[Buildroot] [PATCH 1/1] package/cpio: fix CVE-2021-38185
Yann E. MORIN
yann.morin.1998 at free.fr
Fri Aug 20 08:10:07 UTC 2021
Fabrice, All,
On 2021-08-19 23:46 +0200, Fabrice Fontaine spake thusly:
> GNU cpio through 2.13 allows attackers to execute arbitrary code via a
> crafted pattern file, because of a dstring.c ds_fgetstr integer overflow
> that triggers an out-of-bounds heap write. NOTE: it is unclear whether
> there are common cases where the pattern file, associated with the -E
> option, is untrusted data.
>
> Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
Applied to master, thanks.
Regards,
Yann E. MORIN.
> ---
> .../0002-Rewrite-dynamic-string-support.patch | 461 ++++++++++++++++++
> package/cpio/0003-Fix-previous-commit.patch | 40 ++
> package/cpio/cpio.mk | 4 +
> 3 files changed, 505 insertions(+)
> create mode 100644 package/cpio/0002-Rewrite-dynamic-string-support.patch
> create mode 100644 package/cpio/0003-Fix-previous-commit.patch
>
> diff --git a/package/cpio/0002-Rewrite-dynamic-string-support.patch b/package/cpio/0002-Rewrite-dynamic-string-support.patch
> new file mode 100644
> index 0000000000..44282ae3f1
> --- /dev/null
> +++ b/package/cpio/0002-Rewrite-dynamic-string-support.patch
> @@ -0,0 +1,461 @@
> +From dd96882877721703e19272fe25034560b794061b Mon Sep 17 00:00:00 2001
> +From: Sergey Poznyakoff <gray at gnu.org>
> +Date: Sat, 7 Aug 2021 12:52:21 +0300
> +Subject: Rewrite dynamic string support.
> +
> +* src/dstring.c (ds_init): Take a single argument.
> +(ds_free): New function.
> +(ds_resize): Take a single argument. Use x2nrealloc to expand
> +the storage.
> +(ds_reset,ds_append,ds_concat,ds_endswith): New function.
> +(ds_fgetstr): Rewrite. In particular, this fixes integer overflow.
> +* src/dstring.h (dynamic_string): Keep both the allocated length
> +(ds_size) and index of the next free byte in the string (ds_idx).
> +(ds_init,ds_resize): Change signature.
> +(ds_len): New macro.
> +(ds_free,ds_reset,ds_append,ds_concat,ds_endswith): New protos.
> +* src/copyin.c: Use new ds_ functions.
> +* src/copyout.c: Likewise.
> +* src/copypass.c: Likewise.
> +* src/util.c: Likewise.
> +
> +[Retrieved from:
> +https://git.savannah.gnu.org/cgit/cpio.git/commit/?id=dd96882877721703e19272fe25034560b794061b]
> +Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
> +---
> + src/copyin.c | 40 +++++++++++++-------------
> + src/copyout.c | 16 ++++-------
> + src/copypass.c | 34 +++++++++++------------
> + src/dstring.c | 88 ++++++++++++++++++++++++++++++++++++++++++----------------
> + src/dstring.h | 31 ++++++++++-----------
> + src/util.c | 6 ++--
> + 6 files changed, 123 insertions(+), 92 deletions(-)
> +
> +diff --git a/src/copyin.c b/src/copyin.c
> +index a096048..4fb14af 100644
> +--- a/src/copyin.c
> ++++ b/src/copyin.c
> +@@ -55,11 +55,12 @@ query_rename(struct cpio_file_stat* file_hdr, FILE *tty_in, FILE *tty_out,
> + char *str_res; /* Result for string function. */
> + static dynamic_string new_name; /* New file name for rename option. */
