Fix buffer overrun in EUC-KR conversion module (bz #24973)

The byte 0xfe as input to the EUC-KR conversion denotes a user-defined
area and is not allowed.  The from_euc_kr function used to skip two bytes
when told to skip over the unknown designation, potentially running over
the buffer end.

1 files changed, 53 insertions, 0 deletions

diff --git a/iconvdata/bug-iconv13.c b/iconvdata/bug-iconv13.c
new file mode 100644
index 0000000..87aaff3
--- /dev/null
+++ b/iconvdata/bug-iconv13.c
@@ -0,0 +1,53 @@
+/* bug 24973: Test EUC-KR module
+   Copyright (C) 2020 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 <errno.h>
+#include <iconv.h>
+#include <stdio.h>
+#include <support/check.h>
+
+static int
+do_test (void)
+{
+  iconv_t cd = iconv_open ("UTF-8//IGNORE", "EUC-KR");
+  TEST_VERIFY_EXIT (cd != (iconv_t) -1);
+
+  /* 0xfe (->0x7e : row 94) and 0xc9 (->0x49 : row 41) are user-defined
+     areas, which are not allowed and should be skipped over due to
+     //IGNORE.  The trailing 0xfe also is an incomplete sequence, which
+     should be checked first.  */
+  char input[4] = { '\xc9', '\xa1', '\0', '\xfe' };
+  char *inptr = input;
+  size_t insize = sizeof (input);
+  char output[4];
+  char *outptr = output;
+  size_t outsize = sizeof (output);
+
+  /* This used to crash due to buffer overrun.  */
+  TEST_VERIFY (iconv (cd, &inptr, &insize, &outptr, &outsize) == (size_t) -1);
+  TEST_VERIFY (errno == EINVAL);
+  /* The conversion should produce one character, the converted null
+     character.  */
+  TEST_VERIFY (sizeof (output) - outsize == 1);
+
+  TEST_VERIFY_EXIT (iconv_close (cd) != -1);
+
+  return 0;
+}
+
+#include <support/test-driver.c>