[OE-core] [PATCH] Fix for CVE-2014-6277 and CVE-2014-6278
Mark Hatle
mark.hatle at windriver.com
Thu Oct 2 14:42:36 UTC 2014
On 10/2/14, 9:28 AM, Sona Sarmadi wrote:
> This is a followup patch to incomplete CVE-2014-6271 fix code execution via
> specially-crafted environment.
>
> CVE-2014-6277: bash: untrusted pointer use issue leading to code execution
> CVE-2014-6278: bash: code execution via specially crafted environment variables
This is not actually the fix to the problem, but a mitigation to help prevent it
from being exploitable.
(The patch is fine, just want to make sure that the subject of the commit and
patch message are adjusted to match what it really is.)
--Mark
> Signed-off-by: Sona Sarmadi <sona.sarmadi at enea.com>
> ---
> .../bash-3.2.48/cve-2014-6277_cve-2014-6278.patch | 146 ++++++++++++++++++
> .../bash/bash/cve-2014-6277_cve-2014-6278.patch | 163 +++++++++++++++++++++
> meta/recipes-extended/bash/bash_3.2.48.bb | 1 +
> meta/recipes-extended/bash/bash_4.3.bb | 1 +
> 4 files changed, 311 insertions(+)
> create mode 100644 meta/recipes-extended/bash/bash-3.2.48/cve-2014-6277_cve-2014-6278.patch
> create mode 100644 meta/recipes-extended/bash/bash/cve-2014-6277_cve-2014-6278.patch
>
> diff --git a/meta/recipes-extended/bash/bash-3.2.48/cve-2014-6277_cve-2014-6278.patch b/meta/recipes-extended/bash/bash-3.2.48/cve-2014-6277_cve-2014-6278.patch
> new file mode 100644
> index 0000000..42b559a
> --- /dev/null
> +++ b/meta/recipes-extended/bash/bash-3.2.48/cve-2014-6277_cve-2014-6278.patch
> @@ -0,0 +1,146 @@
> +Fix for CVE-2014-6277 and CVE-2014-6278
> +
> +Bug-Reported-by: Florian Weimer <fweimer at redhat.com>
> +
> +Bug-Description:
> +
> +This patch changes the encoding bash uses for exported functions to avoid
> +clashes with shell variables and to avoid depending only on an environment
> +variable's contents to determine whether or not to interpret it as a shell
> +function.
> +
> +Upstream-Status: Backport {GNU Patch-ID: bash32-054}
> +
> +Signed-off-by: Sona Sarmadi <sona.sarmadi at enea.com>
> +---
> +--- a/variables.c 2014-09-16 19:10:39.000000000 -0400
> ++++ b/variables.c 2014-09-27 21:02:08.000000000 -0400
> +@@ -75,4 +75,9 @@
> + #define ifsname(s) ((s)[0] == 'I' && (s)[1] == 'F' && (s)[2] == 'S' && (s)[3] == '\0')
> +
> ++#define BASHFUNC_PREFIX "BASH_FUNC_"
> ++#define BASHFUNC_PREFLEN 10 /* == strlen(BASHFUNC_PREFIX */
> ++#define BASHFUNC_SUFFIX "%%"
> ++#define BASHFUNC_SUFFLEN 2 /* == strlen(BASHFUNC_SUFFIX) */
> ++
> + extern char **environ;
> +
> +@@ -242,5 +247,5 @@
> + static void dispose_temporary_env __P((sh_free_func_t *));
> +
> +-static inline char *mk_env_string __P((const char *, const char *));
> ++static inline char *mk_env_string __P((const char *, const char *, int));
> + static char **make_env_array_from_var_list __P((SHELL_VAR **));
> + static char **make_var_export_array __P((VAR_CONTEXT *));
> +@@ -310,19 +315,30 @@
> + /* If exported function, define it now. Don't import functions from
> + the environment in privileged mode. */
> +- if (privmode == 0 && read_but_dont_execute == 0 && STREQN ("() {", string, 4))
> ++ if (privmode == 0 && read_but_dont_execute == 0 &&
> ++ STREQN (BASHFUNC_PREFIX, name, BASHFUNC_PREFLEN) &&
> ++ STREQ (BASHFUNC_SUFFIX, name + char_index - BASHFUNC_SUFFLEN) &&
> ++ STREQN ("() {", string, 4))
> + {
> ++ size_t namelen;
> ++ char *tname; /* desired imported function name */
> ++
> ++ namelen = char_index - BASHFUNC_PREFLEN - BASHFUNC_SUFFLEN;
> ++
> ++ tname = name + BASHFUNC_PREFLEN; /* start of func name */
> ++ tname[namelen] = '\0'; /* now tname == func name */
> ++
> + string_length = strlen (string);
