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cpio: fix CVE-2016-2037 ; out-of-bounds and segfaults
2019-01-03 05:16:33 +01:00
From 5abe86f88de3c61e369483a55afe771cce646135 Mon Sep 17 00:00:00 2001
From: Pavel Raiskup <praiskup@redhat.com>
Date: Tue, 26 Jan 2016 23:17:54 +0100
Subject: [PATCH 3/4] CVE-2016-2037 - 1 byte out-of-bounds write
Ensure that cpio_safer_name_suffix always works with dynamically
allocated buffer, and that it has size of at least 32 bytes.
Then, any call to cpio_safer_name_suffix is safe (it requires at
least 2 bytes in the buffer).
Also ensure that c_namesize is always correctly initialized (by
cpio_set_c_name) to avoid undefined behavior when reading
file_hdr.c_namesize (previously happened for tar archives).
References:
http://www.mail-archive.com/bug-cpio@gnu.org/msg00545.html
* src/copyin.c (query_rename): Drop the hack, as we now work with
dynamically allocated buffer. Use cpio_set_c_name.
(create_defered_links_to_skipped): Use cpio_set_c_name rather than
manual assignment.
(read_name_from_file): New function to avoid C&P.
(read_in_old_ascii, read_in_new_ascii, read_in_binary): Use
read_name_from_file.
(process_copy_in): Initialize file_hdr.c_namesize.
* src/copyout.c (process_copy_out): Use cpio_set_c_name.
* src/cpiohdr.h (cpio_set_c_name): New prototype.
* src/tar.c (read_in_tar_header): Use cpio_set_c_name.
* src/util.c (cpio_set_c_name): New function to set
file_hdr->c_name and c_namesize from arbitrary string.
(cpio_safer_name_suffix): Some docs fixes.
* tests/inout.at: Also test copy-in, and try various formats.
---
src/copyin.c | 68 ++++++++++++++++----------------------------------
src/copyout.c | 13 ++++------
src/cpiohdr.h | 1 +
src/tar.c | 10 +++++---
src/util.c | 32 +++++++++++++++++++++++-
tests/inout.at | 19 ++++++++++++--
6 files changed, 82 insertions(+), 61 deletions(-)
diff --git src/copyin.c src/copyin.c
index 05279d2..06ee1c3 100644
--- src/copyin.c
+++ src/copyin.c
@@ -76,28 +76,7 @@ query_rename(struct cpio_file_stat* file_hdr, FILE *tty_in, FILE *tty_out,
return -1;
}
else
- /* Debian hack: file_hrd.c_name is sometimes set to
- point to static memory by code in tar.c. This
- causes a segfault. This has been fixed and an
- additional check to ensure that the file name
- is not too long has been added. (Reported by
- Horst Knobloch.) This bug has been reported to
- "bug-gnu-utils@prep.ai.mit.edu". (99/1/6) -BEM */
- {
- if (archive_format != arf_tar && archive_format != arf_ustar)
- {
- free (file_hdr->c_name);
- file_hdr->c_name = xstrdup (new_name.ds_string);
- }
- else
- {
- if (is_tar_filename_too_long (new_name.ds_string))
- error (0, 0, _("%s: file name too long"),
- new_name.ds_string);
- else
- strcpy (file_hdr->c_name, new_name.ds_string);
- }
- }
+ cpio_set_c_name (file_hdr, new_name.ds_string);
return 0;
}
@@ -344,8 +323,7 @@ create_defered_links_to_skipped (struct cpio_file_stat *file_hdr,
d_prev->next = d->next;
else
deferments = d->next;
- free (file_hdr->c_name);
- file_hdr->c_name = xstrdup(d->header.c_name);
+ cpio_set_c_name (file_hdr, d->header.c_name);
free_deferment (d);
copyin_regular_file(file_hdr, in_file_des);
return 0;
@@ -1064,6 +1042,22 @@ read_in_header (struct cpio_file_stat *file_hdr, int in_des)
}
}
+static void
+read_name_from_file (struct cpio_file_stat *file_hdr, int fd, uintmax_t len)
+{
+ static char *tmp_filename;
+ static size_t buflen;
+
+ if (buflen < len)
+ {
+ buflen = len;
+ tmp_filename = xrealloc (tmp_filename, buflen);
+ }
+
+ tape_buffered_read (tmp_filename, fd, len);
+ cpio_set_c_name (file_hdr, tmp_filename);
+}
+
/* Fill in FILE_HDR by reading an old-format ASCII format cpio header from
file descriptor IN_DES, except for the magic number, which is
already filled in. */
