* [PATCH v5] io: Fix ftw internal realloc buffer (BZ #28126)
@ 2021-09-07 12:33 Adhemerval Zanella
2021-09-13 13:15 ` Siddhesh Poyarekar
0 siblings, 1 reply; 2+ messages in thread
From: Adhemerval Zanella @ 2021-09-07 12:33 UTC (permalink / raw)
To: libc-alpha
The 106ff08526d3ca did not take in consideration the buffer might be
reallocated if the total path is larger than PATH_MAX. The realloc
uses 'dirbuf', where 'dirstreams' is the allocated buffer.
Checked on x86_64-linux-gnu.
---
Changes in v5:
- Fail as unsupported if the large path can not be created, so it
do not regress on filesystem that do no support it (such as
overlayfs used on buildbot).
---
io/Makefile | 1 +
io/ftw.c | 13 ++++---
io/tst-ftw-bz28126.c | 92 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 101 insertions(+), 5 deletions(-)
create mode 100644 io/tst-ftw-bz28126.c
diff --git a/io/Makefile b/io/Makefile
index 9871ecbc74..ecf65aba60 100644
--- a/io/Makefile
+++ b/io/Makefile
@@ -79,6 +79,7 @@ tests := test-utime test-stat test-stat2 test-lfs tst-getcwd \
tst-futimens \
tst-utimensat \
tst-closefrom \
+ tst-ftw-bz28126
tests-time64 := \
tst-futimens-time64 \
diff --git a/io/ftw.c b/io/ftw.c
index f0db173727..3964c07bbb 100644
--- a/io/ftw.c
+++ b/io/ftw.c
@@ -391,13 +391,16 @@ process_entry (struct ftw_data *data, struct dir_data *dir, const char *name,
if (data->dirbufsize < new_buflen)
{
/* Enlarge the buffer. */
- char *newp;
-
- data->dirbufsize = 2 * new_buflen;
- newp = (char *) realloc (data->dirbuf, data->dirbufsize);
+ size_t newsize = 2 * new_buflen;
+ void *newp = realloc (data->dirstreams, data->maxdir
+ * sizeof (struct dir_data *)
+ + newsize);
if (newp == NULL)
return -1;
- data->dirbuf = newp;
+ data->dirstreams = newp;
+ data->dirbufsize = newsize;
+ data->dirbuf = (char *) data->dirstreams
+ + data->maxdir * sizeof (struct dir_data *);
}
*((char *) __mempcpy (data->dirbuf + data->ftw.base, name, namlen)) = '\0';
diff --git a/io/tst-ftw-bz28126.c b/io/tst-ftw-bz28126.c
new file mode 100644
index 0000000000..565cd92cfd
--- /dev/null
+++ b/io/tst-ftw-bz28126.c
@@ -0,0 +1,92 @@
+/* Check if internal buffer reallocation work for large paths (BZ #28126)
+ Copyright (C) 2021 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 <ftw.h>
+#include <limits.h>
+#include <string.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/temp_file.h>
+#include <support/xunistd.h>
+#include <stdio.h>
+
+static int
+my_func (const char *file, const struct stat *sb, int flag)
+{
+ return 0;
+}
+
+static const char folder[NAME_MAX] = { [0 ... 253] = 'a', [254] = '\0' };
+
+#define NSUBFOLDERS 16
+static int nsubfolders;
+
+static void
+do_cleanup (void)
+{
+ xchdir ("..");
+ for (int i = 0; i < nsubfolders; i++)
+ {
+ remove (folder);
+ xchdir ("..");
+ }
+ remove (folder);
+}
+#define CLEANUP_HANDLER do_cleanup
+
+static int
+do_test (void)
+{
+ char *tempdir = support_create_temp_directory ("tst-bz28126");
+
+ /* Create path with various subfolders to force an internal buffer
+ reallocation within ntfw. */
+ char *path = xasprintf ("%s/%s", tempdir, folder);
+ xmkdir (path, 0777);
+ xchdir (path);
+ free (path);
+ for (int i = 0; i < NSUBFOLDERS - 1; i++)
+ {
+ int r = mkdir (folder, 0777);
+ /* Some filesystem such as overlayfs does not support larger
+ path required to trigger the internal buffer reallocation. */
+ if (r != 0)
+ {
+ if (errno == ENAMETOOLONG)
+ FAIL_UNSUPPORTED ("the filesystem does not support the required"
+ "large path");
+ else
+ FAIL_EXIT1 ("mkdir (\"%s\", 0%o): %m", folder, 0777);
+ }
+
+ xchdir (folder);
+ nsubfolders++;
+ }
+
+ TEST_COMPARE (ftw (tempdir, my_func, 20), 0);
+
+ free (tempdir);
+
+ do_cleanup ();
+
+ return 0;
+}
+
+#include <support/test-driver.c>
--
2.30.2
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2021-09-07 12:33 [PATCH v5] io: Fix ftw internal realloc buffer (BZ #28126) Adhemerval Zanella
2021-09-13 13:15 ` Siddhesh Poyarekar
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