> +- temp_string = (char *)xmalloc (3 + string_length + char_index);
> ++ temp_string = (char *)xmalloc (namelen + string_length + 2);
> +
> +- strcpy (temp_string, name);
> +- temp_string[char_index] = ' ';
> +- strcpy (temp_string + char_index + 1, string);
> ++ memcpy (temp_string, tname, namelen);
> ++ temp_string[namelen] = ' ';
> ++ memcpy (temp_string + namelen + 1, string, string_length + 1);
> +
> + /* Don't import function names that are invalid identifiers from the
> + environment. */
> +- if (legal_identifier (name))
> +- parse_and_execute (temp_string, name, SEVAL_NONINT|SEVAL_NOHIST|SEVAL_FUNCDEF|SEVAL_ONECMD);
> ++ if (absolute_program (tname) == 0 && (posixly_correct == 0 || legal_identifier (tname)))
> ++ parse_and_execute (temp_string, tname, SEVAL_NONINT|SEVAL_NOHIST|SEVAL_FUNCDEF|SEVAL_ONECMD);
> +
> +- if (temp_var = find_function (name))
> ++ if (temp_var = find_function (tname))
> + {
> + VSETATTR (temp_var, (att_exported|att_imported));
> +@@ -330,5 +346,8 @@
> + }
> + else
> +- report_error (_("error importing function definition for `%s'"), name);
> ++ report_error (_("error importing function definition for `%s'"), tname);
> ++
> ++ /* Restore original suffix */
> ++ tname[namelen] = BASHFUNC_SUFFIX[0];
> + }
> + #if defined (ARRAY_VARS)
> +@@ -2208,5 +2227,5 @@
> +
> + INVALIDATE_EXPORTSTR (var);
> +- var->exportstr = mk_env_string (name, value);
> ++ var->exportstr = mk_env_string (name, value, 0);
> +
> + array_needs_making = 1;
> +@@ -2999,19 +3018,40 @@
> +
> + static inline char *
> +-mk_env_string (name, value)
> ++mk_env_string (name, value, isfunc)
> + const char *name, *value;
> ++ int isfunc;
> + {
> +- int name_len, value_len;
> +- char *p;
> ++ size_t name_len, value_len;
> ++ char *p, *q;
> +
> + name_len = strlen (name);
> + value_len = STRLEN (value);
> +- p = (char *)xmalloc (2 + name_len + value_len);
> +- strcpy (p, name);
> +- p[name_len] = '=';
> ++
> ++ /* If we are exporting a shell function, construct the encoded function
> ++ name. */
> ++ if (isfunc && value)
> ++ {
> ++ p = (char *)xmalloc (BASHFUNC_PREFLEN + name_len + BASHFUNC_SUFFLEN + value_len + 2);
> ++ q = p;
> ++ memcpy (q, BASHFUNC_PREFIX, BASHFUNC_PREFLEN);
> ++ q += BASHFUNC_PREFLEN;
> ++ memcpy (q, name, name_len);
> ++ q += name_len;
> ++ memcpy (q, BASHFUNC_SUFFIX, BASHFUNC_SUFFLEN);
> ++ q += BASHFUNC_SUFFLEN;
> ++ }
> ++ else
> ++ {
> ++ p = (char *)xmalloc (2 + name_len + value_len);
> ++ memcpy (p, name, name_len);
> ++ q = p + name_len;
> ++ }
> ++
> ++ q[0] = '=';
> + if (value && *value)
> +- strcpy (p + name_len + 1, value);
> ++ memcpy (q + 1, value, value_len + 1);
> + else
> +- p[name_len + 1] = '\0';
> ++ q[1] = '\0';
> ++
> + return (p);
> + }
> +@@ -3088,5 +3128,5 @@
> + using the cached exportstr... */
> + list[list_index] = USE_EXPORTSTR ? savestring (value)
> +- : mk_env_string (var->name, value);
> ++ : mk_env_string (var->name, value, function_p (var));
> +
> + if (USE_EXPORTSTR == 0)
> diff --git a/meta/recipes-extended/bash/bash/cve-2014-6277_cve-2014-6278.patch b/meta/recipes-extended/bash/bash/cve-2014-6277_cve-2014-6278.patch
> new file mode 100644
> index 0000000..d346f25
> --- /dev/null
> +++ b/meta/recipes-extended/bash/bash/cve-2014-6277_cve-2014-6278.patch
> @@ -0,0 +1,163 @@
> +Fix for CVE-2014-6277 and CVE-2014-6278
> +
> +Bug-Reported-by: Florian Weimer <fweimer at redhat.com>
> +
> +Bug-Description:
> +
> +This patch changes the encoding bash uses for exported functions to avoid
> +clashes with shell variables and to avoid depending only on an environment
> +variable's contents to determine whether or not to interpret it as a shell
> +function.
