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eeafde1351
When running secilc on the following CIL file, the program tries to free
the data associated with type X using cil_destroy_typeattribute():
(macro sys_obj_type ((user ARG1)) (typeattribute X))
(block B
(type X)
(call sys_obj_type (Y))
)
By adding some printf statements to cil_typeattribute_init(),
cil_type_init() and cil_destroy_typeattribute(), the error message I get
when using gcc's address sanitizer is:
$ secilc -o /dev/null -f /dev/null test.cil -vvvvvv
creating TYPE 0x60400000dfd0
Parsing 2017-02-02_crashing_nulptrderef_cil.cil
Building AST from Parse Tree
creating TYPEATTR 0x60600000e420
creating TYPE 0x60400000df50
Destroying Parse Tree
Resolving AST
Failed to resolve call statement at 2017-02-02_crashing_nulptrderef_cil.cil:5
Problem at 2017-02-02_crashing_nulptrderef_cil.cil:5
Pass 8 of resolution failed
Failed to resolve ast
Failed to compile cildb: -2
Destroying TYPEATTR 0x60600000e420, types (nil) name X
Destroying TYPEATTR 0x60400000df50, types 0xbebebebe00000000 name X
ASAN:DEADLYSIGNAL
=================================================================
==30684==ERROR: AddressSanitizer: SEGV on unknown address
0x000000000000 (pc 0x7fc0539d114a bp 0x7ffc1fbcb300 sp
0x7ffc1fbcb2f0 T0)
#0 0x7fc0539d1149 in ebitmap_destroy /usr/src/selinux/libsepol/src/ebitmap.c:356
#1 0x7fc053b96201 in cil_destroy_typeattribute ../cil/src/cil_build_ast.c:2370
#2 0x7fc053b42ea4 in cil_destroy_data ../cil/src/cil.c:616
#3 0x7fc053c595bf in cil_tree_node_destroy ../cil/src/cil_tree.c:235
#4 0x7fc053c59819 in cil_tree_children_destroy ../cil/src/cil_tree.c:201
#5 0x7fc053c59958 in cil_tree_subtree_destroy ../cil/src/cil_tree.c:172
#6 0x7fc053c59a27 in cil_tree_destroy ../cil/src/cil_tree.c:165
#7 0x7fc053b44fd7 in cil_db_destroy ../cil/src/cil.c:299
#8 0x4026a1 in main /usr/src/selinux/secilc/secilc.c:335
#9 0x7fc0535e5290 in __libc_start_main (/usr/lib/libc.so.6+0x20290)
#10 0x403af9 in _start (/usr/src/selinux/DESTDIR/usr/bin/secilc+0x403af9)
AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /usr/src/selinux/libsepol/src/ebitmap.c:356 in ebitmap_destroy
==30684==ABORTING
When copying the AST tree in cil_resolve_call1(),
__cil_copy_node_helper() calls cil_copy_typeattribute() to grab type X
in the symbol table of block B, and creates a node with the data of X
but with CIL_TYPEATTRIBUTE flavor.
This example is a "type confusion" bug between cil_type and
cil_typeattribute structures. It can be generalized to any couple of
structures sharing the same symbol table (an easy way of finding other
couples is by reading the code of cil_flavor_to_symtab_index()).
Fix this issue in a "generic" way in __cil_copy_node_helper(), by
verifying that the flavor of the found data is the same as expected and
triggering an error when it is not.
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
|
||
|---|---|---|
| checkpolicy | ||
| dbus | ||
| gui | ||
| libselinux | ||
| libsemanage | ||
| libsepol | ||
| mcstrans | ||
| policycoreutils | ||
| python | ||
| restorecond | ||
| sandbox | ||
| scripts | ||
| secilc | ||
| semodule-utils | ||
| .gitignore | ||
| CleanSpec.mk | ||
| Makefile | ||
| README | ||
Please submit all bug reports and patches to selinux@tycho.nsa.gov. Subscribe via selinux-join@tycho.nsa.gov. Build dependencies on Fedora: yum install audit-libs-devel bison bzip2-devel dbus-devel dbus-glib-devel flex flex-devel flex-static glib2-devel libcap-devel libcap-ng-devel pam-devel pcre-devel python-devel setools-devel swig xmlto redhat-rpm-config To build and install everything under a private directory, run: make DESTDIR=~/obj install install-pywrap To install as the default system libraries and binaries (overwriting any previously installed ones - dangerous!), on x86_64, run: make LIBDIR=/usr/lib64 SHLIBDIR=/lib64 install install-pywrap relabel or on x86 (32-bit), run: make install install-pywrap relabel This may render your system unusable if the upstream SELinux userspace lacks library functions or other dependencies relied upon by your distribution. If it breaks, you get to keep both pieces. To install libsepol on macOS (mainly for policy analysis): cd libsepol; make DESTDIR=/usr/local PREFIX=/usr/local install This requires GNU coreutils (brew install coreutils).