db: Avoid undefined behavior when copying cm2/cm3 from the db

memcpy has both the source and destination marked as non-null and
we were still passing NULL (with a zero size) to it. While this
makes sense it violates the constraints of the function. Add the
check to see if these values are NULL or not.

+db.c:583:2: runtime error: null pointer passed as argument 2, which is declared to never be null
+    #0 0x40d7f7 in get_equipment_by_subscr (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x40d7f7)
+    #1 0x40f6d2 in db_get_subscriber (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x40f6d2)
+    #2 0x40bfaa in sms_from_result_v3 (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x40bfaa)
+    #3 0x40c847 in update_db_revision_3 (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x40c847)
+    #4 0x40cbc3 in check_db_revision (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x40cbc3)
+    #5 0x40cf85 in db_prepare (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x40cf85)
+    #6 0x406f18 in main /home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test.c:179
+    #7 0x7fd625638a3f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x20a3f)
+    #8 0x405598 in _start (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x405598)
+
+db.c:590:2: runtime error: null pointer passed as argument 2, which is declared to never be null
+    #0 0x40da23 in get_equipment_by_subscr (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x40da23)
+    #1 0x40f6d2 in db_get_subscriber (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x40f6d2)
+    #2 0x40bfaa in sms_from_result_v3 (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x40bfaa)
+    #3 0x40c847 in update_db_revision_3 (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x40c847)
+    #4 0x40cbc3 in check_db_revision (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x40cbc3)
+    #5 0x40cf85 in db_prepare (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x40cf85)
+    #6 0x406f18 in main /home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test.c:179
+    #7 0x7fd625638a3f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x20a3f)
+    #8 0x405598 in _start (/home/builder/jenkins/workspace/Osmocom_Sanitizer/source/openbsc/openbsc/tests/db/db_test+0x405598)
1 file changed
tree: 8dc98279965f2b4673e553618d7367f9e18bbf8e
  1. debian/
  2. openbsc/
  3. .gitignore