> +
> +Upstream-Status: Backport {GNU Patch-ID: bash43-027}
> +
> +Signed-off-by: Sona Sarmadi <sona.sarmadi at enea.com>
> +---
> +diff -ruN a/variables.c b/variables.c
> +--- a/variables.c 2014-09-30 10:21:12.481674914 +0200
> ++++ b/variables.c 2014-09-30 10:21:40.820459492 +0200
> +@@ -83,6 +83,11 @@
> +
> + #define ifsname(s) ((s)[0] == 'I' && (s)[1] == 'F' && (s)[2] == 'S' && (s)[3] == '\0')
> +
> ++#define BASHFUNC_PREFIX "BASH_FUNC_"
> ++#define BASHFUNC_PREFLEN 10 /* == strlen(BASHFUNC_PREFIX */
> ++#define BASHFUNC_SUFFIX "%%"
> ++#define BASHFUNC_SUFFLEN 2 /* == strlen(BASHFUNC_SUFFIX) */
> ++
> + extern char **environ;
> +
> + /* Variables used here and defined in other files. */
> +@@ -279,7 +284,7 @@
> + static void propagate_temp_var __P((PTR_T));
> + static void dispose_temporary_env __P((sh_free_func_t *));
> +
> +-static inline char *mk_env_string __P((const char *, const char *));
> ++static inline char *mk_env_string __P((const char *, const char *, int));
> + static char **make_env_array_from_var_list __P((SHELL_VAR **));
> + static char **make_var_export_array __P((VAR_CONTEXT *));
> + static char **make_func_export_array __P((void));
> +@@ -349,22 +354,33 @@
> +
> + /* If exported function, define it now. Don't import functions from
> + the environment in privileged mode. */
> +- if (privmode == 0 && read_but_dont_execute == 0 && STREQN ("() {", string, 4))
> ++ if (privmode == 0 && read_but_dont_execute == 0 &&
> ++ STREQN (BASHFUNC_PREFIX, name, BASHFUNC_PREFLEN) &&
> ++ STREQ (BASHFUNC_SUFFIX, name + char_index - BASHFUNC_SUFFLEN) &&
> ++ STREQN ("() {", string, 4))
> + {
> ++ size_t namelen;
> ++ char *tname; /* desired imported function name */
> ++
> ++ namelen = char_index - BASHFUNC_PREFLEN - BASHFUNC_SUFFLEN;
> ++
> ++ tname = name + BASHFUNC_PREFLEN; /* start of func name */
> ++ tname[namelen] = '\0'; /* now tname == func name */
> ++
> + string_length = strlen (string);
> +- temp_string = (char *)xmalloc (3 + string_length + char_index);
> ++ temp_string = (char *)xmalloc (namelen + string_length + 2);
> +
> +- strcpy (temp_string, name);
> +- temp_string[char_index] = ' ';
> +- strcpy (temp_string + char_index + 1, string);
> ++ memcpy (temp_string, tname, namelen);
> ++ temp_string[namelen] = ' ';
> ++ memcpy (temp_string + namelen + 1, string, string_length + 1);
> +
> + /* Don't import function names that are invalid identifiers from the
> + environment, though we still allow them to be defined as shell
> + variables. */
> +- if (legal_identifier (name))
> +- parse_and_execute (temp_string, name, SEVAL_NONINT|SEVAL_NOHIST|SEVAL_FUNCDEF|SEVAL_ONECMD);
> ++ if (absolute_program (tname) == 0 && (posixly_correct == 0 || legal_identifier (tname)))
> ++ parse_and_execute (temp_string, tname, SEVAL_NONINT|SEVAL_NOHIST|SEVAL_FUNCDEF|SEVAL_ONECMD);
> +
> +- if (temp_var = find_function (name))
> ++ if (temp_var = find_function (tname))
> + {
> + VSETATTR (temp_var, (att_exported|att_imported));
> + array_needs_making = 1;
> +@@ -377,8 +393,11 @@
> + array_needs_making = 1;
> + }
> + last_command_exit_value = 1;
> +- report_error (_("error importing function definition for `%s'"), name);
