From: Glenn Washburn <development@efficientek.com>
Date: Tue, 15 Feb 2022 18:36:43 +0000 (-0600)
Subject: mm: Temporarily disable grub_mm_debug while calling grub_vprintf() in grub_printf()
X-Git-Tag: grub-2.12-rc1~476
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a4430355a3237fc756480349e9167667b0e89476;p=thirdparty%2Fgrub.git

mm: Temporarily disable grub_mm_debug while calling grub_vprintf() in grub_printf()

To prevent infinite recursion when grub_mm_debug is on, disable it when
calling grub_vprintf(). One such call loop is:
  grub_vprintf() -> parse_printf_args() -> parse_printf_arg_fmt() ->
    grub_debug_calloc() -> grub_printf() -> grub_vprintf().

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---

diff --git a/grub-core/kern/misc.c b/grub-core/kern/misc.c
index de40f566d..18bde5d50 100644
--- a/grub-core/kern/misc.c
+++ b/grub-core/kern/misc.c
@@ -113,10 +113,30 @@ grub_printf (const char *fmt, ...)
   va_list ap;
   int ret;
 
+#if defined(MM_DEBUG) && !defined(GRUB_UTIL) && !defined (GRUB_MACHINE_EMU)
+  /*
+   * To prevent infinite recursion when grub_mm_debug is on, disable it
+   * when calling grub_vprintf(). One such call loop is:
+   *   grub_vprintf() -> parse_printf_args() -> parse_printf_arg_fmt() ->
+   *     grub_debug_calloc() -> grub_printf() -> grub_vprintf().
+   */
+  int grub_mm_debug_save = 0;
+
+  if (grub_mm_debug)
+    {
+      grub_mm_debug_save = grub_mm_debug;
+      grub_mm_debug = 0;
+    }
+#endif
+
   va_start (ap, fmt);
   ret = grub_vprintf (fmt, ap);
   va_end (ap);
 
+#if defined(MM_DEBUG) && !defined(GRUB_UTIL) && !defined (GRUB_MACHINE_EMU)
+  grub_mm_debug = grub_mm_debug_save;
+#endif
+
   return ret;
 }