linux.git, branch v5.4.189

Linux 5.4.189

2022-04-15T12:18:42+00:00

Link: https://lore.kernel.org/r/20220414110855.141582785@linuxfoundation.org
Tested-by: Guenter Roeck 
Tested-by: Hulk Robot 
Tested-by: Shuah Khan 
Signed-off-by: Greg Kroah-Hartman

ACPI: processor idle: Check for architectural support for LPI

2022-04-15T12:18:41+00:00

commit eb087f305919ee8169ad65665610313e74260463 upstream.

When `osc_pc_lpi_support_confirmed` is set through `_OSC` and `_LPI` is
populated then the cpuidle driver assumes that LPI is fully functional.

However currently the kernel only provides architectural support for LPI
on ARM.  This leads to high power consumption on X86 platforms that
otherwise try to enable LPI.

So probe whether or not LPI support is implemented before enabling LPI in
the kernel.  This is done by overloading `acpi_processor_ffh_lpi_probe` to
check whether it returns `-EOPNOTSUPP`. It also means that all future
implementations of `acpi_processor_ffh_lpi_probe` will need to follow
these semantics as well.

Reviewed-by: Sudeep Holla 
Signed-off-by: Mario Limonciello 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

cpuidle: PSCI: Move the `has_lpi` check to the beginning of the function

2022-04-15T12:18:41+00:00

commit 01f6c7338ce267959975da65d86ba34f44d54220 upstream.

Currently the first thing checked is whether the PCSI cpu_suspend function
has been initialized.

Another change will be overloading `acpi_processor_ffh_lpi_probe` and
calling it sooner.  So make the `has_lpi` check the first thing checked
to prepare for that change.

Reviewed-by: Sudeep Holla 
Signed-off-by: Mario Limonciello 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

selftests: cgroup: Test open-time cgroup namespace usage for migration checks

2022-04-15T12:18:41+00:00

commit bf35a7879f1dfb0d050fe779168bcf25c7de66f5 upstream.

When a task is writing to an fd opened by a different task, the perm check
should use the cgroup namespace of the latter task. Add a test for it.

Tested-by: Michal Koutný 
Signed-off-by: Tejun Heo 
[OP: backport to v5.4: adjust context, add wait.h and fcntl.h includes]
Signed-off-by: Ovidiu Panait 
Signed-off-by: Greg Kroah-Hartman

selftests: cgroup: Test open-time credential usage for migration checks

2022-04-15T12:18:41+00:00

commit 613e040e4dc285367bff0f8f75ea59839bc10947 upstream.

When a task is writing to an fd opened by a different task, the perm check
should use the credentials of the latter task. Add a test for it.

Tested-by: Michal Koutný 
Signed-off-by: Tejun Heo 
[OP: backport to v5.4: adjust context]
Signed-off-by: Ovidiu Panait 
Signed-off-by: Greg Kroah-Hartman

selftests: cgroup: Make cg_create() use 0755 for permission instead of 0644

2022-04-15T12:18:41+00:00

commit b09c2baa56347ae65795350dfcc633dedb1c2970 upstream.

0644 is an odd perm to create a cgroup which is a directory. Use the regular
0755 instead. This is necessary for euid switching test case.

Reviewed-by: Michal Koutný 
Signed-off-by: Tejun Heo 
Signed-off-by: Ovidiu Panait 
Signed-off-by: Greg Kroah-Hartman

cgroup: Use open-time cgroup namespace for process migration perm checks

2022-04-15T12:18:41+00:00

commit e57457641613fef0d147ede8bd6a3047df588b95 upstream.

cgroup process migration permission checks are performed at write time as
whether a given operation is allowed or not is dependent on the content of
the write - the PID. This currently uses current's cgroup namespace which is
a potential security weakness as it may allow scenarios where a less
privileged process tricks a more privileged one into writing into a fd that
it created.

This patch makes cgroup remember the cgroup namespace at the time of open
and uses it for migration permission checks instad of current's. Note that
this only applies to cgroup2 as cgroup1 doesn't have namespace support.

