Commit e250d91d authored Dec 13, 2018 by Ondrej Mosnacek Committed by Tejun Heo Dec 28, 2018

cgroup: fix parsing empty mount option string



This fixes the case where all mount options specified are consumed by an
LSM and all that's left is an empty string. In this case cgroupfs should
accept the string and not fail.

How to reproduce (with SELinux enabled):

    # umount /sys/fs/cgroup/unified
    # mount -o context=system_u:object_r:cgroup_t:s0 -t cgroup2 cgroup2 /sys/fs/cgroup/unified
    mount: /sys/fs/cgroup/unified: wrong fs type, bad option, bad superblock on cgroup2, missing codepage or helper program, or other error.
    # dmesg | tail -n 1
    [   31.575952] cgroup: cgroup2: unknown option ""

Fixes: 67e9c74b ("cgroup: replace __DEVEL__sane_behavior with cgroup2 fs type")
[NOTE: should apply on top of commit 5136f636 ("cgroup: implement "nsdelegate" mount option"), older versions need manual rebase]
Suggested-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

parent 4d71c6f8

kernel/cgroup/cgroup.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1748,7 +1748,7 @@ static int parse_cgroup_root_flags(char data, unsigned int root_flags)

		*root_flags = 0;

		if (!data)
		if (!data \|\| *data == '\0')
		return 0;

		while ((token = strsep(&data, ",")) != NULL) {

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