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stdio-common: Add tst-memstream-string for open_memstream overflow 

This code path is exercised indirectly by some of the DNS stub
resolver tests, via their own use of xopen_memstream for constructing
strings describing result data.  The relative lack of test suite
coverage became apparent when these tests starting failing after a
printf changes uncovered bug 28949.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer 2022-05-23 10:08:18 +02:00
parent b094c52b1b
commit 0060a6de54
2 changed files with 80 additions and 0 deletions
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3
stdio-common/Makefile
View File

@ -175,6 +175,7 @@ tests := \
tst-gets \
tst-grouping \
tst-long-dbl-fphex \
tst-memstream-string \
tst-obprintf \
tst-perror \
tst-popen \
@ -390,6 +391,8 @@ CFLAGS-tst-gets.c += -Wno-deprecated-declarations
# the fortified version had the same bug.
CFLAGS-tst-bz11319-fortify2.c += -D_FORTIFY_SOURCE=2
CFLAGS-tst-memstream-string.c += -fno-builtin-fprintf
CPPFLAGS += $(libio-mtsafe)
$(objpfx)tst-setvbuf1.out: /dev/null $(objpfx)tst-setvbuf1

77
stdio-common/tst-memstream-string.c Normal file
View File

@ -0,0 +1,77 @@
/* Test writing differently sized strings to a memstream.
Copyright (C) 2022 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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <support/check.h>
#include <support/support.h>
#include <support/xmemstream.h>
/* Returns a printable ASCII character based on INDEX. */
static inline char
char_from_index (unsigned int index)
{
return ' ' + (index % 95);
}
enum { result_size = 25000 };
static void
run_one_size (unsigned int chunk_size)
{
char *chunk = xmalloc (chunk_size + 1);
struct xmemstream mem;
xopen_memstream (&mem);
unsigned int written = 0;
for (unsigned int i = 0; i < result_size; )
{
unsigned int to_print = result_size - i;
if (to_print > chunk_size)
to_print = chunk_size;
for (unsigned int j = 0; j < to_print; ++j)
chunk[j] = char_from_index(i + j);
chunk[to_print] = '\0';
fprintf (mem.out, "%s", chunk); /* Needs -fno-builtin-fprintf. */
i += to_print;
written += strlen(chunk);
}
xfclose_memstream (&mem);
TEST_COMPARE (written, result_size);
TEST_COMPARE (mem.length, result_size);
TEST_COMPARE (strlen (mem.buffer), result_size);
for (unsigned int i = 0; i < result_size; ++i)
TEST_COMPARE (mem.buffer[i], char_from_index (i));
free (mem.buffer);
free (chunk);
}
static int
do_test (void)
{
for (unsigned int chunk_size = 1; chunk_size <= 30; ++ chunk_size)
run_one_size (chunk_size);
return 0;
}
#include <support/test-driver.c>