This also fixes a use-after-free bug on cgroupns reported in

 https://lore.kernel.org/r/00000000000048c15c05d0083397@google.com

Note that backporting this fix also requires the preceding patch.

Reported-by: "Eric W. Biederman" 
Suggested-by: Linus Torvalds 
Cc: Michal Koutný 
Cc: Oleg Nesterov 
Reviewed-by: Michal Koutný 
Reported-by: syzbot+50f5cf33a284ce738b62@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/00000000000048c15c05d0083397@google.com
Fixes: 5136f6365ce3 ("cgroup: implement "nsdelegate" mount option")
Signed-off-by: Tejun Heo 
[mkoutny: v5.10: duplicate ns check in procs/threads write handler, adjust context]
Signed-off-by: Michal Koutný 
Signed-off-by: Greg Kroah-Hartman 
[OP: backport to v5.4: drop changes to cgroup_attach_permissions() and
cgroup_css_set_fork(), adjust cgroup_procs_write_permission() calls]
Signed-off-by: Ovidiu Panait 
Signed-off-by: Greg Kroah-Hartman

cgroup: Allocate cgroup_file_ctx for kernfs_open_file->priv

2022-04-15T12:18:41+00:00

commit 0d2b5955b36250a9428c832664f2079cbf723bec upstream.

of->priv is currently used by each interface file implementation to store
private information. This patch collects the current two private data usages
into struct cgroup_file_ctx which is allocated and freed by the common path.
This allows generic private data which applies to multiple files, which will
be used to in the following patch.

Note that cgroup_procs iterator is now embedded as procs.iter in the new
cgroup_file_ctx so that it doesn't need to be allocated and freed
separately.

v2: union dropped from cgroup_file_ctx and the procs iterator is embedded in
    cgroup_file_ctx as suggested by Linus.

v3: Michal pointed out that cgroup1's procs pidlist uses of->priv too.
    Converted. Didn't change to embedded allocation as cgroup1 pidlists get
    stored for caching.

Signed-off-by: Tejun Heo 
Cc: Linus Torvalds 
Reviewed-by: Michal Koutný 
[mkoutny: v5.10: modify cgroup.pressure handlers, adjust context]
Signed-off-by: Michal Koutný 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Ovidiu Panait 
Signed-off-by: Greg Kroah-Hartman

cgroup: Use open-time credentials for process migraton perm checks

2022-04-15T12:18:41+00:00

commit 1756d7994ad85c2479af6ae5a9750b92324685af upstream.

cgroup process migration permission checks are performed at write time as
whether a given operation is allowed or not is dependent on the content of
the write - the PID. This currently uses current's credentials which is a
potential security weakness as it may allow scenarios where a less
privileged process tricks a more privileged one into writing into a fd that
it created.

This patch makes both cgroup2 and cgroup1 process migration interfaces to
use the credentials saved at the time of open (file->f_cred) instead of
current's.

Reported-by: "Eric W. Biederman" 
Suggested-by: Linus Torvalds 
Fixes: 187fe84067bd ("cgroup: require write perm on common ancestor when moving processes on the default hierarchy")
Reviewed-by: Michal Koutný 
Signed-off-by: Tejun Heo 
[OP: backport to 5.4: apply original __cgroup_procs_write() changes to
cgroup_threads_write() and cgroup_procs_write()]
Signed-off-by: Ovidiu Panait 
Signed-off-by: Greg Kroah-Hartman

io_uring: fix fs->users overflow

2022-04-15T12:18:41+00:00

There is a bunch of cases where we can grab req->fs but not put it, this
can be used to cause a controllable overflow with further implications.
Release req->fs in the request free path and make sure we zero the field
to be sure we don't do it twice.

Fixes: cac68d12c531 ("io_uring: grab ->fs as part of async offload")
Reported-by: Bing-Jhong Billy Jheng 
Signed-off-by: Pavel Begunkov 
Signed-off-by: Greg Kroah-Hartman