From: Armin Kuster <[email protected]> Source: https://gitlab.freedesktop.org/dbu MR: 108825 Type: Security Fix Disposition: Backport from https://gitlab.freedesktop.org/dbus/dbus/-/commit/e75c67a28fa2bc41a8ab0de433a52355c71a8abf ChangeID: dea9518b9c13dab66e7d553c622000b9c6e268cc Description:
Affects: < 1.12.20 Signed-off-by: Armin Kuster <[email protected]> --- .../dbus/dbus/CVE-2020-35512.patch | 301 ++++++++++++++++++ meta/recipes-core/dbus/dbus_1.12.16.bb | 1 + 2 files changed, 302 insertions(+) create mode 100644 meta/recipes-core/dbus/dbus/CVE-2020-35512.patch diff --git a/meta/recipes-core/dbus/dbus/CVE-2020-35512.patch b/meta/recipes-core/dbus/dbus/CVE-2020-35512.patch new file mode 100644 index 0000000000..27f5d58675 --- /dev/null +++ b/meta/recipes-core/dbus/dbus/CVE-2020-35512.patch @@ -0,0 +1,301 @@ +From 2b7948ef907669e844b52c4fa2268d6e3162a70c Mon Sep 17 00:00:00 2001 +From: Simon McVittie <[email protected]> +Date: Tue, 30 Jun 2020 19:29:06 +0100 +Subject: [PATCH] userdb: Reference-count DBusUserInfo, DBusGroupInfo + +Previously, the hash table indexed by uid (or gid) took ownership of the +single reference to the heap-allocated struct, and the hash table +indexed by username (or group name) had a borrowed pointer to the same +struct that exists in the other hash table. + +However, this can break down if you have two or more distinct usernames +that share a numeric identifier. This is generally a bad idea, because +the user-space model in such situations does not match the kernel-space +reality, and in particular there is no effective kernel-level security +boundary between such users, but it is sometimes done anyway. + +In this case, when the second username is looked up in the userdb, it +overwrites (replaces) the entry in the hash table that is indexed by +uid, freeing the DBusUserInfo. This results in both the key and the +value in the hash table that is indexed by username becoming dangling +pointers (use-after-free), leading to undefined behaviour, which is +certainly not what we want to see when doing access control. + +An equivalent situation can occur with groups, in the rare case where +a numeric group ID has two names (although I have not heard of this +being done in practice). + +Solve this by reference-counting the data structure. There are up to +three references in practice: one held temporarily while the lookup +function is populating and storing it, one held by the hash table that +is indexed by uid, and one held by the hash table that is indexed by +name. + +Closes: dbus#305 +Signed-off-by: Simon McVittie <[email protected]> + +Upsteam-Status: Backport +https://gitlab.freedesktop.org/dbus/dbus/-/commit/e75c67a28fa2bc41a8ab0de433a52355c71a8abf +CVE: CVE-2020-35512 +Signed-off-by: Armin Kuster <[email protected]> + +--- + dbus/dbus-sysdeps-unix.h | 2 ++ + dbus/dbus-userdb-util.c | 38 ++++++++++++++++++----- + dbus/dbus-userdb.c | 67 ++++++++++++++++++++++++++++++---------- + dbus/dbus-userdb.h | 6 ++-- + 4 files changed, 86 insertions(+), 27 deletions(-) + +Index: dbus-1.12.16/dbus/dbus-sysdeps-unix.h +=================================================================== +--- dbus-1.12.16.orig/dbus/dbus-sysdeps-unix.h ++++ dbus-1.12.16/dbus/dbus-sysdeps-unix.h +@@ -105,6 +105,7 @@ typedef struct DBusGroupInfo DBusGroupIn + */ + struct DBusUserInfo + { ++ size_t refcount; /**< Reference count */ + dbus_uid_t uid; /**< UID */ + dbus_gid_t primary_gid; /**< GID */ + dbus_gid_t *group_ids; /**< Groups IDs, *including* above primary group */ +@@ -118,6 +119,7 @@ struct DBusUserInfo + */ + struct DBusGroupInfo + { ++ size_t refcount; /**< Reference count */ + dbus_gid_t gid; /**< GID */ + char *groupname; /**< Group name */ + }; +Index: dbus-1.12.16/dbus/dbus-userdb-util.c +=================================================================== +--- dbus-1.12.16.orig/dbus/dbus-userdb-util.c ++++ dbus-1.12.16/dbus/dbus-userdb-util.c +@@ -38,6 +38,15 @@ + * @{ + */ + ++static DBusGroupInfo * ++_dbus_group_info_ref (DBusGroupInfo *info) ++{ ++ _dbus_assert (info->refcount > 0); ++ _dbus_assert (info->refcount < SIZE_MAX); ++ info->refcount++; ++ return info; ++} ++ + /** + * Checks to see if the UID sent in is the console user + * +@@ -240,9 +249,9 @@ _dbus_get_user_id_and_primary_group (con + * @param gid the group ID or #DBUS_GID_UNSET + * @param groupname group name or #NULL + * @param error error to fill in +- * @returns the entry in the database ++ * @returns the entry in the database (borrowed, do not free) + */ +-DBusGroupInfo* ++const DBusGroupInfo* + _dbus_user_database_lookup_group (DBusUserDatabase *db, + dbus_gid_t gid, + const DBusString *groupname, +@@ -287,13 +296,14 @@ _dbus_user_database_lookup_group (DBusUs + dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL); + return NULL; + } ++ info->refcount = 1; + + if (gid != DBUS_GID_UNSET) + { + if (!_dbus_group_info_fill_gid (info, gid, error)) + { + _DBUS_ASSERT_ERROR_IS_SET (error); +- _dbus_group_info_free_allocated (info); ++ _dbus_group_info_unref (info); + return NULL; + } + } +@@ -302,7 +312,7 @@ _dbus_user_database_lookup_group (DBusUs + if (!_dbus_group_info_fill (info, groupname, error)) + { + _DBUS_ASSERT_ERROR_IS_SET (error); +- _dbus_group_info_free_allocated (info); ++ _dbus_group_info_unref (info); + return NULL; + } + } +@@ -314,7 +324,7 @@ _dbus_user_database_lookup_group (DBusUs + if (!_dbus_hash_table_insert_uintptr (db->groups, info->gid, info)) + { + dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL); +- _dbus_group_info_free_allocated (info); ++ _dbus_group_info_unref (info); + return NULL; + } + +Index: dbus-1.12.16/dbus/dbus-userdb.c +=================================================================== +--- dbus-1.12.16.orig/dbus/dbus-userdb.c ++++ dbus-1.12.16/dbus/dbus-userdb.c +@@ -35,34 +35,57 @@ + * @{ + */ + ++static DBusUserInfo * ++_dbus_user_info_ref (DBusUserInfo *info) ++{ ++ _dbus_assert (info->refcount > 0); ++ _dbus_assert (info->refcount < SIZE_MAX); ++ info->refcount++; ++ return info; ++} ++ + /** +- * Frees the given #DBusUserInfo's members with _dbus_user_info_free() ++ * Decrements the reference count. If it reaches 0, ++ * frees the given #DBusUserInfo's members with _dbus_user_info_free() + * and also calls dbus_free() on the block itself + * + * @param info the info + */ + void +-_dbus_user_info_free_allocated (DBusUserInfo *info) ++_dbus_user_info_unref (DBusUserInfo *info) + { + if (info == NULL) /* hash table will pass NULL */ + return; + ++ _dbus_assert (info->refcount > 0); ++ _dbus_assert (info->refcount < SIZE_MAX); ++ ++ if (--info->refcount > 0) ++ return; ++ + _dbus_user_info_free (info); + dbus_free (info); + } + + /** +- * Frees the given #DBusGroupInfo's members with _dbus_group_info_free() ++ * Decrements the reference count. If it reaches 0, ++ * frees the given #DBusGroupInfo's members with _dbus_group_info_free() + * and also calls dbus_free() on the block itself + * + * @param info the info + */ + void +-_dbus_group_info_free_allocated (DBusGroupInfo *info) ++_dbus_group_info_unref (DBusGroupInfo *info) + { + if (info == NULL) /* hash table will pass NULL */ + return; + ++ _dbus_assert (info->refcount > 0); ++ _dbus_assert (info->refcount < SIZE_MAX); ++ ++ if (--info->refcount > 0) ++ return; ++ + _dbus_group_info_free (info); + dbus_free (info); + } +@@ -124,7 +147,7 @@ _dbus_is_a_number (const DBusString *str + * @param error error to fill in + * @returns the entry in the database + */ +-DBusUserInfo* ++const DBusUserInfo* + _dbus_user_database_lookup (DBusUserDatabase *db, + dbus_uid_t uid, + const DBusString *username, +@@ -170,13 +193,14 @@ _dbus_user_database_lookup (DBusUserData + dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL); + return NULL; + } ++ info->refcount = 1; + + if (uid != DBUS_UID_UNSET) + { + if (!