.kernel.org/r/20200522065306.83-1-shreyas.joshi@biamp.com
Signed-off-by: Shreyas Joshi 
Acked-by: Sergey Senozhatsky 
[pmladek@suse.com: Better format the commit message and code, remove unnecessary brackets.]
Signed-off-by: Petr Mladek 
Signed-off-by: Sasha Levin

tracing: Use address-of operator on section symbols

2020-10-01T18:40:10+00:00

[ Upstream commit bf2cbe044da275021b2de5917240411a19e5c50d ]

Clang warns:

../kernel/trace/trace.c:9335:33: warning: array comparison always
evaluates to true [-Wtautological-compare]
        if (__stop___trace_bprintk_fmt != __start___trace_bprintk_fmt)
                                       ^
1 warning generated.

These are not true arrays, they are linker defined symbols, which are
just addresses. Using the address of operator silences the warning and
does not change the runtime result of the check (tested with some print
statements compiled in with clang + ld.lld and gcc + ld.bfd in QEMU).

Link: http://lkml.kernel.org/r/20200220051011.26113-1-natechancellor@gmail.com

Link: https://github.com/ClangBuiltLinux/linux/issues/893
Suggested-by: Nick Desaulniers 
Signed-off-by: Nathan Chancellor 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Sasha Levin

timekeeping: Prevent 32bit truncation in scale64_check_overflow()

2020-10-01T18:40:09+00:00

[ Upstream commit 4cbbc3a0eeed675449b1a4d080008927121f3da3 ]

While unlikely the divisor in scale64_check_overflow() could be >= 32bit in
scale64_check_overflow(). do_div() truncates the divisor to 32bit at least
on 32bit platforms.

Use div64_u64() instead to avoid the truncation to 32-bit.

[ tglx: Massaged changelog ]

Signed-off-by: Wen Yang 
Signed-off-by: Thomas Gleixner 
Link: https://lkml.kernel.org/r/20200120100523.45656-1-wenyang@linux.alibaba.com
Signed-off-by: Sasha Levin

bpf: Remove recursion prevention from rcu free callback

2020-10-01T18:40:08+00:00

[ Upstream commit 8a37963c7ac9ecb7f86f8ebda020e3f8d6d7b8a0 ]

If an element is freed via RCU then recursion into BPF instrumentation
functions is not a concern. The element is already detached from the map
and the RCU callback does not hold any locks on which a kprobe, perf event
or tracepoint attached BPF program could deadlock.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20200224145643.259118710@linutronix.de
Signed-off-by: Sasha Levin

audit: CONFIG_CHANGE don't log internal bookkeeping as an event

2020-10-01T18:40:07+00:00

[ Upstream commit 70b3eeed49e8190d97139806f6fbaf8964306cdb ]

Common Criteria calls out for any action that modifies the audit trail to
be recorded. That usually is interpreted to mean insertion or removal of
rules. It is not required to log modification of the inode information
since the watch is still in effect. Additionally, if the rule is a never
rule and the underlying file is one they do not want events for, they
get an event for this bookkeeping update against their wishes.

Since no device/inode info is logged at insertion and no device/inode
information is logged on update, there is nothing meaningful being
communicated to the admin by the CONFIG_CHANGE updated_rules event. One
can assume that the rule was not "modified" because it is still watching
the intended target. If the device or inode cannot be resolved, then
audit_panic is called which is sufficient.

The correct resolution is to drop logging config_update events since
the watch is still in effect but just on another unknown inode.

Signed-off-by: Steve Grubb 
Signed-off-by: Paul Moore 
Signed-off-by: Sasha Levin

tracing: Set kernel_stack's caller size properly

2020-10-01T18:40:05+00:00

[ Upstream commit cbc3b92ce037f5e7536f6db157d185cd8b8f615c ]

I noticed when trying to use the trace-cmd python interface that reading the raw
buffer wasn't working for kernel_stack events.  This is because it uses a
stubbed version of __dynamic_array that doesn't do the __data_loc trick and
encode the length of the array into the field.  Instead it just shows up as a
size of 0.  So change this to __array and set the len to FTRACE_STACK_ENTRIES
since this is what we actually do in practice and matches how user_stack_trace
works.

Link: http://lkml.kernel.org/r/1411589652-1318-1-git-send-email-jbacik@fb.com

Signed-off-by: Josef Bacik 
[ Pulled from the archeological digging of my INBOX ]
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Sasha Levin