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author | fanquake <fanquake@gmail.com> | 2020-05-04 08:19:44 +0800 |
---|---|---|
committer | fanquake <fanquake@gmail.com> | 2020-05-07 15:45:09 +0800 |
commit | df6bde031b24112abf3a94337a2c096698acde6e (patch) | |
tree | 29357cb3c4e262ab4d188694f764ef5e9535c6b6 /src/compat/glibc_sanity.cpp | |
parent | 8bf1540cc235fb8fb5330a7ae8ab638247ceb177 (diff) | |
download | bitcoin-df6bde031b24112abf3a94337a2c096698acde6e.tar.xz |
test: remove glibc fdelt sanity check
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
```
Diffstat (limited to 'src/compat/glibc_sanity.cpp')
-rw-r--r-- | src/compat/glibc_sanity.cpp | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/src/compat/glibc_sanity.cpp b/src/compat/glibc_sanity.cpp index cc74f28899..0367b9a53f 100644 --- a/src/compat/glibc_sanity.cpp +++ b/src/compat/glibc_sanity.cpp @@ -8,10 +8,6 @@ #include <cstddef> -#if defined(HAVE_SYS_SELECT_H) -bool sanity_test_fdelt(); -#endif - extern "C" void* memcpy(void* a, const void* b, size_t c); void* memcpy_int(void* a, const void* b, size_t c) { @@ -45,9 +41,5 @@ bool sanity_test_memcpy() bool glibc_sanity_test() { -#if defined(HAVE_SYS_SELECT_H) - if (!sanity_test_fdelt()) - return false; -#endif return sanity_test_memcpy<1025>(); } |