linux-toradex.git/kernel/cgroup, branch v5.14-rc5

cgroup1: fix leaked context root causing sporadic NULL deref in LTP

2021-07-21T16:39:20+00:00

Richard reported sporadic (roughly one in 10 or so) null dereferences and
other strange behaviour for a set of automated LTP tests.  Things like:

   BUG: kernel NULL pointer dereference, address: 0000000000000008
   #PF: supervisor read access in kernel mode
   #PF: error_code(0x0000) - not-present page
   PGD 0 P4D 0
   Oops: 0000 [#1] PREEMPT SMP PTI
   CPU: 0 PID: 1516 Comm: umount Not tainted 5.10.0-yocto-standard #1
   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
   RIP: 0010:kernfs_sop_show_path+0x1b/0x60

...or these others:

   RIP: 0010:do_mkdirat+0x6a/0xf0
   RIP: 0010:d_alloc_parallel+0x98/0x510
   RIP: 0010:do_readlinkat+0x86/0x120

There were other less common instances of some kind of a general scribble
but the common theme was mount and cgroup and a dubious dentry triggering
the NULL dereference.  I was only able to reproduce it under qemu by
replicating Richard's setup as closely as possible - I never did get it
to happen on bare metal, even while keeping everything else the same.

In commit 71d883c37e8d ("cgroup_do_mount(): massage calling conventions")
we see this as a part of the overall change:

   --------------
           struct cgroup_subsys *ss;
   -       struct dentry *dentry;

   [...]

   -       dentry = cgroup_do_mount(&cgroup_fs_type, fc->sb_flags, root,
   -                                CGROUP_SUPER_MAGIC, ns);

   [...]

   -       if (percpu_ref_is_dying(&root->cgrp.self.refcnt)) {
   -               struct super_block *sb = dentry->d_sb;
   -               dput(dentry);
   +       ret = cgroup_do_mount(fc, CGROUP_SUPER_MAGIC, ns);
   +       if (!ret && percpu_ref_is_dying(&root->cgrp.self.refcnt)) {
   +               struct super_block *sb = fc->root->d_sb;
   +               dput(fc->root);
                   deactivate_locked_super(sb);
                   msleep(10);
                   return restart_syscall();
           }
   --------------

In changing from the local "*dentry" variable to using fc->root, we now
export/leave that dentry pointer in the file context after doing the dput()
in the unlikely "is_dying" case.   With LTP doing a crazy amount of back to
back mount/unmount [testcases/bin/cgroup_regression_5_1.sh] the unlikely
becomes slightly likely and then bad things happen.

A fix would be to not leave the stale reference in fc->root as follows:

   --------------
                  dput(fc->root);
  +               fc->root = NULL;
                  deactivate_locked_super(sb);
   --------------

...but then we are just open-coding a duplicate of fc_drop_locked() so we
simply use that instead.

Cc: Al Viro 
Cc: Tejun Heo 
Cc: Zefan Li 
Cc: Johannes Weiner 
Cc: stable@vger.kernel.org      # v5.1+
Reported-by: Richard Purdie 
Fixes: 71d883c37e8d ("cgroup_do_mount(): massage calling conventions")
Signed-off-by: Paul Gortmaker 
Signed-off-by: Tejun Heo

fs: add vfs_parse_fs_param_source() helper

2021-07-14T16:19:06+00:00

Add a simple helper that filesystems can use in their parameter parser
to parse the "source" parameter. A few places open-coded this function
and that already caused a bug in the cgroup v1 parser that we fixed.
Let's make it harder to get this wrong by introducing a helper which
performs all necessary checks.

Link: https://syzkaller.appspot.com/bug?id=6312526aba5beae046fdae8f00399f87aab48b12
Cc: Christoph Hellwig 
Cc: Alexander Viro 
Cc: Dmitry Vyukov 
Signed-off-by: Christian Brauner 
Signed-off-by: Linus Torvalds

cgroup: verify that source is a string

2021-07-14T16:19:06+00:00

The following sequence can be used to trigger a UAF:

    int fscontext_fd = fsopen("cgroup");
    int fd_null = open("/dev/null, O_RDONLY);
    int fsconfig(fscontext_fd, FSCONFIG_SET_FD, "source", fd_null);
    close_range(3, ~0U, 0);

The cgroup v1 specific fs parser expects a string for the "source"
parameter.  However, it is perfectly legitimate to e.g.  specify a file
descriptor for the "source" parameter.  The fs parser doesn't know what
a filesystem allows there.  So it's a bug to assume that "source" is
always of type fs_value_is_string when it can reasonably also be
fs_value_is_file.

