On Mon, Aug 19, 2019 at 04:41:11PM -0700, Kees Cook wrote:
diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 588dd59a5b72..da471fcc5487 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -10,6 +10,7 @@
#define BUGFLAG_WARNING (1 << 0)
#define BUGFLAG_ONCE (1 << 1)
#define BUGFLAG_DONE (1 << 2)
+#define BUGFLAG_PRINTK (1 << 3)
#define BUGFLAG_TAINT(taint) ((taint) << 8)
#define BUG_GET_TAINT(bug) ((bug)->flags >> 8)
#endif
diff --git a/lib/bug.c b/lib/bug.c
index 1077366f496b..6c22e8a6f9de 100644
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -181,6 +181,15 @@ enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
}
}
+ /*
+ * BUG() and WARN_ON() families don't print a custom debug message
+ * before triggering the exception handler, so we must add the
+ * "cut here" line now. WARN() issues its own "cut here" before the
+ * extra debugging message it writes before triggering the handler.
+ */
+ if ((bug->flags & BUGFLAG_PRINTK) == 0)
+ printk(KERN_DEFAULT CUT_HERE);
I'm not loving that BUGFLAG_PRINTK name, BUGFLAG_CUT_HERE makes more
sense to me.