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df6bde031b
As is, this sanity check doesn't seem to be testing fdelt_chk, because passing a value of "0" to FD_SET wont cause the compiler to insert any calls to fdelt_chk(). The documentation is a little misleading. If we actually triggered fdelt_chk at runtime, bitcoind would abort. I think this check would be better replaced (if possible) by additional checks in security-check.py. The compiler may insert a call to fdelt_warn() (aliased with fdelt_chk in glibc) at compile time if it can determine that an invalid value is being passed to FD_SET. These checks are essentially; value < 0 or value >= FD_SETSIZE along with a check for wether the value is a compile time constant. If the compiler can determine an invalid value is being passed, a call to fdelt_warn will be inserted. Passing 0 should never cause a call to be inserted. You can check this after compiling: ```bash objdump -dC bitcoind | grep sanity_fdelt ... 0000000000399d20 <sanity_test_fdelt()>: 399d20: 48 81 ec 98 00 00 00 sub $0x98,%rsp 399d27: b9 10 00 00 00 mov $0x10,%ecx 399d2c: 64 48 8b 04 25 28 00 mov %fs:0x28,%rax 399d33: 00 00 399d35: 48 89 84 24 88 00 00 mov %rax,0x88(%rsp) 399d3c: 00 399d3d: 31 c0 xor %eax,%eax 399d3f: 48 89 e7 mov %rsp,%rdi 399d42: fc cld 399d43: f3 48 ab rep stos %rax,%es:(%rdi) 399d46: 48 8b 84 24 88 00 00 mov 0x88(%rsp),%rax 399d4d: 00 399d4e: 64 48 33 04 25 28 00 xor %fs:0x28,%rax 399d55: 00 00 399d57: 75 0d jne 399d66 <sanity_test_fdelt()+0x46> 399d59: b8 01 00 00 00 mov $0x1,%eax 399d5e: 48 81 c4 98 00 00 00 add $0x98,%rsp 399d65: c3 retq 399d66: e8 85 df c8 ff callq 27cf0 <__stack_chk_fail@plt> 399d6b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) ``` To test, you could modify this test to pass -1 to FD_SET, and check that a call to fdelt_warn() is inserted, and that running bitcoind fails. i.e: ```bash 0000000000399d20 <sanity_test_fdelt()>: 399d20: 48 81 ec 98 00 00 00 sub $0x98,%rsp 399d27: b9 10 00 00 00 mov $0x10,%ecx 399d2c: 64 48 8b 04 25 28 00 mov %fs:0x28,%rax 399d33: 00 00 399d35: 48 89 84 24 88 00 00 mov %rax,0x88(%rsp) 399d3c: 00 399d3d: 31 c0 xor %eax,%eax 399d3f: 48 89 e7 mov %rsp,%rdi 399d42: fc cld 399d43: f3 48 ab rep stos %rax,%es:(%rdi) 399d46: 48 c7 c7 ff ff ff ff mov $0xffffffffffffffff,%rdi 399d4d: e8 3e ff ff ff callq 399c90 <__fdelt_warn> 399d52: 0f b6 04 24 movzbl (%rsp),%eax 399d56: 83 e0 01 and $0x1,%eax 399d59: 48 8b 94 24 88 00 00 mov 0x88(%rsp),%rdx 399d60: 00 399d61: 64 48 33 14 25 28 00 xor %fs:0x28,%rdx 399d68: 00 00 399d6a: 75 08 jne 399d74 <sanity_test_fdelt()+0x54> 399d6c: 48 81 c4 98 00 00 00 add $0x98,%rsp 399d73: c3 retq 399d74: e8 77 df c8 ff callq 27cf0 <__stack_chk_fail@plt> 399d79: 0f 1f 80 00 00 00 00 nopl 0x0(%rax) ``` ```bash ./src/bitcoind *** buffer overflow detected ***: src/bitcoind terminated Aborted ```
46 lines
1.2 KiB
C++
46 lines
1.2 KiB
C++
// Copyright (c) 2009-2019 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#if defined(HAVE_CONFIG_H)
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#include <config/bitcoin-config.h>
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#endif
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#include <cstddef>
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extern "C" void* memcpy(void* a, const void* b, size_t c);
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void* memcpy_int(void* a, const void* b, size_t c)
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{
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return memcpy(a, b, c);
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}
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namespace
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{
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// trigger: Use the memcpy_int wrapper which calls our internal memcpy.
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// A direct call to memcpy may be optimized away by the compiler.
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// test: Fill an array with a sequence of integers. memcpy to a new empty array.
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// Verify that the arrays are equal. Use an odd size to decrease the odds of
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// the call being optimized away.
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template <unsigned int T>
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bool sanity_test_memcpy()
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{
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unsigned int memcpy_test[T];
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unsigned int memcpy_verify[T] = {};
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for (unsigned int i = 0; i != T; ++i)
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memcpy_test[i] = i;
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memcpy_int(memcpy_verify, memcpy_test, sizeof(memcpy_test));
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for (unsigned int i = 0; i != T; ++i) {
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if (memcpy_verify[i] != i)
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return false;
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}
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return true;
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}
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} // namespace
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bool glibc_sanity_test()
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{
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return sanity_test_memcpy<1025>();
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}
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