@@ -1090,14 +1084,8 @@ read_in_old_ascii (struct cpio_file_stat *file_hdr, int in_des)
file_hdr->c_rdev_min = minor (dev);
file_hdr->c_mtime = FROM_OCTAL (ascii_header.c_mtime);
- file_hdr->c_namesize = FROM_OCTAL (ascii_header.c_namesize);
file_hdr->c_filesize = FROM_OCTAL (ascii_header.c_filesize);
-
- /* Read file name from input. */
- if (file_hdr->c_name != NULL)
- free (file_hdr->c_name);
- file_hdr->c_name = (char *) xmalloc (file_hdr->c_namesize + 1);
- tape_buffered_read (file_hdr->c_name, in_des, (long) file_hdr->c_namesize);
+ read_name_from_file (file_hdr, in_des, FROM_OCTAL (ascii_header.c_namesize));
/* HP/UX cpio creates archives that look just like ordinary archives,
but for devices it sets major = 0, minor = 1, and puts the
@@ -1152,14 +1140,8 @@ read_in_new_ascii (struct cpio_file_stat *file_hdr, int in_des)
file_hdr->c_dev_min = FROM_HEX (ascii_header.c_dev_min);
file_hdr->c_rdev_maj = FROM_HEX (ascii_header.c_rdev_maj);
file_hdr->c_rdev_min = FROM_HEX (ascii_header.c_rdev_min);
- file_hdr->c_namesize = FROM_HEX (ascii_header.c_namesize);
file_hdr->c_chksum = FROM_HEX (ascii_header.c_chksum);
-
- /* Read file name from input. */
- if (file_hdr->c_name != NULL)
- free (file_hdr->c_name);
- file_hdr->c_name = (char *) xmalloc (file_hdr->c_namesize);
- tape_buffered_read (file_hdr->c_name, in_des, (long) file_hdr->c_namesize);
+ read_name_from_file (file_hdr, in_des, FROM_HEX (ascii_header.c_namesize));
/* In SVR4 ASCII format, the amount of space allocated for the header
is rounded up to the next long-word, so we might need to drop
@@ -1207,16 +1189,9 @@ read_in_binary (struct cpio_file_stat *file_hdr,
file_hdr->c_rdev_min = minor (short_hdr->c_rdev);
file_hdr->c_mtime = (unsigned long) short_hdr->c_mtimes[0] << 16
| short_hdr->c_mtimes[1];
-
- file_hdr->c_namesize = short_hdr->c_namesize;
file_hdr->c_filesize = (unsigned long) short_hdr->c_filesizes[0] << 16
| short_hdr->c_filesizes[1];
-
- /* Read file name from input. */
- if (file_hdr->c_name != NULL)
- free (file_hdr->c_name);
- file_hdr->c_name = (char *) xmalloc (file_hdr->c_namesize);
- tape_buffered_read (file_hdr->c_name, in_des, (long) file_hdr->c_namesize);
+ read_name_from_file (file_hdr, in_des, short_hdr->c_namesize);
/* In binary mode, the amount of space allocated in the header for
the filename is `c_namesize' rounded up to the next short-word,
@@ -1297,6 +1272,7 @@ process_copy_in ()
read_pattern_file ();
}
file_hdr.c_name = NULL;
+ file_hdr.c_namesize = 0;
if (rename_batch_file)
{
diff --git src/copyout.c src/copyout.c
index 1f0987a..bb39559 100644
--- src/copyout.c
+++ src/copyout.c
@@ -660,8 +660,7 @@ process_copy_out ()
cpio_safer_name_suffix (input_name.ds_string, false,
!no_abs_paths_flag, true);
#ifndef HPUX_CDF
- file_hdr.c_name = input_name.ds_string;
- file_hdr.c_namesize = strlen (input_name.ds_string) + 1;
+ cpio_set_c_name (&file_hdr, input_name.ds_string);
#else
if ( (archive_format != arf_tar) && (archive_format != arf_ustar) )
{
@@ -670,16 +669,15 @@ process_copy_out ()
properly recreate the directory as hidden (in case the
files of a directory go into the archive before the
directory itself (e.g from "find ... -depth ... | cpio")). */
- file_hdr.c_name = add_cdf_double_slashes (input_name.ds_string);
- file_hdr.c_namesize = strlen (file_hdr.c_name) + 1;
+ cpio_set_c_name (&file_hdr,
+ add_cdf_double_slashes (input_name.ds_string));
}
else
{
/* We don't mark CDF's in tar files. We assume the "hidden"
directory will always go into the archive before any of
its files. */
- file_hdr.c_name = input_name.ds_string;
- file_hdr.c_namesize = strlen (input_name.ds_string) + 1;
+ cpio_set_c_name (&file_hdr, input_name.ds_string);
}
#endif
@@ -866,8 +864,7 @@ process_copy_out ()
file_hdr.c_chksum = 0;
file_hdr.c_filesize = 0;
- file_hdr.c_namesize = 11;