> + static int initialized_new_name = false;
> ++
> + if (!initialized_new_name)
> +- {
> +- ds_init (&new_name, 128);
> +- initialized_new_name = true;
> +- }
> ++ {
> ++ ds_init (&new_name);
> ++ initialized_new_name = true;
> ++ }
> +
> + if (rename_flag)
> + {
> +@@ -780,37 +781,36 @@ long_format (struct cpio_file_stat *file_hdr, char const *link_name)
> + already in `save_patterns' (from the command line) are preserved. */
> +
> + static void
> +-read_pattern_file ()
> ++read_pattern_file (void)
> + {
> +- int max_new_patterns;
> +- char **new_save_patterns;
> +- int new_num_patterns;
> ++ char **new_save_patterns = NULL;
> ++ size_t max_new_patterns;
> ++ size_t new_num_patterns;
> + int i;
> +- dynamic_string pattern_name;
> ++ dynamic_string pattern_name = DYNAMIC_STRING_INITIALIZER;
> + FILE *pattern_fp;
> +
> + if (num_patterns < 0)
> + num_patterns = 0;
> +- max_new_patterns = 1 + num_patterns;
> +- new_save_patterns = (char **) xmalloc (max_new_patterns * sizeof (char *));
> + new_num_patterns = num_patterns;
> +- ds_init (&pattern_name, 128);
> ++ max_new_patterns = num_patterns;
> ++ new_save_patterns = xcalloc (max_new_patterns, sizeof (new_save_patterns[0]));
> +
> + pattern_fp = fopen (pattern_file_name, "r");
> + if (pattern_fp == NULL)
> + open_fatal (pattern_file_name);
> + while (ds_fgetstr (pattern_fp, &pattern_name, '\n') != NULL)
> + {
> +- if (new_num_patterns >= max_new_patterns)
> +- {
> +- max_new_patterns += 1;
> +- new_save_patterns = (char **)
> +- xrealloc ((char *) new_save_patterns,
> +- max_new_patterns * sizeof (char *));
> +- }
> ++ if (new_num_patterns == max_new_patterns)
> ++ new_save_patterns = x2nrealloc (new_save_patterns,
> ++ &max_new_patterns,
> ++ sizeof (new_save_patterns[0]));
> + new_save_patterns[new_num_patterns] = xstrdup (pattern_name.ds_string);
> + ++new_num_patterns;
> + }
> ++
> ++ ds_free (&pattern_name);
> ++
> + if (ferror (pattern_fp) || fclose (pattern_fp) == EOF)
> + close_error (pattern_file_name);
> +
> +@@ -1210,7 +1210,7 @@ swab_array (char *ptr, int count)
> + in the file system. */
> +
> + void
> +-process_copy_in ()
> ++process_copy_in (void)
> + {
> + FILE *tty_in = NULL; /* Interactive file for rename option. */
> + FILE *tty_out = NULL; /* Interactive file for rename option. */
> +diff --git a/src/copyout.c b/src/copyout.c
> +index 5ca587f..ca6798c 100644
> +--- a/src/copyout.c
> ++++ b/src/copyout.c
> +@@ -594,9 +594,10 @@ assign_string (char **pvar, char *value)
> + The format of the header depends on the compatibility (-c) flag. */
> +
> + void
> +-process_copy_out ()
> ++process_copy_out (void)
> + {
> +- dynamic_string input_name; /* Name of file read from stdin. */
> ++ dynamic_string input_name = DYNAMIC_STRING_INITIALIZER;
> ++ /* Name of file read from stdin. */
> + struct stat file_stat; /* Stat record for file. */
> + struct cpio_file_stat file_hdr = CPIO_FILE_STAT_INITIALIZER;
> + /* Output header information. */
> +@@ -605,7 +606,6 @@ process_copy_out ()
> + char *orig_file_name = NULL;