This assumption in the cgroup code causes a UAF because struct
fs_parameter uses a union for the actual value.  Access to that union is
guarded by the param->type member.  Since the cgroup paramter parser
didn't check param->type but unconditionally moved param->string into
fc->source a close on the fscontext_fd would trigger a UAF during
put_fs_context() which frees fc->source thereby freeing the file stashed
in param->file causing a UAF during a close of the fd_null.

Fix this by verifying that param->type is actually a string and report
an error if not.

In follow up patches I'll add a new generic helper that can be used here
and by other filesystems instead of this error-prone copy-pasta fix.
But fixing it in here first makes backporting a it to stable a lot
easier.

Fixes: 8d2451f4994f ("cgroup1: switch to option-by-option parsing")
Reported-by: syzbot+283ce5a46486d6acdbaf@syzkaller.appspotmail.com
Cc: Christoph Hellwig 
Cc: Alexander Viro 
Cc: Dmitry Vyukov 
Cc: 
Cc: syzkaller-bugs 
Signed-off-by: Christian Brauner 
Signed-off-by: Linus Torvalds

Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

2021-07-02T22:14:36+00:00

Pull SCSI updates from James Bottomley:
 "This series consists of the usual driver updates (ufs, ibmvfc,
  megaraid_sas, lpfc, elx, mpi3mr, qedi, iscsi, storvsc, mpt3sas) with
  elx and mpi3mr being new drivers.

  The major core change is a rework to drop the status byte handling
  macros and the old bit shifted definitions and the rest of the updates
  are minor fixes"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (287 commits)
  scsi: aha1740: Avoid over-read of sense buffer
  scsi: arcmsr: Avoid over-read of sense buffer
  scsi: ips: Avoid over-read of sense buffer
  scsi: ufs: ufs-mediatek: Add missing of_node_put() in ufs_mtk_probe()
  scsi: elx: libefc: Fix IRQ restore in efc_domain_dispatch_frame()
  scsi: elx: libefc: Fix less than zero comparison of a unsigned int
  scsi: elx: efct: Fix pointer error checking in debugfs init
  scsi: elx: efct: Fix is_originator return code type
  scsi: elx: efct: Fix link error for _bad_cmpxchg
  scsi: elx: efct: Eliminate unnecessary boolean check in efct_hw_command_cancel()
  scsi: elx: efct: Do not use id uninitialized in efct_lio_setup_session()
  scsi: elx: efct: Fix error handling in efct_hw_init()
  scsi: elx: efct: Remove redundant initialization of variable lun
  scsi: elx: efct: Fix spelling mistake "Unexected" -> "Unexpected"
  scsi: lpfc: Fix build error in lpfc_scsi.c
  scsi: target: iscsi: Remove redundant continue statement
  scsi: qla4xxx: Remove redundant continue statement
  scsi: ppa: Switch to use module_parport_driver()
  scsi: imm: Switch to use module_parport_driver()
  scsi: mpt3sas: Fix error return value in _scsih_expander_add()
  ...

Merge branch 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2021-07-02T00:22:14+00:00

Pull cgroup updates from Tejun Heo:

 - cgroup.kill is added which implements atomic killing of the whole
   subtree.

   Down the line, this should be able to replace the multiple userland
   implementations of "keep killing till empty".

 - PSI can now be turned off at boot time to avoid overhead for
   configurations which don't care about PSI.

* 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: make per-cgroup pressure stall tracking configurable
  cgroup: Fix kernel-doc
  cgroup: inline cgroup_task_freeze()
  tests/cgroup: test cgroup.kill
  tests/cgroup: move cg_wait_for(), cg_prepare_for_wait()
  tests/cgroup: use cgroup.kill in cg_killall()
  docs/cgroup: add entry for cgroup.kill
  cgroup: introduce cgroup.kill

Merge branch 'akpm' (patches from Andrew)

2021-06-30T00:29:11+00:00

Merge misc updates from Andrew Morton:
 "191 patches.

