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libsepol/backport-libsepol-cil-always-destroy-the-lexer-state.patch
yang_zhuang_zhuang dcbb3a6a58 fix heap-use-after-free in cil_yy_switch_to_buffer 
fix heap-use-after-free in __class_reset_perm_values()
  fix heap-buffer-overflow in cil_print_recursive_blockinherit
2021-03-15 11:31:23 +08:00

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From 90809674c13c03e324dff560654d0e686c5fc46b Mon Sep 17 00:00:00 2001
From: Evgeny Vereshchagin <evvers@ya.ru>
Date: Sun, 6 Dec 2020 23:29:22 +0100
Subject: [PATCH] libsepol/cil: always destroy the lexer state
It was found in https://github.com/google/oss-fuzz/pull/4790:
```
Invalid token '' at line 2 of fuzz
NEW_FUNC[1/2]: 0x67fff0 in yy_get_previous_state /src/selinux/libsepol/src/../cil/src/cil_lexer.c:1143
NEW_FUNC[2/2]: 0x6803e0 in yy_try_NUL_trans /src/selinux/libsepol/src/../cil/src/cil_lexer.c:1176
=================================================================
==12==ERROR: AddressSanitizer: heap-use-after-free on address 0x602000007992 at pc 0x000000681800 bp 0x7ffccddee530 sp 0x7ffccddee528
WRITE of size 1 at 0x602000007992 thread T0
SCARINESS: 41 (1-byte-write-heap-use-after-free)
#0 0x6817ff in cil_yy_switch_to_buffer /src/selinux/libsepol/src/../cil/src/cil_lexer.c:1315:17
#1 0x6820cc in cil_yy_scan_buffer /src/selinux/libsepol/src/../cil/src/cil_lexer.c:1571:2
#2 0x682662 in cil_lexer_setup /src/selinux/libsepol/src/../cil/src/cil_lexer.l:73:6
#3 0x5cf2ae in cil_parser /src/selinux/libsepol/src/../cil/src/cil_parser.c:220:2
#4 0x56d5e2 in cil_add_file /src/selinux/libsepol/src/../cil/src/cil.c:514:7
#5 0x556e91 in LLVMFuzzerTestOneInput /src/secilc-fuzzer.c:434:7
#6 0x459ab1 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:599:15
#7 0x45a755 in fuzzer::Fuzzer::TryDetectingAMemoryLeak(unsigned char const*, unsigned long, bool) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:675:3
#8 0x45acd9 in fuzzer::Fuzzer::MutateAndTestOne() /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:747:5
#9 0x45b875 in fuzzer::Fuzzer::Loop(std::__Fuzzer::vector<fuzzer::SizedFile, fuzzer::fuzzer_allocator<fuzzer::SizedFile> >&) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:883:5
#10 0x4499fb in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:906:6
#11 0x473a32 in main /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerMain.cpp:20:10
#12 0x7f982296d83f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2083f)
#13 0x41e758 in _start (/out/secilc-fuzzer+0x41e758)
DEDUP_TOKEN: cil_yy_switch_to_buffer--cil_yy_scan_buffer--cil_lexer_setup
0x602000007992 is located 2 bytes inside of 4-byte region [0x602000007990,0x602000007994)
freed by thread T0 here:
#0 0x521ef2 in free /src/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:127:3
#1 0x56d630 in cil_add_file /src/selinux/libsepol/src/../cil/src/cil.c:526:2
#2 0x556e91 in LLVMFuzzerTestOneInput /src/secilc-fuzzer.c:434:7
#3 0x459ab1 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:599:15
#4 0x458fba in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool, bool*) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:505:3
#5 0x45acc7 in fuzzer::Fuzzer::MutateAndTestOne() /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:745:19
#6 0x45b875 in fuzzer::Fuzzer::Loop(std::__Fuzzer::vector<fuzzer::SizedFile, fuzzer::fuzzer_allocator<fuzzer::SizedFile> >&) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:883:5
#7 0x4499fb in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:906:6
#8 0x473a32 in main /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerMain.cpp:20:10
#9 0x7f982296d83f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2083f)
DEDUP_TOKEN: free--cil_add_file--LLVMFuzzerTestOneInput
previously allocated by thread T0 here:
#0 0x52215d in malloc /src/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:145:3
#1 0x5cecb8 in cil_malloc /src/selinux/libsepol/src/../cil/src/cil_mem.c:39:14
#2 0x56d584 in cil_add_file /src/selinux/libsepol/src/../cil/src/cil.c:510:11
#3 0x556e91 in LLVMFuzzerTestOneInput /src/secilc-fuzzer.c:434:7
#4 0x459ab1 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:599:15
#5 0x458fba in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool, bool*) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:505:3
#6 0x45acc7 in fuzzer::Fuzzer::MutateAndTestOne() /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:745:19
#7 0x45b875 in fuzzer::Fuzzer::Loop(std::__Fuzzer::vector<fuzzer::SizedFile, fuzzer::fuzzer_allocator<fuzzer::SizedFile> >&) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:883:5
#8 0x4499fb in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:906:6
#9 0x473a32 in main /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerMain.cpp:20:10
#10 0x7f982296d83f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2083f)
DEDUP_TOKEN: malloc--cil_malloc--cil_add_file
SUMMARY: AddressSanitizer: heap-use-after-free /src/selinux/libsepol/src/../cil/src/cil_lexer.c:1315:17 in cil_yy_switch_to_buffer
Shadow bytes around the buggy address:
0x0c047fff8ee0: fa fa fd fa fa fa fd fd fa fa fd fa fa fa fd fd
0x0c047fff8ef0: fa fa fd fa fa fa fd fd fa fa fd fa fa fa fd fd
0x0c047fff8f00: fa fa fd fa fa fa fd fa fa fa fd fa fa fa fd fd
0x0c047fff8f10: fa fa fd fa fa fa fd fd fa fa fd fa fa fa fd fd
0x0c047fff8f20: fa fa fd fa fa fa fd fd fa fa fd fa fa fa fd fa
=>0x0c047fff8f30: fa fa[fd]fa fa fa fd fa fa fa fd fa fa fa fd fa
0x0c047fff8f40: fa fa fd fa fa fa fd fa fa fa fd fa fa fa fd fa
0x0c047fff8f50: fa fa fd fa fa fa fd fd fa fa fd fa fa fa fd fa
0x0c047fff8f60: fa fa fd fd fa fa fd fa fa fa fd fd fa fa fd fa
0x0c047fff8f70: fa fa 00 00 fa fa 02 fa fa fa 02 fa fa fa 00 fa
0x0c047fff8f80: fa fa 03 fa fa fa 00 fa fa fa 03 fa fa fa 00 fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
Shadow gap: cc
==12==ABORTING
```
Signed-off-by: Evgeny Vereshchagin <evvers@ya.ru>
Acked-by: Nicolas Iooss <nicolas.iooss@m4x.org>
---
libsepol/cil/src/cil_parser.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/libsepol/cil/src/cil_parser.c b/libsepol/cil/src/cil_parser.c
index 585ea7704..a8af1dce2 100644
--- a/libsepol/cil/src/cil_parser.c
+++ b/libsepol/cil/src/cil_parser.c
@@ -310,6 +310,7 @@ int cil_parser(char *_path, char *buffer, uint32_t size, struct cil_tree **parse
while (!cil_stack_is_empty(stack)) {
pop_hll_info(stack, &hll_lineno, &hll_expand);
}
+ cil_lexer_destroy();
cil_stack_destroy(&stack);
return SEPOL_ERR;
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