linux-stable.git/kernel/cgroup/cgroup.c, branch v5.10.78

cgroup: Fix memory leak caused by missing cgroup_bpf_offline

2021-11-02T18:48:21+00:00

commit 04f8ef5643bcd8bcde25dfdebef998aea480b2ba upstream.

When enabling CONFIG_CGROUP_BPF, kmemleak can be observed by running
the command as below:

    $mount -t cgroup -o none,name=foo cgroup cgroup/
    $umount cgroup/

unreferenced object 0xc3585c40 (size 64):
  comm "mount", pid 425, jiffies 4294959825 (age 31.990s)
  hex dump (first 32 bytes):
    01 00 00 80 84 8c 28 c0 00 00 00 00 00 00 00 00  ......(.........
    00 00 00 00 00 00 00 00 6c 43 a0 c3 00 00 00 00  ........lC......
  backtrace:
    [] cgroup_bpf_inherit+0x44/0x24c
    [<1f03679c>] cgroup_setup_root+0x174/0x37c
    [] cgroup1_get_tree+0x2c0/0x4a0
    [] vfs_get_tree+0x24/0x108
    [] path_mount+0x384/0x988
    [] do_mount+0x64/0x9c
    [<208c9cfe>] sys_mount+0xfc/0x1f4
    [<06dd06e0>] ret_fast_syscall+0x0/0x48
    [] 0xbeb4daa8

This is because that since the commit 2b0d3d3e4fcf ("percpu_ref: reduce
memory footprint of percpu_ref in fast path") root_cgrp->bpf.refcnt.data
is allocated by the function percpu_ref_init in cgroup_bpf_inherit which
is called by cgroup_setup_root when mounting, but not freed along with
root_cgrp when umounting. Adding cgroup_bpf_offline which calls
percpu_ref_kill to cgroup_kill_sb can free root_cgrp->bpf.refcnt.data in
umount path.

This patch also fixes the commit 4bfc0bb2c60e ("bpf: decouple the lifetime
of cgroup_bpf from cgroup itself"). A cgroup_bpf_offline is needed to do a
cleanup that frees the resources which are allocated by cgroup_bpf_inherit
in cgroup_setup_root.

And inside cgroup_bpf_offline, cgroup_get() is at the beginning and
cgroup_put is at the end of cgroup_bpf_release which is called by
cgroup_bpf_offline. So cgroup_bpf_offline can keep the balance of
cgroup's refcount.

Fixes: 2b0d3d3e4fcf ("percpu_ref: reduce memory footprint of percpu_ref in fast path")
Fixes: 4bfc0bb2c60e ("bpf: decouple the lifetime of cgroup_bpf from cgroup itself")
Signed-off-by: Quanyang Wang 
Signed-off-by: Alexei Starovoitov 
Acked-by: Roman Gushchin 
Acked-by: John Fastabend 
Link: https://lore.kernel.org/bpf/20211018075623.26884-1-quanyang.wang@windriver.com
Signed-off-by: Greg Kroah-Hartman

cgroup: disable controllers at parse time

2021-06-16T10:01:36+00:00

[ Upstream commit 45e1ba40837ac2f6f4d4716bddb8d44bd7e4a251 ]

This patch effectively reverts the commit a3e72739b7a7 ("cgroup: fix
too early usage of static_branch_disable()"). The commit 6041186a3258
("init: initialize jump labels before command line option parsing") has
moved the jump_label_init() before parse_args() which has made the
commit a3e72739b7a7 unnecessary. On the other hand there are
consequences of disabling the controllers later as there are subsystems
doing the controller checks for different decisions. One such incident
is reported [1] regarding the memory controller and its impact on memory
reclaim code.

[1] https://lore.kernel.org/linux-mm/921e53f3-4b13-aab8-4a9e-e83ff15371e4@nec.com

Signed-off-by: Shakeel Butt 
Reported-by: NOMURA JUNICHI(野村　淳一) 
Signed-off-by: Tejun Heo 
Tested-by: Jun'ichi Nomura 
Signed-off-by: Sasha Levin

cgroup: fix psi monitor for root cgroup

2021-02-17T10:02:21+00:00

commit 385aac1519417b89cb91b77c22e4ca21db563cd0 upstream.

Fix NULL pointer dereference when adding new psi monitor to the root
cgroup. PSI files for root cgroup was introduced in df5ba5be742 by using
system wide psi struct when reading, but file write/monitor was not
properly fixed. Since the PSI config for the root cgroup isn't
initialized, the current implementation tries to lock a NULL ptr,
resulting in a crash.

Can be triggered by running this as root:
$ tee /sys/fs/cgroup/cpu.pressure <<< "some 10000 1000000"

Signed-off-by: Odin Ugedal 
Reviewed-by: Suren Baghdasaryan 
Acked-by: Dan Schatzberg 
Fixes: df5ba5be7425 ("kernel/sched/psi.c: expose pressure metrics on root cgroup")
Acked-by: Johannes Weiner 
Cc: stable@vger.kernel.org # 5.2+
Signed-off-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

cgroup: Zero sized write should be no-op

2020-09-30T17:52:06+00:00

Do not report failure on zero sized writes, and handle them as no-op.

