From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Peter Jones <pjones@redhat.com>

Date: Fri, 19 Oct 2018 10:57:52 -0400

Subject: [PATCH] Fix menu entry selection based on ID and title

Currently if grub_strtoul(saved_entry_value, NULL, 0) does not return an

error, we assume the value it has produced is a correct index into our

menu entry list, and do not try to interpret the value as the "id" or

"title" .  In cases where "id" or "title" start with a numeral, this

makes them impossible to use as selection criteria.

This patch splits the search into three phases - matching id, matching

title, and only once those have been exhausted, trying to interpret the

ID as a numeral.  In that case, we also require that the entire string

is numeric, not merely a string with leading numeric characters.

Resolves: rhbz#1640979

---

 grub-core/normal/menu.c | 146 +++++++++++++++++++++++++-----------------------

 1 file changed, 75 insertions(+), 71 deletions(-)

diff --git a/grub-core/normal/menu.c b/grub-core/normal/menu.c

index 6cb2a071490..95f7abaf2fd 100644

--- a/grub-core/normal/menu.c

+++ b/grub-core/normal/menu.c

@@ -164,12 +164,12 @@ grub_menu_set_timeout (int timeout)

 }

 static int

-menuentry_eq (const char *id, const char *spec)

+menuentry_eq (const char *id, const char *spec, int limit)

 {

   const char *ptr1, *ptr2;

   ptr1 = id;

   ptr2 = spec;

-  while (1)

+  while (limit == -1 || ptr1 - id <= limit)

     {

       if (*ptr2 == '>' && ptr2[1] != '>' && *ptr1 == 0)

 	return ptr2 - spec;

@@ -178,7 +178,11 @@ menuentry_eq (const char *id, const char *spec)

       if (*ptr2 == '>')

 	ptr2++;

       if (*ptr1 != *ptr2)

-	return 0;

+	{

+	  if (limit > -1 && ptr1 - id == limit && !*ptr1 && grub_isspace(*ptr2))

+	    return ptr1 -id -1;

+	  return 0;

+	}

       if (*ptr1 == 0)

 	return ptr1 - id;

       ptr1++;

@@ -187,6 +191,61 @@ menuentry_eq (const char *id, const char *spec)

   return 0;

 }

+static int

+get_entry_number_helper(grub_menu_t menu,

+			const char * const val, const char ** const tail)

+{

+  /* See if the variable matches the title of a menu entry.  */

+  int entry = -1;

+  grub_menu_entry_t e;

+  int i;

+

+  for (i = 0, e = menu->entry_list; e; i++)

+    {

+      int l = 0;

+      while (val[l] && !grub_isspace(val[l]))

+	l++;

+

+      if (menuentry_eq (e->id, val, l))

+	{

+	  if (tail)

+	    *tail = val + l;

+	  return i;

+	}

+      e = e->next;

+    }

+

+  for (i = 0, e = menu->entry_list; e; i++)

+    {

+      int l = 0;

+      while (val[l] && !grub_isspace(val[l]))

+	l++;

+

+      if (menuentry_eq (e->title, val, l))

+	{

+	  if (tail)

+	    *tail = val + l;

+	  return i;

+	}

+      e = e->next;

+    }

+

+  if (tail)

+    *tail = NULL;

+

+  entry = (int) grub_strtoul (val, tail, 0);

+  if (grub_errno == GRUB_ERR_BAD_NUMBER ||

+      (*tail && **tail && !grub_isspace(**tail)))

+    {

+      entry = -1;

+      if (tail)

+	*tail = NULL;

+      grub_errno = GRUB_ERR_NONE;

+    }

+

+  return entry;

+}

+

 /* Get the first entry number from the value of the environment variable NAME,

    which is a space-separated list of non-negative integers.  The entry number

    which is returned is stripped from the value of NAME.  If no entry number

@@ -195,9 +254,8 @@ static int

 get_and_remove_first_entry_number (grub_menu_t menu, const char *name)

 {

   const char *val;

-  char *tail;

+  const char *tail;

   int entry;

-  int sz = 0;

   val = grub_env_get (name);

   if (! val)

@@ -205,50 +263,24 @@ get_and_remove_first_entry_number (grub_menu_t menu, const char *name)

   grub_error_push ();

-  entry = (int) grub_strtoul (val, &tail, 0);

+  entry = get_entry_number_helper(menu, val, &tail);

+  if (!(*tail == 0 || grub_isspace(*tail)))

+    entry = -1;

-  if (grub_errno == GRUB_ERR_BAD_NUMBER)

+  if (entry >= 0)

     {

-      /* See if the variable matches the title of a menu entry.  */

-      grub_menu_entry_t e = menu->entry_list;

-      int i;

-

-      for (i = 0; e; i++)

-	{

-	  sz = menuentry_eq (e->title, val);

-	  if (sz < 1)

-	    sz = menuentry_eq (e->id, val);

-

-	  if (sz >= 1)

-	    {

-	      entry = i;

-	      break;

-	    }

-	  e = e->next;

-	}

-

-      if (sz > 0)

-	grub_errno = GRUB_ERR_NONE;

-

-      if (! e)

-	entry = -1;

-    }

-

-  if (grub_errno == GRUB_ERR_NONE)

-    {

-      if (sz > 0)

-	tail += sz;

-

       /* Skip whitespace to find the next entry.  */

       while (*tail && grub_isspace (*tail))

 	tail++;

-      grub_env_set (name, tail);

+      if (*tail)

+	grub_env_set (name, tail);

+      else

+	grub_env_unset (name);

     }

   else

     {

       grub_env_unset (name);

       grub_errno = GRUB_ERR_NONE;

-      entry = -1;

     }

   grub_error_pop ();

@@ -525,6 +557,7 @@ static int

 get_entry_number (grub_menu_t menu, const char *name)

 {

   const char *val;

+  const char *tail;

   int entry;

   val = grub_env_get (name);

@@ -532,38 +565,9 @@ get_entry_number (grub_menu_t menu, const char *name)

     return -1;

   grub_error_push ();

-

-  entry = (int) grub_strtoul (val, 0, 0);

-

-  if (grub_errno == GRUB_ERR_BAD_NUMBER)

-    {

-      /* See if the variable matches the title of a menu entry.  */

-      grub_menu_entry_t e = menu->entry_list;

-      int i;

-

-      grub_errno = GRUB_ERR_NONE;

-

-      for (i = 0; e; i++)

-	{

-	  if (menuentry_eq (e->title, val)

-	      || menuentry_eq (e->id, val))

-	    {

-	      entry = i;

-	      break;

-	    }

-	  e = e->next;

-	}

-

-      if (! e)

-	entry = -1;

-    }

-

-  if (grub_errno != GRUB_ERR_NONE)

-    {

-      grub_errno = GRUB_ERR_NONE;

-      entry = -1;

-    }

-

+  entry = get_entry_number_helper(menu, val, &tail);

+  if (*tail != '\0')

+    entry = -1;

   grub_error_pop ();

   return entry;