vfscanf-internal: Remove potentially unbounded allocas

Some locales define a list of mapping pairs of alternate digits and
separators for input digits (to_inpunct).  This require the scanf
to create a list of all possible inputs for the optional type
modifier 'I'.

Checked on x86_64-linux-gnu.

Reviewed-by: Joe Simmons-Talbott <josimmon@redhat.com>

3 files changed, 115 insertions, 17 deletions

diff --git a/stdio-common/Makefile b/stdio-common/Makefile
index fe304b8373..3866362bae 100644
--- a/stdio-common/Makefile
+++ b/stdio-common/Makefile
@@ -244,6 +244,7 @@ tests := \
   tst-scanf-binary-gnu11 \
   tst-scanf-binary-gnu89 \
   tst-scanf-round \
+  tst-scanf-to_inpunct \
   tst-setvbuf1 \
   tst-sprintf \
   tst-sprintf-errno \
@@ -360,6 +361,7 @@ LOCALES := \
   de_DE.ISO-8859-1 \
   de_DE.UTF-8 \
   en_US.ISO-8859-1 \
+  fa_IR.UTF-8 \
   hi_IN.UTF-8 \
   ja_JP.EUC-JP \
   ps_AF.UTF-8 \
@@ -379,6 +381,7 @@ $(objpfx)tst-swprintf.out: $(gen-locales)
 $(objpfx)tst-vfprintf-mbs-prec.out: $(gen-locales)
 $(objpfx)tst-vfprintf-width-i18n.out: $(gen-locales)
 $(objpfx)tst-grouping3.out: $(gen-locales)
+$(objpfx)tst-scanf-to_inpunct.out: $(gen-locales)
 endif
 
 tst-printf-bz18872-ENV = MALLOC_TRACE=$(objpfx)tst-printf-bz18872.mtrace \
diff --git a/stdio-common/tst-scanf-to_inpunct.c b/stdio-common/tst-scanf-to_inpunct.c
new file mode 100644
index 0000000000..32236ac2dc
--- /dev/null
+++ b/stdio-common/tst-scanf-to_inpunct.c
@@ -0,0 +1,78 @@
+/* Test scanf for languages with mapping pairs of alternate digits and
+   separators.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
+#include <stdio.h>
+#include <support/support.h>
+#include <support/check.h>
+
+/* fa_IR defines to_inpunct for numbers.  */
+static const struct
+{
+  int n;
+  const char *str;
+} inputs[] =
+{
+  { 1,    "\xdb\xb1" },
+  { 2,    "\xdb\xb2" },
+  { 3,    "\xdb\xb3" },
+  { 4,    "\xdb\xb4" },
+  { 5,    "\xdb\xb5" },
+  { 6,    "\xdb\xb6" },
+  { 7,    "\xdb\xb7" },
+  { 8,    "\xdb\xb8" },
+  { 9,    "\xdb\xb9" },
+  { 10,   "\xdb\xb1\xdb\xb0" },
+  { 11,   "\xdb\xb1\xdb\xb1" },
+  { 12,   "\xdb\xb1\xdb\xb2" },
+  { 13,   "\xdb\xb1\xdb\xb3" },
+  { 14,   "\xdb\xb1\xdb\xb4" },
+  { 15,   "\xdb\xb1\xdb\xb5" },
+  { 16,   "\xdb\xb1\xdb\xb6" },
+  { 17,   "\xdb\xb1\xdb\xb7" },
+  { 18,   "\xdb\xb1\xdb\xb8" },
+  { 19,   "\xdb\xb1\xdb\xb9" },
+  { 20,   "\xdb\xb2\xdb\xb0" },
+  { 30,   "\xdb\xb3\xdb\xb0" },
+  { 40,   "\xdb\xb4\xdb\xb0" },
+  { 50,   "\xdb\xb5\xdb\xb0" },
+  { 60,   "\xdb\xb6\xdb\xb0" },
+  { 70,   "\xdb\xb7\xdb\xb0" },
+  { 80,   "\xdb\xb8\xdb\xb0" },
+  { 90,   "\xdb\xb9\xdb\xb0" },
+  { 100,  "\xdb\xb1\xdb\xb0\xdb\xb0" },
+  { 1000, "\xdb\xb1\xdb\xb0\xdb\xb0\xdb\xb0" },
+};
+
+static int
+do_test (void)
+{
+  xsetlocale (LC_ALL, "fa_IR.UTF-8");
+
+  for (int i = 0; i < array_length (inputs); i++)
+    {
+      int n;
+      sscanf (inputs[i].str, "%Id", &n);
+      TEST_COMPARE (n, inputs[i].n);
+    }
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/stdio-common/vfscanf-internal.c b/stdio-common/vfscanf-internal.c
index bfb9baa21a..9b1197d751 100644
--- a/stdio-common/vfscanf-internal.c
+++ b/stdio-common/vfscanf-internal.c
@@ -1455,13 +1455,14 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 	      int from_level;
 	      int to_level;
 	      int level;
+	      enum { num_digits_len = 10 };
 #ifdef COMPILE_WSCANF
-	      const wchar_t *wcdigits[10];
-	      const wchar_t *wcdigits_extended[10];
+	      const wchar_t *wcdigits[num_digits_len];
 #else
-	      const char *mbdigits[10];
-	      const char *mbdigits_extended[10];
+	      const char *mbdigits[num_digits_len];
 #endif
+	      CHAR_T *digits_extended[num_digits_len] = { NULL };
+
 	      /*  "to_inpunct" is a map from ASCII digits to their
 		  equivalent in locale. This is defined for locales
 		  which use an extra digits set.  */
@@ -1482,18 +1483,23 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 		  /*  Adding new level for extra digits set in locale file.  */
 		  ++to_level;
 
