gettext: Integer overflow leads to heap OOB write

The size calculation of the translation buffer in
grub_gettext_getstr_from_position() may overflow
to 0 leading to heap OOB write. This patch fixes
the issue by using grub_add() and checking for
an overflow.

Fixes: CVE-2024-45777
Reported-by: Nils Langius <nils@langius.de>
Signed-off-by: Lidong Chen <lidong.chen@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Alec Brown <alec.r.brown@oracle.com>

diff --git a/grub-core/gettext/gettext.c b/grub-core/gettext/gettext.c
index 63bb1ab73f2cfce7569a24ab932e782dda509b0f..9ffc734284e9985118d5331e6826e580300454b2 100644 (file)
--- a/grub-core/gettext/gettext.c
+++ b/grub-core/gettext/gettext.c
@@ -26,6 +26,7 @@
 #include <grub/file.h>
 #include <grub/kernel.h>
 #include <grub/i18n.h>
+#include <grub/safemath.h>
 
 GRUB_MOD_LICENSE ("GPLv3+");
 
@@ -99,6 +100,7 @@ grub_gettext_getstr_from_position (struct grub_gettext_context *ctx,
   char *translation;
   struct string_descriptor desc;
   grub_err_t err;
+  grub_size_t alloc_sz;
 
   internal_position = (off + position * sizeof (desc));
 
@@ -109,7 +111,10 @@ grub_gettext_getstr_from_position (struct grub_gettext_context *ctx,
   length = grub_cpu_to_le32 (desc.length);
   offset = grub_cpu_to_le32 (desc.offset);
 
-  translation = grub_malloc (length + 1);
+  if (grub_add (length, 1, &alloc_sz))
+    return NULL;
+
+  translation = grub_malloc (alloc_sz);
   if (!translation)
     return NULL;