The patch titled
Subject: device_cgroup: fix unchecked cgroup parent usage
has been added to the -mm tree. Its filename is
device_cgroup-fix-unchecked-cgroup-parent-usage.patch
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From: Aristeu Rozanski <aris@xxxxxxxxxx>
Subject: device_cgroup: fix unchecked cgroup parent usage
In 4cef7299b478687 ("device_cgroup: add proper checking when changing
default behavior") 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.
Signed-off-by: Aristeu Rozanski <aris@xxxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
Acked-by: Serge E. Hallyn <serge.hallyn@xxxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
security/device_cgroup.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff -puN security/device_cgroup.c~device_cgroup-fix-unchecked-cgroup-parent-usage security/device_cgroup.c
--- a/security/device_cgroup.c~device_cgroup-fix-unchecked-cgroup-parent-usage
+++ a/security/device_cgroup.c
@@ -352,6 +352,8 @@ static int parent_has_perm(struct dev_cg
*/
static inline int may_allow_all(struct dev_cgroup *parent)
{
+ if (!parent)
+ return 1;
return parent->behavior == DEVCG_DEFAULT_ALLOW;
}
@@ -376,11 +378,14 @@ static int devcgroup_update_access(struc
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 @@ static int devcgroup_update_access(struc
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);
_
Patches currently in -mm which might be from aris@xxxxxxxxxx are
fanotify-fix-missing-break.patch
device_cgroup-fix-unchecked-cgroup-parent-usage.patch
linux-next.patch
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