> +
> + /* Initialize the copy out. */
> +- ds_init (&input_name, 128);
> + file_hdr.c_magic = 070707;
> +
> + /* Check whether the output file might be a tape. */
> +@@ -657,14 +657,9 @@ process_copy_out ()
> + {
> + if (file_hdr.c_mode & CP_IFDIR)
> + {
> +- int len = strlen (input_name.ds_string);
> + /* Make sure the name ends with a slash */
> +- if (input_name.ds_string[len-1] != '/')
> +- {
> +- ds_resize (&input_name, len + 2);
> +- input_name.ds_string[len] = '/';
> +- input_name.ds_string[len+1] = 0;
> +- }
> ++ if (!ds_endswith (&input_name, '/'))
> ++ ds_append (&input_name, '/');
> + }
> + }
> +
> +@@ -875,6 +870,7 @@ process_copy_out ()
> + (unsigned long) blocks), (unsigned long) blocks);
> + }
> + cpio_file_stat_free (&file_hdr);
> ++ ds_free (&input_name);
> + }
> +
> +
> +diff --git a/src/copypass.c b/src/copypass.c
> +index 5d5e939..23ee687 100644
> +--- a/src/copypass.c
> ++++ b/src/copypass.c
> +@@ -48,10 +48,12 @@ set_copypass_perms (int fd, const char *name, struct stat *st)
> + If `link_flag', link instead of copying. */
> +
> + void
> +-process_copy_pass ()
> ++process_copy_pass (void)
> + {
> +- dynamic_string input_name; /* Name of file from stdin. */
> +- dynamic_string output_name; /* Name of new file. */
> ++ dynamic_string input_name = DYNAMIC_STRING_INITIALIZER;
> ++ /* Name of file from stdin. */
> ++ dynamic_string output_name = DYNAMIC_STRING_INITIALIZER;
> ++ /* Name of new file. */
> + size_t dirname_len; /* Length of `directory_name'. */
> + int res; /* Result of functions. */
> + char *slash; /* For moving past slashes in input name. */
> +@@ -65,25 +67,18 @@ process_copy_pass ()
> + created files */
> +
> + /* Initialize the copy pass. */
> +- ds_init (&input_name, 128);
> +
> + dirname_len = strlen (directory_name);
> + if (change_directory_option && !ISSLASH (directory_name[0]))
> + {
> + char *pwd = xgetcwd ();
> +-
> +- dirname_len += strlen (pwd) + 1;
> +- ds_init (&output_name, dirname_len + 2);
> +- strcpy (output_name.ds_string, pwd);
> +- strcat (output_name.ds_string, "/");
> +- strcat (output_name.ds_string, directory_name);
> ++
> ++ ds_concat (&output_name, pwd);
> ++ ds_append (&output_name, '/');
> + }
> +- else
> +- {
> +- ds_init (&output_name, dirname_len + 2);
> +- strcpy (output_name.ds_string, directory_name);
> +- }
> +- output_name.ds_string[dirname_len] = '/';
> ++ ds_concat (&output_name, directory_name);
> ++ ds_append (&output_name, '/');
> ++ dirname_len = ds_len (&output_name);
> + output_is_seekable = true;
> +
> + change_dir ();
> +@@ -116,8 +111,8 @@ process_copy_pass ()
> + /* Make the name of the new file. */
> + for (slash = input_name.ds_string; *slash == '/'; ++slash)
> + ;
> +- ds_resize (&output_name, dirname_len + strlen (slash) + 2);
> +- strcpy (output_name.ds_string + dirname_len + 1, slash);
> ++ ds_reset (&output_name, dirname_len);
> ++ ds_concat (&output_name, slash);
> +
> + existing_dir = false;
> + if (lstat (output_name.ds_string, &out_file_stat) == 0)
> +@@ -333,6 +328,9 @@ process_copy_pass ()