There's issues for example in case of writev() when there's iovec
containing zero buffer as a first one. It's expected writev() on below
example to successfully perform the write to specified writable cgroup
file expecting integer value, and to return 2. For now it's returning
value -1, and skipping the write:

	int writetest(int fd) {
	  const char *buf1 = "";
	  const char *buf2 = "1\n";
          struct iovec iov[2] = {
                { .iov_base = (void*)buf1, .iov_len = 0 },
                { .iov_base = (void*)buf2, .iov_len = 2 }
          };
	  return writev(fd, iov, 2);
	}

This patch fixes the issue by checking if there's nothing to write,
and handling the write as no-op by just returning 0.

Signed-off-by: Jouni Roivas 
Signed-off-by: Tejun Heo

cgroup: remove redundant kernfs_activate in cgroup_setup_root()

2020-09-30T16:03:10+00:00

This step is already done in rebind_subsystems().

Not necessary to do it again.

Signed-off-by: Wei Yang 
Signed-off-by: Tejun Heo

cgroup: fix cgroup_sk_alloc() for sk_clone_lock()

2020-07-07T20:34:11+00:00

When we clone a socket in sk_clone_lock(), its sk_cgrp_data is
copied, so the cgroup refcnt must be taken too. And, unlike the
sk_alloc() path, sock_update_netprioidx() is not called here.
Therefore, it is safe and necessary to grab the cgroup refcnt
even when cgroup_sk_alloc is disabled.

sk_clone_lock() is in BH context anyway, the in_interrupt()
would terminate this function if called there. And for sk_alloc()
skcd->val is always zero. So it's safe to factor out the code
to make it more readable.

The global variable 'cgroup_sk_alloc_disabled' is used to determine
whether to take these reference counts. It is impossible to make
the reference counting correct unless we save this bit of information
in skcd->val. So, add a new bit there to record whether the socket
has already taken the reference counts. This obviously relies on
kmalloc() to align cgroup pointers to at least 4 bytes,
ARCH_KMALLOC_MINALIGN is certainly larger than that.

This bug seems to be introduced since the beginning, commit
d979a39d7242 ("cgroup: duplicate cgroup reference when cloning sockets")
tried to fix it but not compeletely. It seems not easy to trigger until
the recent commit 090e28b229af
("netprio_cgroup: Fix unlimited memory leak of v2 cgroups") was merged.

Fixes: bd1060a1d671 ("sock, cgroup: add sock->sk_cgroup")
Reported-by: Cameron Berkenpas 
Reported-by: Peter Geis 
Reported-by: Lu Fengqi 
Reported-by: Daniël Sonck 
Reported-by: Zhang Qiang 
Tested-by: Cameron Berkenpas 
Tested-by: Peter Geis 
Tested-by: Thomas Lamprecht 
Cc: Daniel Borkmann 
Cc: Zefan Li 
Cc: Tejun Heo 
Cc: Roman Gushchin 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller

Merge branch 'for-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2020-06-06T16:59:34+00:00

Pull cgroup updates from Tejun Heo:
 "Just two patches: one to add system-level cpu.stat to the root cgroup
  for convenience and a trivial comment update"

* 'for-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: add cpu.stat file to root cgroup
  cgroup: Remove stale comments

cgroup: add cpu.stat file to root cgroup

2020-05-28T14:06:35+00:00

Currently, the root cgroup does not have a cpu.stat file. Add one which
is consistent with /proc/stat to capture global cpu statistics that
might not fall under cgroup accounting.

We haven't done this in the past because the data are already presented
in /proc/stat and we didn't want to add overhead from collecting root
cgroup stats when cgroups are configured, but no cgroups have been
created.

By keeping the data consistent with /proc/stat, I think we avoid the
first problem, while improving the usability of cgroups stats.
We avoid the second problem by computing the contents of cpu.stat from
existing data collected for /proc/stat anyway.

Signed-off-by: Boris Burkov 
Suggested-by: Tejun Heo 
Signed-off-by: Tejun Heo

cgroup: Remove stale comments

2020-05-26T17:20:24+00:00

- The default root is where we can create v2 cgroups.
- The __DEVEL__sane_behavior mount option has been removed long long ago.

Signed-off-by: Li Zefan 
Signed-off-by: Tejun Heo

bpf: Refactor bpf_link update handling

2020-04-29T00:27:07+00:00

Make bpf_link update support more generic by making it into another
bpf_link_ops methods. This allows generic syscall handling code to be agnostic
to various conditionally compiled features (e.g., the case of
CONFIG_CGROUP_BPF). This also allows to keep link type-specific code to remain
static within respective code base. Refactor existing bpf_cgroup_link code and
take advantage of this.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20200429001614.1544-2-andriin@fb.com