diff mbox series

[v4] io: Fix ftw internal realloc buffer (BZ #28126)

Message ID 20210831144428.2405872-1-adhemerval.zanella@linaro.org
State Superseded
Headers show
Series [v4] io: Fix ftw internal realloc buffer (BZ #28126) | expand

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent
dj/TryBot-32bit fail Patch caused testsuite regressions

Commit Message

Adhemerval Zanella Aug. 31, 2021, 2:44 p.m. UTC
Main change is to keep track of the number of subfolders created to
avoid removing more if xmkdir bails early.

D.J has pointed out that it fails on builbot and it seems that it due
some maximum path limitation of the fuse-overlayfs filesystem which
limits the maximum folder name of 252 and a total path less than 4096,
which make the test no possible (since its idea is exactly to check
for paths *longer* than PATH_MAX).  I am not sure how to accomodate
it for fuse-overlayfs, maybe making unsupported if mkdir fails.

---

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.
---
 io/Makefile          |  1 +
 io/ftw.c             | 13 ++++---
 io/tst-ftw-bz28126.c | 81 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 90 insertions(+), 5 deletions(-)
 create mode 100644 io/tst-ftw-bz28126.c
diff mbox series

Patch

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 ce1c6a14a3..bb3ac0a7e0 100644
--- a/io/ftw.c
+++ b/io/ftw.c
@@ -392,13 +392,16 @@  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..42b7123545
--- /dev/null
+++ b/io/tst-ftw-bz28126.c
@@ -0,0 +1,81 @@ 
+/* 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 <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
+
+/* Check whether stack overflow occurs.  */
+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++)
+    {
+      xmkdir (folder, 0777);
+      xchdir (folder);
+      nsubfolders++;
+    }
+
+  TEST_COMPARE (ftw (tempdir, my_func, 20), 0);
+
+  free (tempdir);
+
+  do_cleanup ();
+
+  return 0;
+}
+
+#include <support/test-driver.c>