libsepol: Security fix CVE-2021-36084

Source: https://github.com/SELinuxProject/selinux
MR: 111851
Type: Security Fix
Disposition: Backport from https://github.com/SELinuxProject/selinux/commit/f34d3d30c8325e4847a6b696fe7a3936a8a361f3
ChangeID: 7fae27568e26ccbb18be3d2a1ce7332d42706f18
Description:

Affects: libsepol < 3.2

Signed-off-by: Armin Kuster <akuster@mvista.com>
Signed-off-by: Joe MacDonald <joe@deserted.net>

2 files changed, 101 insertions, 0 deletions

diff --git a/recipes-security/selinux/libsepol/CVE-2021-36084.patch b/recipes-security/selinux/libsepol/CVE-2021-36084.patch
new file mode 100644
index 0000000..1001563
--- /dev/null
+++ b/recipes-security/selinux/libsepol/CVE-2021-36084.patch
@@ -0,0 +1,99 @@
+From f34d3d30c8325e4847a6b696fe7a3936a8a361f3 Mon Sep 17 00:00:00 2001
+From: James Carter <jwcart2@gmail.com>
+Date: Thu, 8 Apr 2021 13:32:01 -0400
+Subject: [PATCH] libsepol/cil: Destroy classperms list when resetting
+ classpermission
+
+Nicolas Iooss reports:
+  A few months ago, OSS-Fuzz found a crash in the CIL compiler, which
+  got reported as
+  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=28648 (the title
+  is misleading, or is caused by another issue that conflicts with the
+  one I report in this message). Here is a minimized CIL policy which
+  reproduces the issue:
+
+  (class CLASS (PERM))
+  (classorder (CLASS))
+  (sid SID)
+  (sidorder (SID))
+  (user USER)
+  (role ROLE)
+  (type TYPE)
+  (category CAT)
+  (categoryorder (CAT))
+  (sensitivity SENS)
+  (sensitivityorder (SENS))
+  (sensitivitycategory SENS (CAT))
+  (allow TYPE self (CLASS (PERM)))
+  (roletype ROLE TYPE)
+  (userrole USER ROLE)
+  (userlevel USER (SENS))
+  (userrange USER ((SENS)(SENS (CAT))))
+  (sidcontext SID (USER ROLE TYPE ((SENS)(SENS))))
+
+  (classpermission CLAPERM)
+
+  (optional OPT
+      (roletype nonexistingrole nonexistingtype)
+      (classpermissionset CLAPERM (CLASS (PERM)))
+  )
+
+  The CIL policy fuzzer (which mimics secilc built with clang Address
+  Sanitizer) reports:
+
+  ==36541==ERROR: AddressSanitizer: heap-use-after-free on address
+  0x603000004f98 at pc 0x56445134c842 bp 0x7ffe2a256590 sp
+  0x7ffe2a256588
+  READ of size 8 at 0x603000004f98 thread T0
+      #0 0x56445134c841 in __cil_verify_classperms
+  /selinux/libsepol/src/../cil/src/cil_verify.c:1620:8
+      #1 0x56445134a43e in __cil_verify_classpermission
+  /selinux/libsepol/src/../cil/src/cil_verify.c:1650:9
+      #2 0x56445134a43e in __cil_pre_verify_helper
+  /selinux/libsepol/src/../cil/src/cil_verify.c:1715:8
+      #3 0x5644513225ac in cil_tree_walk_core
+  /selinux/libsepol/src/../cil/src/cil_tree.c:272:9
+      #4 0x564451322ab1 in cil_tree_walk
+  /selinux/libsepol/src/../cil/src/cil_tree.c:316:7
+      #5 0x5644513226af in cil_tree_walk_core
+  /selinux/libsepol/src/../cil/src/cil_tree.c:284:9
+      #6 0x564451322ab1 in cil_tree_walk
+  /selinux/libsepol/src/../cil/src/cil_tree.c:316:7
+      #7 0x5644512b88fd in cil_pre_verify
+  /selinux/libsepol/src/../cil/src/cil_post.c:2510:7
+      #8 0x5644512b88fd in cil_post_process
+  /selinux/libsepol/src/../cil/src/cil_post.c:2524:7
+      #9 0x5644511856ff in cil_compile
+  /selinux/libsepol/src/../cil/src/cil.c:564:7
+
+The classperms list of a classpermission rule is created and filled
+in when classpermissionset rules are processed, so it doesn't own any
+part of the list and shouldn't retain any of it when it is reset.
+
+Destroy the classperms list (without destroying the data in it)  when
+resetting a classpermission rule.
+
+Reported-by: Nicolas Iooss <nicolas.iooss@m4x.org>
+Signed-off-by: James Carter <jwcart2@gmail.com>
+
+Upstream-Status: Backport
+CVE: CVE-2021-36084
+Signed-off-by: Armin Kuster <akuster@mvista.com>
+
+---
+ libsepol/cil/src/cil_reset_ast.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+Index: libsepol-3.0/cil/src/cil_reset_ast.c
+===================================================================
+--- libsepol-3.0.orig/cil/src/cil_reset_ast.c
++++ libsepol-3.0/cil/src/cil_reset_ast.c
+@@ -52,7 +52,7 @@ static void cil_reset_classpermission(st
+                return;
+        }
+ 
+-       cil_reset_classperms_list(cp->classperms);
++       cil_list_destroy(&cp->classperms, CIL_FALSE);
+ }
+ 
+ static void cil_reset_classperms_set(struct cil_classperms_set *cp_set)
diff --git a/recipes-security/selinux/libsepol_3.2.bb b/recipes-security/selinux/libsepol_3.2.bb
index 48d5f49..6215d24 100644
--- a/recipes-security/selinux/libsepol_3.2.bb
+++ b/recipes-security/selinux/libsepol_3.2.bb
@@ -9,6 +9,8 @@ LIC_FILES_CHKSUM = "file://${S}/COPYING;md5=a6f89e2100d9b6cdffcea4f398e37343"
 
 require selinux_common.inc
 
+SRC_URI += "file://CVE-2021-36084.patch"
+
 inherit lib_package
 
 S = "${WORKDIR}/git/libsepol"