Messages in this thread Patch in this message | | | Date | Wed, 31 Oct 2012 12:04:30 -0400 | From | Aristeu Rozanski <> | Subject | [PATCH] device_cgroup: fix unchecked cgroup parent usage |
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In 4cef7299b4786879a3e113e84084a72b24590c5b the cgroup parent usage is unchecked. root will not have a parent and trying to use device.{allow,deny} will cause problems. For some reason my stressing scripts didn't test the root directory so I didn't catch it on my regular tests.
Andrew, Tejun, this patch needs to make Linus tree ASAP or a revert for 4cef7299b4786879a3e113e84084a72b24590c5b.
Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Tejun Heo <tj@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Cc: James Morris <jmorris@namei.org> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Serge Hallyn <serge.hallyn@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Aristeu Rozanski <aris@redhat.com>
--- github.orig/security/device_cgroup.c 2012-10-26 17:18:01.739366780 -0400 +++ github/security/device_cgroup.c 2012-10-29 10:03:33.221918003 -0400 @@ -352,6 +352,8 @@ */ static inline int may_allow_all(struct dev_cgroup *parent) { + if (!parent) + return 1; return parent->behavior == DEVCG_DEFAULT_ALLOW; } @@ -376,11 +378,14 @@ int count, rc; struct dev_exception_item ex; struct cgroup *p = devcgroup->css.cgroup; - struct dev_cgroup *parent = cgroup_to_devcgroup(p->parent); + struct dev_cgroup *parent = NULL; if (!capable(CAP_SYS_ADMIN)) return -EPERM; + if (p->parent) + parent = cgroup_to_devcgroup(p->parent); + memset(&ex, 0, sizeof(ex)); b = buffer; @@ -391,11 +396,14 @@ if (!may_allow_all(parent)) return -EPERM; dev_exception_clean(devcgroup); + devcgroup->behavior = DEVCG_DEFAULT_ALLOW; + if (!parent) + break; + rc = dev_exceptions_copy(&devcgroup->exceptions, &parent->exceptions); if (rc) return rc; - devcgroup->behavior = DEVCG_DEFAULT_ALLOW; break; case DEVCG_DENY: dev_exception_clean(devcgroup);
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