The audit_filter_rules() function in auditsc.c used the in_[e]group_p()
functions to check GID/EGID match, but these functions use the current
task's credentials, while the comparison should use the credentials of
the task given to audit_filter_rules() as a parameter (tsk).

Note that we can use group_search(cred->group_info, ...) as a
replacement for both in_group_p and in_egroup_p as these functions only
compare the parameter to cred->fsgid/egid and then call group_search.

In fact, the usage of in_group_p was incorrect also because it compared
to cred->fsgid and not cred->gid.

GitHub issue:
https://github.com/linux-audit/audit-kernel/issues/82

Fixes: 37eebe39c973 ("audit: improve GID/EGID comparation logic")
Cc: sta...@vger.kernel.org
Signed-off-by: Ondrej Mosnacek <omosn...@redhat.com>
---
 kernel/auditsc.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index cbab0da86d15..ec38e4d97c23 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -490,20 +490,20 @@ static int audit_filter_rules(struct task_struct *tsk,
                        result = audit_gid_comparator(cred->gid, f->op, f->gid);
                        if (f->op == Audit_equal) {
                                if (!result)
-                                       result = in_group_p(f->gid);
+                                       result = 
groups_search(cred->group_info, f->gid);
                        } else if (f->op == Audit_not_equal) {
                                if (result)
-                                       result = !in_group_p(f->gid);
+                                       result = 
!groups_search(cred->group_info, f->gid);
                        }
                        break;
                case AUDIT_EGID:
                        result = audit_gid_comparator(cred->egid, f->op, 
f->gid);
                        if (f->op == Audit_equal) {
                                if (!result)
-                                       result = in_egroup_p(f->gid);
+                                       result = 
groups_search(cred->group_info, f->gid);
                        } else if (f->op == Audit_not_equal) {
                                if (result)
-                                       result = !in_egroup_p(f->gid);
+                                       result = 
!groups_search(cred->group_info, f->gid);
                        }
                        break;
                case AUDIT_SGID:
-- 
2.17.0

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