tpm2-util: dont't find best PCR bank if no PCRs are selected whatsoever

This will otherwise just yield weird log message, complaining that PCRs
were not initialized. But which PCRs if we have none selected?

diff --git a/src/shared/tpm2-util.c b/src/shared/tpm2-util.c
index 8d5097135616cc730b5edcf77c45e907253543a5..4bb17157e276777eb2d7707c053995406a505992 100644 (file)
--- a/src/shared/tpm2-util.c
+++ b/src/shared/tpm2-util.c
@@ -2539,6 +2539,12 @@ int tpm2_get_best_pcr_bank(
         assert(c);
         assert(ret);
 
+        if (pcr_mask == 0) {
+                log_debug("Asked to pick best PCR bank but no PCRs selected we could derive this from. Defaulting to SHA256.");
+                *ret = TPM2_ALG_SHA256; /* if no PCRs are selected this doesn't matter anyway... */
+                return 0;
+        }
+
         FOREACH_TPMS_PCR_SELECTION_IN_TPML_PCR_SELECTION(selection, &c->capability_pcrs) {
                 TPMI_ALG_HASH hash = selection->hash;
                 int good;