acpi-fpdt: break on zero or negative length read

https://bugzilla.redhat.com/show_bug.cgi?id=1027478

diff --git a/src/shared/acpi-fpdt.c b/src/shared/acpi-fpdt.c
index 75648b4d86f91af3a4327c11232d2630c91da6c3..7bae47f85f2fb5199e301233f092a984a002798c 100644 (file)
--- a/src/shared/acpi-fpdt.c
+++ b/src/shared/acpi-fpdt.c
@@ -109,6 +109,8 @@ int acpi_get_boot_usec(usec_t *loader_start, usec_t *loader_exit) {
         for (rec = (struct acpi_fpdt_header *)(buf + sizeof(struct acpi_table_header));
              (char *)rec < buf + l;
              rec = (struct acpi_fpdt_header *)((char *)rec + rec->length)) {
+                if (rec->length <= 0)
+                        break;
                 if (rec->type != ACPI_FPDT_TYPE_BOOT)
                         continue;
                 if (rec->length != sizeof(struct acpi_fpdt_header))