[PATCH 5/6] libsepol: refuse to load policies with no block

[Nicolas Iooss <nicolas.iooss@xxxxxxx>]

Some functions assumes that p->global is not NULL. For example
range_read() contains:

    p->global->enabled->range_tr_rules = rtr;

However p->global may currently be NULL when loading a policy module
with no avrule block. Avoid a NULL pointer dereference by making such a
policy invalid.

Signed-off-by: Nicolas Iooss <nicolas.iooss@xxxxxxx>
---
 libsepol/src/policydb.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/libsepol/src/policydb.c b/libsepol/src/policydb.c
index 3cff6d276d68..7093b29833bf 100644
--- a/libsepol/src/policydb.c
+++ b/libsepol/src/policydb.c
@@ -4044,6 +4044,10 @@ int policydb_read(policydb_t * p, struct policy_file *fp, unsigned verbose)
 		if (avrule_block_read(p, &p->global, info->sym_num, fp) == -1) {
 			goto bad;
 		}
+		if (p->global == NULL) {
+			ERR(fp->handle, "no avrule block in policy");
+			goto bad;
+		}
 		for (i = 0; i < info->sym_num; i++) {
 			if ((rc = next_entry(buf, fp, sizeof(uint32_t))) < 0) {
 				goto bad;
-- 
2.12.0

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