  Subsystems affected by this patch series: kthread, ia64, scripts,
  ntfs, squashfs, ocfs2, kernel/watchdog, and mm (gup, pagealloc, slab,
  slub, kmemleak, dax, debug, pagecache, gup, swap, memcg, pagemap,
  mprotect, bootmem, dma, tracing, vmalloc, kasan, initialization,
  pagealloc, and memory-failure)"

* emailed patches from Andrew Morton : (191 commits)
  mm,hwpoison: make get_hwpoison_page() call get_any_page()
  mm,hwpoison: send SIGBUS with error virutal address
  mm/page_alloc: split pcp->high across all online CPUs for cpuless nodes
  mm/page_alloc: allow high-order pages to be stored on the per-cpu lists
  mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM
  mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA
  docs: remove description of DISCONTIGMEM
  arch, mm: remove stale mentions of DISCONIGMEM
  mm: remove CONFIG_DISCONTIGMEM
  m68k: remove support for DISCONTIGMEM
  arc: remove support for DISCONTIGMEM
  arc: update comment about HIGHMEM implementation
  alpha: remove DISCONTIGMEM and NUMA
  mm/page_alloc: move free_the_page
  mm/page_alloc: fix counting of managed_pages
  mm/page_alloc: improve memmap_pages dbg msg
  mm: drop SECTION_SHIFT in code comments
  mm/page_alloc: introduce vm.percpu_pagelist_high_fraction
  mm/page_alloc: limit the number of pages on PCP lists when reclaim is active
  mm/page_alloc: scale the number of pages that are batch freed
  ...

loop: charge i/o to mem and blk cg

2021-06-29T17:53:50+00:00

The current code only associates with the existing blkcg when aio is used
to access the backing file.  This patch covers all types of i/o to the
backing file and also associates the memcg so if the backing file is on
tmpfs, memory is charged appropriately.

This patch also exports cgroup_get_e_css and int_active_memcg so it can be
used by the loop module.

Link: https://lkml.kernel.org/r/20210610173944.1203706-4-schatzberg.dan@gmail.com
Signed-off-by: Dan Schatzberg 
Acked-by: Johannes Weiner 
Acked-by: Jens Axboe 
Cc: Chris Down 
Cc: Michal Hocko 
Cc: Ming Lei 
Cc: Shakeel Butt 
Cc: Tejun Heo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sched: Change task_struct::state

2021-06-18T09:43:09+00:00

Change the type and name of task_struct::state. Drop the volatile and
shrink it to an 'unsigned int'. Rename it in order to find all uses
such that we can use READ_ONCE/WRITE_ONCE as appropriate.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Daniel Bristot de Oliveira 
Acked-by: Will Deacon 
Acked-by: Daniel Thompson 
Link: https://lore.kernel.org/r/20210611082838.550736351@infradead.org

scsi: cgroup: Add cgroup_get_from_id()

2021-06-10T14:01:31+00:00

Add a new function, cgroup_get_from_id(), to retrieve the cgroup associated
with a cgroup id. Also export the function cgroup_get_e_css() as this is
needed in blk-cgroup.h.

Link: https://lore.kernel.org/r/20210608043556.274139-2-muneendra.kumar@broadcom.com
Reviewed-by: Himanshu Madhani 
Reviewed-by: Hannes Reinecke 
Acked-by: Tejun Heo 
Signed-off-by: Muneendra Kumar 
Signed-off-by: Martin K. Petersen

cgroup1: don't allow '\n' in renaming

2021-06-10T13:58:50+00:00

cgroup_mkdir() have restriction on newline usage in names:
$ mkdir $'/sys/fs/cgroup/cpu/test\ntest2'
mkdir: cannot create directory
'/sys/fs/cgroup/cpu/test\ntest2': Invalid argument

But in cgroup1_rename() such check is missed.
This allows us to make /proc//cgroup unparsable:
$ mkdir /sys/fs/cgroup/cpu/test
$ mv /sys/fs/cgroup/cpu/test $'/sys/fs/cgroup/cpu/test\ntest2'
$ echo $$ > $'/sys/fs/cgroup/cpu/test\ntest2'
$ cat /proc/self/cgroup
11:pids:/
10:freezer:/
9:hugetlb:/
8:cpuset:/
7:blkio:/user.slice
6:memory:/user.slice
5:net_cls,net_prio:/
4:perf_event:/
3:devices:/user.slice
2:cpu,cpuacct:/test
test2
1:name=systemd:/
0::/

Signed-off-by: Alexander Kuznetsov 
Reported-by: Andrey Krasichkov 
Acked-by: Dmitry Yakunin 
Cc: stable@vger.kernel.org
Signed-off-by: Tejun Heo