C library hygiene: Use symbol prefixes as a namespace mechanism to mitigate the risk of clashes #2
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bradbishop
pushed a commit
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this issue
Apr 19, 2023
Fix up an off-by-one error in the test suite. I modified the test to
instead report more sensors than were present in the message buffer and
received the following from ASAN:
```
=================================================================
==297936==ERROR: AddressSanitizer: stack-buffer-overflow on address 0xffffc18300b9 at pc 0xffffa04cae2c bp 0xffffc182fe40 sp 0xffffc182fe58
READ of size 1 at 0xffffc18300b9 thread T0
#0 0xffffa04cae28 in pldm_msgbuf_extract_uint8 ../src/msgbuf/../msgbuf.h:129
#1 0xffffa04cae28 in decode_get_state_sensor_readings_resp ../src/platform.c:804
#2 0x2c0278 in GetStateSensorReadings_testBadDecodeResponse_Test::TestBody() ../tests/libpldm_platform_test.cpp:843
#3 0xffffa03ba0f8 in void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) (/lib64/libgtest.so.1.12.1+0x4a0f8)
#4 0xffffa03a6680 in testing::Test::Run() (/lib64/libgtest.so.1.12.1+0x36680)
#5 0xffffa03a688c in testing::TestInfo::Run() (/lib64/libgtest.so.1.12.1+0x3688c)
#6 0xffffa03a6c30 in testing::TestSuite::Run() (/lib64/libgtest.so.1.12.1+0x36c30)
#7 0xffffa03b2dd0 in testing::internal::UnitTestImpl::RunAllTests() (/lib64/libgtest.so.1.12.1+0x42dd0)
#8 0xffffa03b1998 in testing::UnitTest::Run() (/lib64/libgtest.so.1.12.1+0x41998)
#9 0xffffa0400940 in main (/lib64/libgtest_main.so.1.12.1+0x940)
#10 0xffff9f80b584 in __libc_start_call_main (/lib64/libc.so.6+0x2b584)
#11 0xffff9f80b65c in __libc_start_main@@GLIBC_2.34 (/lib64/libc.so.6+0x2b65c)
#12 0x2b2a6c in _start (/mnt/host/andrew/src/openbmc/libpldm/build/tests/libpldm_platform_test+0x2b2a6c)
Address 0xffffc18300b9 is located in stack of thread T0 at offset 297 in frame
#0 0x2bfe90 in GetStateSensorReadings_testBadDecodeResponse_Test::TestBody() ../tests/libpldm_platform_test.cpp:811
This frame has 14 object(s):
[48, 49) 'retcompletion_code' (line 831)
[64, 65) 'retcomp_sensorCnt' (line 832)
[80, 84) 'rc' (line 819)
[96, 100) '<unknown>'
[112, 116) 'stateField' (line 827)
[128, 132) 'retstateField' (line 833)
[144, 148) '<unknown>'
[160, 168) '<unknown>'
[192, 200) '<unknown>'
[224, 232) '<unknown>'
[256, 264) '<unknown>'
[288, 297) 'responseMsg' (line 815) <== Memory access at offset 297 overflows this variable
[320, 336) 'gtest_ar' (line 822)
[352, 368) 'gtest_ar' (line 847)
HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork
(longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow ../src/msgbuf/../msgbuf.h:129 in pldm_msgbuf_extract_uint8
Shadow bytes around the buggy address:
0x200ff8305fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ff8305fd0: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
0x200ff8305fe0: 00 00 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
0x200ff8305ff0: 00 00 f1 f1 f1 f1 f1 f1 01 f2 01 f2 04 f2 f8 f2
0x200ff8306000: 04 f2 04 f2 04 f2 00 f2 f2 f2 00 f2 f2 f2 00 f2
=>0x200ff8306010: f2 f2 00 f2 f2 f2 00[01]f2 f2 f8 f8 f2 f2 00 00
0x200ff8306020: f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ff8306030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ff8306040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ff8306050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ff8306060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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
==297936==ABORTING
```
Signed-off-by: Andrew Jeffery <[email protected]>
Change-Id: Ib63254bd345d28924aee47eb230bcbea0c88811a
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libpldm exposes many encode, decode and utility functions as part of its API, but none of them are prefixed to prevent symbol clashes in applications that link against more libraries than just libpldm. For instance, some utility symbols exported by the library include
crc8(),crc32()and others.This violates the best practices suggestion from Good Practices in Library Design, Implementation, and Maintenance:
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