> + (unsigned long) blocks),
> + (unsigned long) blocks);
> + }
> ++
> ++ ds_free (&input_name);
> ++ ds_free (&output_name);
> + }
> +
> + /* Try and create a hard link from FILE_NAME to another file
> +diff --git a/src/dstring.c b/src/dstring.c
> +index b261d5a..692d3e7 100644
> +--- a/src/dstring.c
> ++++ b/src/dstring.c
> +@@ -20,8 +20,8 @@
> + #if defined(HAVE_CONFIG_H)
> + # include <config.h>
> + #endif
> +-
> + #include <stdio.h>
> ++#include <stdlib.h>
> + #if defined(HAVE_STRING_H) || defined(STDC_HEADERS)
> + #include <string.h>
> + #else
> +@@ -33,24 +33,41 @@
> + /* Initialiaze dynamic string STRING with space for SIZE characters. */
> +
> + void
> +-ds_init (dynamic_string *string, int size)
> ++ds_init (dynamic_string *string)
> ++{
> ++ memset (string, 0, sizeof *string);
> ++}
> ++
> ++/* Free the dynamic string storage. */
> ++
> ++void
> ++ds_free (dynamic_string *string)
> + {
> +- string->ds_length = size;
> +- string->ds_string = (char *) xmalloc (size);
> ++ free (string->ds_string);
> + }
> +
> +-/* Expand dynamic string STRING, if necessary, to hold SIZE characters. */
> ++/* Expand dynamic string STRING, if necessary. */
> +
> + void
> +-ds_resize (dynamic_string *string, int size)
> ++ds_resize (dynamic_string *string)
> + {
> +- if (size > string->ds_length)
> ++ if (string->ds_idx == string->ds_size)
> + {
> +- string->ds_length = size;
> +- string->ds_string = (char *) xrealloc ((char *) string->ds_string, size);
> ++ string->ds_string = x2nrealloc (string->ds_string, &string->ds_size,
> ++ 1);
> + }
> + }
> +
> ++/* Reset the index of the dynamic string S to LEN. */
> ++
> ++void
> ++ds_reset (dynamic_string *s, size_t len)
> ++{
> ++ while (len > s->ds_size)
> ++ ds_resize (s);
> ++ s->ds_idx = len;
> ++}
> ++
> + /* Dynamic string S gets a string terminated by the EOS character
> + (which is removed) from file F. S will increase
> + in size during the function if the string from F is longer than
> +@@ -61,34 +78,50 @@ ds_resize (dynamic_string *string, int size)
> + char *
> + ds_fgetstr (FILE *f, dynamic_string *s, char eos)
> + {
> +- int insize; /* Amount needed for line. */
> +- int strsize; /* Amount allocated for S. */
> + int next_ch;
> +
> + /* Initialize. */
> +- insize = 0;
> +- strsize = s->ds_length;
> ++ s->ds_idx = 0;
> +
> + /* Read the input string. */
> +- next_ch = getc (f);
> +- while (next_ch != eos && next_ch != EOF)
> ++ while ((next_ch = getc (f)) != eos && next_ch != EOF)
> + {
> +- if (insize >= strsize - 1)
> +- {
> +- ds_resize (s, strsize * 2 + 2);
> +- strsize = s->ds_length;
> +- }
> +- s->ds_string[insize++] = next_ch;
> +- next_ch = getc (f);
> ++ ds_resize (s);
> ++ s->ds_string[s->ds_idx++] = next_ch;
> + }
> +- s->ds_string[insize++] = '\0';
> ++ ds_resize (s);
> ++ s->ds_string[s->ds_idx] = '\0';
> +
> +- if (insize == 1 && next_ch == EOF)
> ++ if (s->ds_idx == 0 && next_ch == EOF)
> + return NULL;
> + else
> + return s->ds_string;
> + }
> +
> ++void
> ++ds_append (dynamic_string *s, int c)
