linux-stable.git/kernel, branch v4.19.322

rtmutex: Drop rt_mutex::wait_lock before scheduling

2024-09-12T09:02:55+00:00

commit d33d26036a0274b472299d7dcdaa5fb34329f91b upstream.

rt_mutex_handle_deadlock() is called with rt_mutex::wait_lock held.  In the
good case it returns with the lock held and in the deadlock case it emits a
warning and goes into an endless scheduling loop with the lock held, which
triggers the 'scheduling in atomic' warning.

Unlock rt_mutex::wait_lock in the dead lock case before issuing the warning
and dropping into the schedule for ever loop.

[ tglx: Moved unlock before the WARN(), removed the pointless comment,
  	massaged changelog, added Fixes tag ]

Fixes: 3d5c9340d194 ("rtmutex: Handle deadlock detection smarter")
Signed-off-by: Roland Xu 
Signed-off-by: Thomas Gleixner 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/ME0P300MB063599BEF0743B8FA339C2CECC802@ME0P300MB0635.AUSP300.PROD.OUTLOOK.COM
Signed-off-by: Greg Kroah-Hartman

tracing: Avoid possible softlockup in tracing_iter_reset()

2024-09-12T09:02:55+00:00

[ Upstream commit 49aa8a1f4d6800721c7971ed383078257f12e8f9 ]

In __tracing_open(), when max latency tracers took place on the cpu,
the time start of its buffer would be updated, then event entries with
timestamps being earlier than start of the buffer would be skipped
(see tracing_iter_reset()).

Softlockup will occur if the kernel is non-preemptible and too many
entries were skipped in the loop that reset every cpu buffer, so add
cond_resched() to avoid it.

Cc: stable@vger.kernel.org
Fixes: 2f26ebd549b9a ("tracing: use timestamp to determine start of latency traces")
Link: https://lore.kernel.org/20240827124654.3817443-1-zhengyejian@huaweicloud.com
Suggested-by: Steven Rostedt 
Signed-off-by: Zheng Yejian 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Sasha Levin

ring-buffer: Rename ring_buffer_read() to read_buffer_iter_advance()

2024-09-12T09:02:55+00:00

[ Upstream commit bc1a72afdc4a91844928831cac85731566e03bc6 ]

When the ring buffer was first created, the iterator followed the normal
producer/consumer operations where it had both a peek() operation, that just
returned the event at the current location, and a read(), that would return
the event at the current location and also increment the iterator such that
the next peek() or read() will return the next event.

The only use of the ring_buffer_read() is currently to move the iterator to
the next location and nothing now actually reads the event it returns.
Rename this function to its actual use case to ring_buffer_iter_advance(),
which also adds the "iter" part to the name, which is more meaningful. As
the timestamp returned by ring_buffer_read() was never used, there's no
reason that this new version should bother having returning it. It will also
become a void function.

Link: http://lkml.kernel.org/r/20200317213416.018928618@goodmis.org

Signed-off-by: Steven Rostedt (VMware) 
Stable-dep-of: 49aa8a1f4d68 ("tracing: Avoid possible softlockup in tracing_iter_reset()")
Signed-off-by: Sasha Levin

uprobes: Use kzalloc to allocate xol area

2024-09-12T09:02:54+00:00

commit e240b0fde52f33670d1336697c22d90a4fe33c84 upstream.

To prevent unitialized members, use kzalloc to allocate
the xol area.

Fixes: b059a453b1cf1 ("x86/vdso: Add mremap hook to vm_special_mapping")
Signed-off-by: Sven Schnelle 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Oleg Nesterov 
Link: https://lore.kernel.org/r/20240903102313.3402529-1-svens@linux.ibm.com
Signed-off-by: Greg Kroah-Hartman

smp: Add missing destroy_work_on_stack() call in smp_call_on_cpu()

2024-09-12T09:02:53+00:00

[ Upstream commit 77aeb1b685f9db73d276bad4bb30d48505a6fd23 ]

For CONFIG_DEBUG_OBJECTS_WORK=y kernels sscs.work defined by
INIT_WORK_ONSTACK() is initialized by debug_object_init_on_stack() for
the debug check in __init_work() to work correctly.

