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-rw-r--r--block/ioprio.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/block/ioprio.c b/block/ioprio.c
index 0e4ff245f2bf..6f01d35a5145 100644
--- a/block/ioprio.c
+++ b/block/ioprio.c
@@ -69,7 +69,14 @@ int ioprio_check_cap(int ioprio)
switch (class) {
case IOPRIO_CLASS_RT:
- if (!capable(CAP_SYS_NICE) && !capable(CAP_SYS_ADMIN))
+ /*
+ * Originally this only checked for CAP_SYS_ADMIN,
+ * which was implicitly allowed for pid 0 by security
+ * modules such as SELinux. Make sure we check
+ * CAP_SYS_ADMIN first to avoid a denial/avc for
+ * possibly missing CAP_SYS_NICE permission.
+ */
+ if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_NICE))
return -EPERM;
fallthrough;
/* rt has prio field too */
@@ -213,6 +220,7 @@ SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
pgrp = task_pgrp(current);
else
pgrp = find_vpid(who);
+ read_lock(&tasklist_lock);
do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
tmpio = get_task_ioprio(p);
if (tmpio < 0)
@@ -222,6 +230,8 @@ SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
else
ret = ioprio_best(ret, tmpio);
} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
+ read_unlock(&tasklist_lock);
+
break;
case IOPRIO_WHO_USER:
uid = make_kuid(current_user_ns(), who);