> ++ report_error (_("error importing function definition for `%s'"), tname);
> + }
> ++
> ++ /* Restore original suffix */
> ++ tname[namelen] = BASHFUNC_SUFFIX[0];
> + }
> + #if defined (ARRAY_VARS)
> + # if ARRAY_EXPORT
> +@@ -2957,7 +2976,7 @@
> + var->context = variable_context; /* XXX */
> +
> + INVALIDATE_EXPORTSTR (var);
> +- var->exportstr = mk_env_string (name, value);
> ++ var->exportstr = mk_env_string (name, value, 0);
> +
> + array_needs_making = 1;
> +
> +@@ -3855,21 +3874,42 @@
> + /* **************************************************************** */
> +
> + static inline char *
> +-mk_env_string (name, value)
> ++mk_env_string (name, value, isfunc)
> + const char *name, *value;
> ++ int isfunc;
> + {
> +- int name_len, value_len;
> +- char *p;
> ++ size_t name_len, value_len;
> ++ char *p, *q;
> +
> + name_len = strlen (name);
> + value_len = STRLEN (value);
> +- p = (char *)xmalloc (2 + name_len + value_len);
> +- strcpy (p, name);
> +- p[name_len] = '=';
> ++
> ++ /* If we are exporting a shell function, construct the encoded function
> ++ name. */
> ++ if (isfunc && value)
> ++ {
> ++ p = (char *)xmalloc (BASHFUNC_PREFLEN + name_len + BASHFUNC_SUFFLEN + value_len + 2);
> ++ q = p;
> ++ memcpy (q, BASHFUNC_PREFIX, BASHFUNC_PREFLEN);
> ++ q += BASHFUNC_PREFLEN;
> ++ memcpy (q, name, name_len);
> ++ q += name_len;
> ++ memcpy (q, BASHFUNC_SUFFIX, BASHFUNC_SUFFLEN);
> ++ q += BASHFUNC_SUFFLEN;
> ++ }
> ++ else
> ++ {
> ++ p = (char *)xmalloc (2 + name_len + value_len);
> ++ memcpy (p, name, name_len);
> ++ q = p + name_len;
> ++ }
> ++
> ++ q[0] = '=';
> + if (value && *value)
> +- strcpy (p + name_len + 1, value);
> ++ memcpy (q + 1, value, value_len + 1);
> + else
> +- p[name_len + 1] = '\0';
> ++ q[1] = '\0';
> ++
> + return (p);
> + }
> +
> +@@ -3955,7 +3995,7 @@
> + /* Gee, I'd like to get away with not using savestring() if we're
> + using the cached exportstr... */
> + list[list_index] = USE_EXPORTSTR ? savestring (value)
> +- : mk_env_string (var->name, value);
> ++ : mk_env_string (var->name, value, function_p (var));
> +
> + if (USE_EXPORTSTR == 0)
> + SAVE_EXPORTSTR (var, list[list_index]);
> diff --git a/meta/recipes-extended/bash/bash_3.2.48.bb b/meta/recipes-extended/bash/bash_3.2.48.bb
> index e6a04cd..94c81a4 100644
> --- a/meta/recipes-extended/bash/bash_3.2.48.bb
> +++ b/meta/recipes-extended/bash/bash_3.2.48.bb
> @@ -14,6 +14,7 @@ SRC_URI = "${GNU_MIRROR}/bash/bash-${PV}.tar.gz;name=tarball \
> file://test-output.patch \
> file://cve-2014-6271.patch;striplevel=0 \
> file://cve-2014-7169.patch \
> + file://cve-2014-6277_cve-2014-6278.patch \
> file://run-ptest \
> "
>
> diff --git a/meta/recipes-extended/bash/bash_4.3.bb b/meta/recipes-extended/bash/bash_4.3.bb
> index 69ddecc..915be68 100644
> --- a/meta/recipes-extended/bash/bash_4.3.bb
> +++ b/meta/recipes-extended/bash/bash_4.3.bb
> @@ -11,6 +11,7 @@ SRC_URI = "${GNU_MIRROR}/bash/${BPN}-${PV}.tar.gz;name=tarball \
> file://test-output.patch \
> file://cve-2014-6271.patch;striplevel=0 \
> file://cve-2014-7169.patch \
> + file://cve-2014-6277_cve-2014-6278.patch \
> file://run-ptest \
> "
>
>
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