https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90222
Bug ID: 90222
Summary: Speculative execution data leak
Product: gcc
Version: 6.4.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: venkateshprabu at gmail dot com
Target Milestone: ---
File:
aarch64-gnu-linux/usr/include/c++/6.4.1/aarch64-gnu-linux/bits/ctype_inline.h
Speculative execution data leak
An attacker might be able to read the process' memory.
In std::ctype<char>::scan_is(unsigned short, char const *, char const *):
Accessing memory based on a speculative out-of-bounds access. (CWE-200)
Coverity report:
37namespace std _GLIBCXX_VISIBILITY(default)
38{
39_GLIBCXX_BEGIN_NAMESPACE_VERSION
40
41 bool
42 ctype<char>::
43 is(mask __m, char __c) const
44 { return _M_table[static_cast<unsigned char>(__c)] & __m; }
45
46 const char*
47 ctype<char>::
48 is(const char* __low, const char* __high, mask* __vec) const
49 {
50 while (__low < __high)
CID 8654704: Nested memory access
(AUDIT.SPECULATIVE_EXECUTION_DATA_LEAK) [select issue]
51 *__vec++ = _M_table[static_cast<unsigned char>(*__low++)];
52 return __high;
53 }
54
55 const char*
56 ctype<char>::
57 scan_is(mask __m, const char* __low, const char* __high) const
58 {
1. compare_value: Comparing __low in __low < __high.
2. Condition __low < __high, taking true branch.
3. compared_memory_access: Using compared value __low to access memory
in *__low, yielding a potentially sensitive 1-byte value.
CID 8655024 (#1 of 1): Speculative execution data leak
(AUDIT.SPECULATIVE_EXECUTION_DATA_LEAK)
4. sensitive_memory_access: Using sensitive value static_cast<unsigned
char>(*__low) to access memory in this->_M_table[static_cast<unsigned
char>(*__low)].
Insert a barrier, such as the lfence instruction, between the
comparison and the memory accesses to prevent speculative execution.
59 while (__low < __high
60 && !(_M_table[static_cast<unsigned char>(*__low)] & __m))
61 ++__low;
62 return __low;
63 }
64
65 const char*
66 ctype<char>::
67 scan_not(mask __m, const char* __low, const char* __high) const
68 {
CID 8654818: Speculative execution data leak
(AUDIT.SPECULATIVE_EXECUTION_DATA_LEAK) [select issue]
69 while (__low < __high
70 && (_M_table[static_cast<unsigned char>(*__low)] & __m) != 0)
71 ++__low;
72 return __low;
73 }
74
75_GLIBCXX_END_NAMESPACE_VERSION
76} // namespace