> ++{
> ++ ds_resize (s);
> ++ s->ds_string[s->ds_idx] = c;
> ++ if (c)
> ++ {
> ++ s->ds_idx++;
> ++ ds_resize (s);
> ++ s->ds_string[s->ds_idx] = 0;
> ++ }
> ++}
> ++
> ++void
> ++ds_concat (dynamic_string *s, char const *str)
> ++{
> ++ size_t len = strlen (str);
> ++ while (len + 1 > s->ds_size)
> ++ ds_resize (s);
> ++ memcpy (s->ds_string + s->ds_idx, str, len);
> ++ s->ds_idx += len;
> ++ s->ds_string[s->ds_idx] = 0;
> ++}
> ++
> + char *
> + ds_fgets (FILE *f, dynamic_string *s)
> + {
> +@@ -100,3 +133,10 @@ ds_fgetname (FILE *f, dynamic_string *s)
> + {
> + return ds_fgetstr (f, s, '\0');
> + }
> ++
> ++/* Return true if the dynamic string S ends with character C. */
> ++int
> ++ds_endswith (dynamic_string *s, int c)
> ++{
> ++ return (s->ds_idx > 0 && s->ds_string[s->ds_idx - 1] == c);
> ++}
> +diff --git a/src/dstring.h b/src/dstring.h
> +index 5d24181..ca7a5f1 100644
> +--- a/src/dstring.h
> ++++ b/src/dstring.h
> +@@ -17,10 +17,6 @@
> + Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
> + Boston, MA 02110-1301 USA. */
> +
> +-#ifndef NULL
> +-#define NULL 0
> +-#endif
> +-
> + /* A dynamic string consists of record that records the size of an
> + allocated string and the pointer to that string. The actual string
> + is a normal zero byte terminated string that can be used with the
> +@@ -30,22 +26,25 @@
> +
> + typedef struct
> + {
> +- int ds_length; /* Actual amount of storage allocated. */
> +- char *ds_string; /* String. */
> ++ size_t ds_size; /* Actual amount of storage allocated. */
> ++ size_t ds_idx; /* Index of the next free byte in the string. */
> ++ char *ds_string; /* String storage. */
> + } dynamic_string;
> +
> ++#define DYNAMIC_STRING_INITIALIZER { 0, 0, NULL }
> +
> +-/* Macros that look similar to the original string functions.
> +- WARNING: These macros work only on pointers to dynamic string records.
> +- If used with a real record, an "&" must be used to get the pointer. */
> +-#define ds_strlen(s) strlen ((s)->ds_string)
> +-#define ds_strcmp(s1, s2) strcmp ((s1)->ds_string, (s2)->ds_string)
> +-#define ds_strncmp(s1, s2, n) strncmp ((s1)->ds_string, (s2)->ds_string, n)
> +-#define ds_index(s, c) index ((s)->ds_string, c)
> +-#define ds_rindex(s, c) rindex ((s)->ds_string, c)
> ++void ds_init (dynamic_string *string);
> ++void ds_free (dynamic_string *string);
> ++void ds_reset (dynamic_string *s, size_t len);
> +
> +-void ds_init (dynamic_string *string, int size);
> +-void ds_resize (dynamic_string *string, int size);
> ++/* All functions below guarantee that s->ds_string[s->ds_idx] == '\0' */
> + char *ds_fgetname (FILE *f, dynamic_string *s);
> + char *ds_fgets (FILE *f, dynamic_string *s);
> + char *ds_fgetstr (FILE *f, dynamic_string *s, char eos);
> ++void ds_append (dynamic_string *s, int c);
> ++void ds_concat (dynamic_string *s, char const *str);
> ++
> ++#define ds_len(s) ((s)->ds_idx)
> ++
> ++int ds_endswith (dynamic_string *s, int c);
> ++
> +diff --git a/src/util.c b/src/util.c
> +index 996d4fa..ff2746d 100644