But this lacks the counterpart to remove the tracked object from debug
objects again, which will cause a debug object warning once the stack is
freed.

Add the missing destroy_work_on_stack() invocation to cure that.

[ tglx: Massaged changelog ]

Signed-off-by: Zqiang 
Signed-off-by: Thomas Gleixner 
Tested-by: Paul E. McKenney 
Link: https://lore.kernel.org/r/20240704065213.13559-1-qiang.zhang1211@gmail.com
Signed-off-by: Sasha Levin

cgroup: Protect css->cgroup write under css_set_lock

2024-09-12T09:02:53+00:00

[ Upstream commit 57b56d16800e8961278ecff0dc755d46c4575092 ]

The writing of css->cgroup associated with the cgroup root in
rebind_subsystems() is currently protected only by cgroup_mutex.
However, the reading of css->cgroup in both proc_cpuset_show() and
proc_cgroup_show() is protected just by css_set_lock. That makes the
readers susceptible to racing problems like data tearing or caching.
It is also a problem that can be reported by KCSAN.

This can be fixed by using READ_ONCE() and WRITE_ONCE() to access
css->cgroup. Alternatively, the writing of css->cgroup can be moved
under css_set_lock as well which is done by this patch.

Signed-off-by: Waiman Long 
Signed-off-by: Tejun Heo 
Signed-off-by: Sasha Levin

cgroup/cpuset: Prevent UAF in proc_cpuset_show()

2024-09-04T11:13:07+00:00

commit 1be59c97c83ccd67a519d8a49486b3a8a73ca28a upstream.

An UAF can happen when /proc/cpuset is read as reported in [1].

This can be reproduced by the following methods:
1.add an mdelay(1000) before acquiring the cgroup_lock In the
 cgroup_path_ns function.
2.$cat /proc//cpuset   repeatly.
3.$mount -t cgroup -o cpuset cpuset /sys/fs/cgroup/cpuset/
$umount /sys/fs/cgroup/cpuset/   repeatly.

The race that cause this bug can be shown as below:

(umount)		|	(cat /proc//cpuset)
css_release		|	proc_cpuset_show
css_release_work_fn	|	css = task_get_css(tsk, cpuset_cgrp_id);
css_free_rwork_fn	|	cgroup_path_ns(css->cgroup, ...);
cgroup_destroy_root	|	mutex_lock(&cgroup_mutex);
rebind_subsystems	|
cgroup_free_root 	|
			|	// cgrp was freed, UAF
			|	cgroup_path_ns_locked(cgrp,..);

When the cpuset is initialized, the root node top_cpuset.css.cgrp
will point to &cgrp_dfl_root.cgrp. In cgroup v1, the mount operation will
allocate cgroup_root, and top_cpuset.css.cgrp will point to the allocated
&cgroup_root.cgrp. When the umount operation is executed,
top_cpuset.css.cgrp will be rebound to &cgrp_dfl_root.cgrp.

The problem is that when rebinding to cgrp_dfl_root, there are cases
where the cgroup_root allocated by setting up the root for cgroup v1
is cached. This could lead to a Use-After-Free (UAF) if it is
subsequently freed. The descendant cgroups of cgroup v1 can only be
freed after the css is released. However, the css of the root will never
be released, yet the cgroup_root should be freed when it is unmounted.
This means that obtaining a reference to the css of the root does
not guarantee that css.cgrp->root will not be freed.

Fix this problem by using rcu_read_lock in proc_cpuset_show().
As cgroup_root is kfree_rcu after commit d23b5c577715
("cgroup: Make operations on the cgroup root_list RCU safe"),
css->cgroup won't be freed during the critical section.
To call cgroup_path_ns_locked, css_set_lock is needed, so it is safe to
replace task_get_css with task_css.

