Author: kevans
Date: Tue Dec 8 18:47:22 2020
New Revision: 368462
URL: https://svnweb.freebsd.org/changeset/base/368462
Log:
cpuset_set{affinity,domain}: do not allow empty masks
cpuset_modify() would not currently catch this, because it only checks that
the new mask is a subset of the root set and circumvents the EDEADLK check
in cpuset_testupdate().
This change both directly validates the mask coming in since we can
trivially detect an empty mask, and it updates cpuset_testupdate to catch
stuff like this going forward by always ensuring we don't end up with an
empty mask.
The check_mask argument has been renamed because the 'check' verbiage does
not imply to me that it's actually doing a different operation. We're either
augmenting the existing mask, or we are replacing it entirely.
Reported by: syzbot+4e3b1009de98d2fabcda at syzkaller.appspotmail.com
Discussed with: andrew
Reviewed by: andrew, markj
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D27511
Modified:
head/sys/kern/kern_cpuset.c
Modified: head/sys/kern/kern_cpuset.c
==============================================================================
--- head/sys/kern/kern_cpuset.c Tue Dec 8 18:45:47 2020 (r368461)
+++ head/sys/kern/kern_cpuset.c Tue Dec 8 18:47:22 2020 (r368462)
@@ -633,7 +633,7 @@ domainset_shadow(const struct domainset *pdomain,
* empty as well as RDONLY flags.
*/
static int
-cpuset_testupdate(struct cpuset *set, cpuset_t *mask, int check_mask)
+cpuset_testupdate(struct cpuset *set, cpuset_t *mask, int augment_mask)
{
struct cpuset *nset;
cpuset_t newmask;
@@ -642,13 +642,14 @@ cpuset_testupdate(struct cpuset *set, cpuset_t *mask,
mtx_assert(&cpuset_lock, MA_OWNED);
if (set->cs_flags & CPU_SET_RDONLY)
return (EPERM);
- if (check_mask) {
- if (!CPU_OVERLAP(&set->cs_mask, mask))
- return (EDEADLK);
+ if (augment_mask) {
CPU_COPY(&set->cs_mask, &newmask);
CPU_AND(&newmask, mask);
} else
CPU_COPY(mask, &newmask);
+
+ if (CPU_EMPTY(&newmask))
+ return (EDEADLK);
error = 0;
LIST_FOREACH(nset, &set->cs_children, cs_siblings)
if ((error = cpuset_testupdate(nset, &newmask, 1)) != 0)
@@ -723,7 +724,7 @@ out:
*/
static int
cpuset_testupdate_domain(struct cpuset *set, struct domainset *dset,
- struct domainset *orig, int *count, int check_mask)
+ struct domainset *orig, int *count, int augment_mask __unused)
{
struct cpuset *nset;
struct domainset *domain;
@@ -2001,6 +2002,10 @@ kern_cpuset_setaffinity(struct thread *td, cpulevel_t
goto out;
}
}
+ if (CPU_EMPTY(mask)) {
+ error = EDEADLK;
+ goto out;
+ }
switch (level) {
case CPU_LEVEL_ROOT:
case CPU_LEVEL_CPUSET:
@@ -2254,6 +2259,10 @@ kern_cpuset_setdomain(struct thread *td, cpulevel_t le
error = EINVAL;
goto out;
}
+ }
+ if (DOMAINSET_EMPTY(mask)) {
+ error = EDEADLK;
+ goto out;
}
DOMAINSET_COPY(mask, &domain.ds_mask);
domain.ds_policy = policy;