> +--- a/src/util.c
> ++++ b/src/util.c
> +@@ -846,11 +846,9 @@ get_next_reel (int tape_des)
> + FILE *tty_out; /* File for interacting with user. */
> + int old_tape_des;
> + char *next_archive_name;
> +- dynamic_string new_name;
> ++ dynamic_string new_name = DYNAMIC_STRING_INITIALIZER;
> + char *str_res;
> +
> +- ds_init (&new_name, 128);
> +-
> + /* Open files for interactive communication. */
> + tty_in = fopen (TTY_NAME, "r");
> + if (tty_in == NULL)
> +@@ -925,7 +923,7 @@ get_next_reel (int tape_des)
> + error (PAXEXIT_FAILURE, 0, _("internal error: tape descriptor changed from %d to %d"),
> + old_tape_des, tape_des);
> +
> +- free (new_name.ds_string);
> ++ ds_free (&new_name);
> + fclose (tty_in);
> + fclose (tty_out);
> + }
> +--
> +cgit v1.2.1
> +
> diff --git a/package/cpio/0003-Fix-previous-commit.patch b/package/cpio/0003-Fix-previous-commit.patch
> new file mode 100644
> index 0000000000..e33a8523d8
> --- /dev/null
> +++ b/package/cpio/0003-Fix-previous-commit.patch
> @@ -0,0 +1,40 @@
> +From dfc801c44a93bed7b3951905b188823d6a0432c8 Mon Sep 17 00:00:00 2001
> +From: Sergey Poznyakoff <gray at gnu.org>
> +Date: Wed, 11 Aug 2021 18:10:38 +0300
> +Subject: Fix previous commit
> +
> +* src/dstring.c (ds_reset,ds_concat): Don't call ds_resize in a
> +loop.
> +
> +[Retrieved from:
> +https://git.savannah.gnu.org/cgit/cpio.git/commit/?id=dfc801c44a93bed7b3951905b188823d6a0432c8]
> +Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
> +---
> + src/dstring.c | 4 ++--
> + 1 file changed, 2 insertions(+), 2 deletions(-)
> +
> +diff --git a/src/dstring.c b/src/dstring.c
> +index 692d3e7..b7e0bb5 100644
> +--- a/src/dstring.c
> ++++ b/src/dstring.c
> +@@ -64,7 +64,7 @@ void
> + ds_reset (dynamic_string *s, size_t len)
> + {
> + while (len > s->ds_size)
> +- ds_resize (s);
> ++ s->ds_string = x2nrealloc (s->ds_string, &s->ds_size, 1);
> + s->ds_idx = len;
> + }
> +
> +@@ -116,7 +116,7 @@ ds_concat (dynamic_string *s, char const *str)
> + {
> + size_t len = strlen (str);
> + while (len + 1 > s->ds_size)
> +- ds_resize (s);
> ++ s->ds_string = x2nrealloc (s->ds_string, &s->ds_size, 1);
> + memcpy (s->ds_string + s->ds_idx, str, len);
> + s->ds_idx += len;
> + s->ds_string[s->ds_idx] = 0;
> +--
> +cgit v1.2.1
> +
> diff --git a/package/cpio/cpio.mk b/package/cpio/cpio.mk
> index 9ce281dd1c..e95ea742b3 100644
> --- a/package/cpio/cpio.mk
> +++ b/package/cpio/cpio.mk
> @@ -12,6 +12,10 @@ CPIO_LICENSE = GPL-3.0+
> CPIO_LICENSE_FILES = COPYING
> CPIO_CPE_ID_VENDOR = gnu
>
> +# 0002-Rewrite-dynamic-string-support.patch
> +# 0003-Fix-previous-commit.patch
> +CPIO_IGNORE_CVES += CVE-2021-38185
> +
> # cpio uses argp.h which is not provided by uclibc or musl by default.
> # Use the argp-standalone package to provide this.
> ifeq ($(BR2_PACKAGE_ARGP_STANDALONE),y)
> --
> 2.30.2
>
> _______________________________________________
> buildroot mailing list
> buildroot at busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot
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