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* [glibc] stdio-common: Add tst-memstream-string for open_memstream overflow
@ 2022-05-23 9:08 Florian Weimer
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From: Florian Weimer @ 2022-05-23 9:08 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=0060a6de5493aeb4af457511e9b9ab532a6930a5
commit 0060a6de5493aeb4af457511e9b9ab532a6930a5
Author: Florian Weimer <fweimer@redhat.com>
Date: Mon May 23 10:08:18 2022 +0200
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>
Diff:
---
stdio-common/Makefile | 3 ++
stdio-common/tst-memstream-string.c | 77 +++++++++++++++++++++++++++++++++++++
2 files changed, 80 insertions(+)
diff --git a/stdio-common/Makefile b/stdio-common/Makefile
index 2750334714..b1e9144de0 100644
--- a/stdio-common/Makefile
+++ b/stdio-common/Makefile
@@ -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
diff --git a/stdio-common/tst-memstream-string.c b/stdio-common/tst-memstream-string.c
new file mode 100644
index 0000000000..0a31e0c12c
--- /dev/null
+++ b/stdio-common/tst-memstream-string.c
@@ -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>
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