-		  for (n = 0; n < 10; ++n)
+		  for (n = 0; n < num_digits_len; ++n)
 		    {
 #ifdef COMPILE_WSCANF
 		      wcdigits[n] = (const wchar_t *)
 			_NL_CURRENT (LC_CTYPE, _NL_CTYPE_INDIGITS0_WC + n);
 
 		      wchar_t *wc_extended = (wchar_t *)
-			alloca ((to_level + 2) * sizeof (wchar_t));
+			malloc ((to_level + 2) * sizeof (wchar_t));
+		      if (wc_extended == NULL)
+			{
+			  done = EOF;
+			  goto digits_extended_fail;
+			}
 		      __wmemcpy (wc_extended, wcdigits[n], to_level);
 		      wc_extended[to_level] = __towctrans (L'0' + n, map);
 		      wc_extended[to_level + 1] = '\0';
-		      wcdigits_extended[n] = wc_extended;
+		      digits_extended[n] = wc_extended;
 #else
 		      mbdigits[n]
 			= curctype->values[_NL_CTYPE_INDIGITS0_MB + n].string;
@@ -1524,14 +1530,18 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 		      size_t mbdigits_len = last_char - mbdigits[n];
 
 		      /*  Allocate memory for extended multibyte digit.  */
-		      char *mb_extended;
-		      mb_extended = (char *) alloca (mbdigits_len + mblen + 1);
+		      char *mb_extended = malloc (mbdigits_len + mblen + 1);
+		      if (mb_extended == NULL)
+			{
+			  done = EOF;
+			  goto digits_extended_fail;
+			}
 
 		      /*  And get the mbdigits + extra_digit string.  */
 		      *(char *) __mempcpy (__mempcpy (mb_extended, mbdigits[n],
 						      mbdigits_len),
 					   extra_mbdigit, mblen) = '\0';
-		      mbdigits_extended[n] = mb_extended;
+		      digits_extended[n] = mb_extended;
 #endif
 		    }
 		}
@@ -1541,7 +1551,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 		{
 		  /* In this round we get the pointer to the digit strings
 		     and also perform the first round of comparisons.  */
-		  for (n = 0; n < 10; ++n)
+		  for (n = 0; n < num_digits_len; ++n)
 		    {
 		      /* Get the string for the digits with value N.  */
 #ifdef COMPILE_WSCANF
@@ -1553,7 +1563,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 		      DIAG_IGNORE_NEEDS_COMMENT (4.7, "-Wmaybe-uninitialized");
 
 		      if (__glibc_unlikely (map != NULL))
-			wcdigits[n] = wcdigits_extended[n];
+			wcdigits[n] = digits_extended[n];
 		      else
 			wcdigits[n] = (const wchar_t *)
 			  _NL_CURRENT (LC_CTYPE, _NL_CTYPE_INDIGITS0_WC + n);
@@ -1574,7 +1584,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 		      int avail = width > 0 ? width : INT_MAX;
 
 		      if (__glibc_unlikely (map != NULL))
-			mbdigits[n] = mbdigits_extended[n];
+			mbdigits[n] = digits_extended[n];
 		      else
 			mbdigits[n]
 			  = curctype->values[_NL_CTYPE_INDIGITS0_MB + n].string;
@@ -1617,13 +1627,13 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 #endif
 		    }
 
-		  if (n == 10)
+		  if (n == num_digits_len)
 		    {
 		      /* Have not yet found the digit.  */
 		      for (level = from_level + 1; level <= to_level; ++level)
 			{
 			  /* Search all ten digits of this level.  */
-			  for (n = 0; n < 10; ++n)
+			  for (n = 0; n < num_digits_len; ++n)
 			    {
 #ifdef COMPILE_WSCANF
 			      if (c == (wint_t) *wcdigits[n])
@@ -1679,7 +1689,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 			}
 		    }
 
-		  if (n < 10)
+		  if (n < num_digits_len)
 		    c = L_('0') + n;
 		  else if (flags & GROUP)
 		    {
@@ -1708,7 +1718,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 			{
 			  __set_errno (ENOMEM);
 			  done = EOF;
-			  goto errout;
+			  break;
 			}
 
 		      if (*cmpp != '\0')
@@ -1742,6 +1752,13 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 
 		  c = inchar ();
 		}
+
+digits_extended_fail:
+	      for (n = 0; n < num_digits_len; n++)
+		free (digits_extended[n]);
+
+	      if (done == EOF)
+		goto errout;
 	    }
 	  else
 	    /* Read the number into workspace.  */