_dbus_user_info_fill_uid (info, uid, error)) + { + _DBUS_ASSERT_ERROR_IS_SET (error); +- _dbus_user_info_free_allocated (info); ++ _dbus_user_info_unref (info); + return NULL; + } + } +@@ -185,7 +209,7 @@ _dbus_user_database_lookup (DBusUserData + if (!_dbus_user_info_fill (info, username, error)) + { + _DBUS_ASSERT_ERROR_IS_SET (error); +- _dbus_user_info_free_allocated (info); ++ _dbus_user_info_unref (info); + return NULL; + } + } +@@ -198,7 +222,7 @@ _dbus_user_database_lookup (DBusUserData + if (!_dbus_hash_table_insert_uintptr (db->users, info->uid, info)) + { + dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL); +- _dbus_user_info_free_allocated (info); ++ _dbus_user_info_unref(info); + return NULL; + } + +@@ -568,24 +592,24 @@ _dbus_user_database_new (void) + db->refcount = 1; + + db->users = _dbus_hash_table_new (DBUS_HASH_UINTPTR, +- NULL, (DBusFreeFunction) _dbus_user_info_free_allocated); ++ NULL, (DBusFreeFunction) _dbus_user_info_unref); + + if (db->users == NULL) + goto failed; + + db->groups = _dbus_hash_table_new (DBUS_HASH_UINTPTR, +- NULL, (DBusFreeFunction) _dbus_group_info_free_allocated); ++ NULL, (DBusFreeFunction) _dbus_group_info_unref); + + if (db->groups == NULL) + goto failed; + + db->users_by_name = _dbus_hash_table_new (DBUS_HASH_STRING, +- NULL, NULL); ++ NULL, (DBusFreeFunction) _dbus_user_info_unref); + if (db->users_by_name == NULL) + goto failed; + + db->groups_by_name = _dbus_hash_table_new (DBUS_HASH_STRING, +- NULL, NULL); ++ NULL, (DBusFreeFunction) _dbus_group_info_unref); + if (db->groups_by_name == NULL) + goto failed; + +Index: dbus-1.12.16/dbus/dbus-userdb.h +=================================================================== +--- dbus-1.12.16.orig/dbus/dbus-userdb.h ++++ dbus-1.12.16/dbus/dbus-userdb.h +@@ -76,19 +76,19 @@ dbus_bool_t _dbus_user_database_ge + DBusError *error); + + DBUS_PRIVATE_EXPORT +-DBusUserInfo* _dbus_user_database_lookup (DBusUserDatabase *db, ++const DBusUserInfo* _dbus_user_database_lookup (DBusUserDatabase *db, + dbus_uid_t uid, + const DBusString *username, + DBusError *error); + DBUS_PRIVATE_EXPORT +-DBusGroupInfo* _dbus_user_database_lookup_group (DBusUserDatabase *db, ++const DBusGroupInfo* _dbus_user_database_lookup_group (DBusUserDatabase *db, + dbus_gid_t gid, + const DBusString *groupname, + DBusError *error); ++ ++void _dbus_user_info_unref (DBusUserInfo *info); + DBUS_PRIVATE_EXPORT +-void _dbus_user_info_free_allocated (DBusUserInfo *info); +-DBUS_PRIVATE_EXPORT +-void _dbus_group_info_free_allocated (DBusGroupInfo *info); ++void _dbus_group_info_unref (DBusGroupInfo *info); + #endif /* DBUS_USERDB_INCLUDES_PRIVATE */ + + DBUS_PRIVATE_EXPORT diff --git a/meta/recipes-core/dbus/dbus_1.12.16.bb b/meta/recipes-core/dbus/dbus_1.12.16.bb index 10d1b34448..13d453eb32 100644 --- a/meta/recipes-core/dbus/dbus_1.12.16.bb +++ b/meta/recipes-core/dbus/dbus_1.12.16.bb @@ -17,6 +17,7 @@ SRC_URI = "https://dbus.freedesktop.org/releases/dbus/dbus-${PV}.tar.gz \ file://dbus-1.init \ file://clear-guid_from_server-if-send_negotiate_unix_f.patch \ file://CVE-2020-12049.patch \ + file://CVE-2020-35512.patch \ " SRC_URI[md5sum] = "2dbeae80dfc9e3632320c6a53d5e8890" -- 2.25.1
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