[PATCH] ima: fix infinite loop within "ima_match_policy" function.
STALE1823d
From: liqiong <hidden>
Date: 2021-08-19 10:21:11
Also in:
linux-integrity, lkml
Subsystem:
extended verification module (evm), integrity measurement architecture (ima), security subsystem, the rest · Maintainers:
Mimi Zohar, Roberto Sassu, Dmitry Kasatkin, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
When "ima_match_policy" is looping while "ima_update_policy" changs the variable "ima_rules", then "ima_match_policy" may can't exit loop, and kernel keeps printf "rcu_sched detected stall on CPU ...". It occurs at boot phase, systemd-services are being checked within "ima_match_policy,at the same time, the variable "ima_rules" is changed by a service. Signed-off-by: liqiong <redacted> --- security/integrity/ima/ima_policy.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index fd5d46e511f1..7e71e643457c 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c@@ -217,6 +217,7 @@ static LIST_HEAD(ima_default_rules); static LIST_HEAD(ima_policy_rules); static LIST_HEAD(ima_temp_rules); static struct list_head *ima_rules = &ima_default_rules; +static DECLARE_RWSEM(ima_rules_sem); static int ima_policy __initdata;
@@ -666,6 +667,7 @@ int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode, if (template_desc && !*template_desc) *template_desc = ima_template_desc_current(); + down_read(&ima_rules_sem); rcu_read_lock(); list_for_each_entry_rcu(entry, ima_rules, list) {
@@ -702,6 +704,7 @@ int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode, break; } rcu_read_unlock(); + up_read(&ima_rules_sem); return action; }
@@ -919,7 +922,9 @@ void ima_update_policy(void) if (ima_rules != policy) { ima_policy_flag = 0; + down_write(&ima_rules_sem); ima_rules = policy; + up_write(&ima_rules_sem); /* * IMA architecture specific policy rules are specified
--
2.11.0