- file_hdr.c_name = CPIO_TRAILER_NAME;
+ cpio_set_c_name (&file_hdr, CPIO_TRAILER_NAME);
if (archive_format != arf_tar && archive_format != arf_ustar)
write_out_header (&file_hdr, out_file_des);
else
diff --git src/cpiohdr.h src/cpiohdr.h
index b29e6fb..f4c63be 100644
--- src/cpiohdr.h
+++ src/cpiohdr.h
@@ -129,5 +129,6 @@ struct cpio_file_stat /* Internal representation of a CPIO header */
char *c_tar_linkname;
};
+void cpio_set_c_name(struct cpio_file_stat *file_hdr, char *name);
#endif /* cpiohdr.h */
diff --git src/tar.c src/tar.c
index a2ce171..e41f89d 100644
--- src/tar.c
+++ src/tar.c
@@ -282,7 +282,7 @@ read_in_tar_header (struct cpio_file_stat *file_hdr, int in_des)
if (null_block ((long *) &tar_rec, TARRECORDSIZE))
#endif
{
- file_hdr->c_name = CPIO_TRAILER_NAME;
+ cpio_set_c_name (file_hdr, CPIO_TRAILER_NAME);
return;
}
#if 0
@@ -316,9 +316,11 @@ read_in_tar_header (struct cpio_file_stat *file_hdr, int in_des)
}
if (archive_format != arf_ustar)
- file_hdr->c_name = stash_tar_filename (NULL, tar_hdr->name);
+ cpio_set_c_name (file_hdr, stash_tar_filename (NULL, tar_hdr->name));
else
- file_hdr->c_name = stash_tar_filename (tar_hdr->prefix, tar_hdr->name);
+ cpio_set_c_name (file_hdr, stash_tar_filename (tar_hdr->prefix,
+ tar_hdr->name));
+
file_hdr->c_nlink = 1;
file_hdr->c_mode = FROM_OCTAL (tar_hdr->mode);
file_hdr->c_mode = file_hdr->c_mode & 07777;
@@ -398,7 +400,7 @@ read_in_tar_header (struct cpio_file_stat *file_hdr, int in_des)
case AREGTYPE:
/* Old tar format; if the last char in filename is '/' then it is
a directory, otherwise it's a regular file. */
- if (file_hdr->c_name[strlen (file_hdr->c_name) - 1] == '/')
+ if (file_hdr->c_name[file_hdr->c_namesize - 1] == '/')
file_hdr->c_mode |= CP_IFDIR;
else
file_hdr->c_mode |= CP_IFREG;
diff --git src/util.c src/util.c
index 6ff6032..4f3c073 100644
--- src/util.c
+++ src/util.c
@@ -1410,8 +1410,34 @@ set_file_times (int fd,
utime_error (name);
}
+
+void
+cpio_set_c_name (struct cpio_file_stat *file_hdr, char *name)
+{
+ static size_t buflen = 0;
+ size_t len = strlen (name) + 1;
+
+ if (buflen == 0)
+ {
+ buflen = len;
+ if (buflen < 32)
+ buflen = 32;
+ file_hdr->c_name = xmalloc (buflen);
+ }
+ else if (buflen < len)
+ {
+ buflen = len;
+ file_hdr->c_name = xrealloc (file_hdr->c_name, buflen);
+ }
+
+ file_hdr->c_namesize = len;
+ memmove (file_hdr->c_name, name, len);
+}
+
/* Do we have to ignore absolute paths, and if so, does the filename
- have an absolute path? */
+ have an absolute path? Before calling this function make sure that the
+ allocated NAME buffer has capacity at least 2 bytes. */
+
void
cpio_safer_name_suffix (char *name, bool link_target, bool absolute_names,
bool strip_leading_dots)
@@ -1426,6 +1452,10 @@ cpio_safer_name_suffix (char *name, bool link_target, bool absolute_names,
++p;
}
if (p != name)
+ /* The 'p' string is shortened version of 'name' with one exception; when
+ the 'name' points to an empty string (buffer where name[0] == '\0') the
+ 'p' then points to static string ".". So caller needs to ensure there
+ are at least two bytes available in 'name' buffer so memmove succeeds. */
memmove (name, p, (size_t)(strlen (p) + 1));
}
diff --git tests/inout.at tests/inout.at
index 60c3716..730cbd2 100644
--- tests/inout.at
+++ tests/inout.at
@@ -35,7 +35,22 @@ while read NAME LENGTH
do
genfile --length $LENGTH > $NAME
echo $NAME
-done < filelist |
- cpio --quiet -o > archive])
+done < filelist > filelist_raw
+
+for format in bin odc newc crc tar ustar hpbin hpodc
+do
+ cpio --format=$format --quiet -o < filelist_raw > archive.$format
+ rm -rf output
+ mkdir output && cd output
+ cpio -i --quiet < ../archive.$format
+
+ while read file
+ do
+ test -f $file || echo "$file not found"
+ done < ../filelist_raw
+
+ cd ..
+done
+])
AT_CLEANUP
--
2.20.1