[1] https://syzkaller.appspot.com/bug?extid=9b1ff7be974a403aa4cd

Fixes: a79a908fd2b0 ("cgroup: introduce cgroup namespaces")
Signed-off-by: Chen Ridong 
Signed-off-by: Tejun Heo 
Signed-off-by: Shivani Agarwal 
Signed-off-by: Greg Kroah-Hartman

hrtimer: Prevent queuing of hrtimer without a function callback

2024-09-04T11:13:04+00:00

[ Upstream commit 5a830bbce3af16833fe0092dec47b6dd30279825 ]

The hrtimer function callback must not be NULL. It has to be specified by
the call side but it is not validated by the hrtimer code. When a hrtimer
is queued without a function callback, the kernel crashes with a null
pointer dereference when trying to execute the callback in __run_hrtimer().

Introduce a validation before queuing the hrtimer in
hrtimer_start_range_ns().

[anna-maria: Rephrase commit message]

Signed-off-by: Phil Chang 
Signed-off-by: Anna-Maria Behnsen 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Anna-Maria Behnsen 
Signed-off-by: Sasha Levin

tracing: Fix overflow in get_free_elt()

2024-08-19T03:32:16+00:00

commit bcf86c01ca4676316557dd482c8416ece8c2e143 upstream.

"tracing_map->next_elt" in get_free_elt() is at risk of overflowing.

Once it overflows, new elements can still be inserted into the tracing_map
even though the maximum number of elements (`max_elts`) has been reached.
Continuing to insert elements after the overflow could result in the
tracing_map containing "tracing_map->max_size" elements, leaving no empty
entries.
If any attempt is made to insert an element into a full tracing_map using
`__tracing_map_insert()`, it will cause an infinite loop with preemption
disabled, leading to a CPU hang problem.

Fix this by preventing any further increments to "tracing_map->next_elt"
once it reaches "tracing_map->max_elt".

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu 
Fixes: 08d43a5fa063e ("tracing: Add lock-free tracing_map")
Co-developed-by: Cheng-Jui Wang 
Link: https://lore.kernel.org/20240805055922.6277-1-Tze-nan.Wu@mediatek.com
Signed-off-by: Cheng-Jui Wang 
Signed-off-by: Tze-nan Wu 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

ntp: Safeguard against time_constant overflow

2024-08-19T03:32:16+00:00

commit 06c03c8edce333b9ad9c6b207d93d3a5ae7c10c0 upstream.

Using syzkaller with the recently reintroduced signed integer overflow
sanitizer produces this UBSAN report:

UBSAN: signed-integer-overflow in ../kernel/time/ntp.c:738:18
9223372036854775806 + 4 cannot be represented in type 'long'
Call Trace:
 handle_overflow+0x171/0x1b0
 __do_adjtimex+0x1236/0x1440
 do_adjtimex+0x2be/0x740

The user supplied time_constant value is incremented by four and then
clamped to the operating range.

Before commit eea83d896e31 ("ntp: NTP4 user space bits update") the user
supplied value was sanity checked to be in the operating range. That change
removed the sanity check and relied on clamping after incrementing which
does not work correctly when the user supplied value is in the overflow
zone of the '+ 4' operation.

The operation requires CAP_SYS_TIME and the side effect of the overflow is
NTP getting out of sync.

Similar to the fixups for time_maxerror and time_esterror, clamp the user
space supplied value to the operating range.

[ tglx: Switch to clamping ]

Fixes: eea83d896e31 ("ntp: NTP4 user space bits update")
Signed-off-by: Justin Stitt 
Signed-off-by: Thomas Gleixner 
Cc: Miroslav Lichvar 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240517-b4-sio-ntp-c-v2-1-f3a80096f36f@google.com
Closes: https://github.com/KSPP/linux/issues/352
Signed-off-by: Greg Kroah-Hartman