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Fix the overrun issue reported by static application security testing #177

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Fix the overrun issue reported by static application security testing #177

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15 changes: 8 additions & 7 deletions snappy_test_tool.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -77,11 +77,12 @@ namespace {
class DataEndingAtUnreadablePage {
public:
explicit DataEndingAtUnreadablePage(const std::string& s) {
const size_t page_size = sysconf(_SC_PAGESIZE);
long page_size = sysconf(_SC_PAGESIZE);
page_size_ = (size_t)(page_size < 0 ? 4096 : page_size);
const size_t size = s.size();
// Round up space for string to a multiple of page_size.
size_t space_for_string = (size + page_size - 1) & ~(page_size - 1);
alloc_size_ = space_for_string + page_size;
// Round up space for string to a multiple of page_size_.
size_t space_for_string = (size + page_size_ - 1) & ~(page_size_ - 1);
alloc_size_ = space_for_string + page_size_;
mem_ = mmap(NULL, alloc_size_,
PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
CHECK_NE(MAP_FAILED, mem_);
Expand All @@ -91,13 +92,12 @@ class DataEndingAtUnreadablePage {
data_ = dst;
size_ = size;
// Make guard page unreadable.
CHECK_EQ(0, mprotect(protected_page_, page_size, PROT_NONE));
CHECK_EQ(0, mprotect(protected_page_, page_size_, PROT_NONE));
}

~DataEndingAtUnreadablePage() {
const size_t page_size = sysconf(_SC_PAGESIZE);
// Undo the mprotect.
CHECK_EQ(0, mprotect(protected_page_, page_size, PROT_READ|PROT_WRITE));
CHECK_EQ(0, mprotect(protected_page_, page_size_, PROT_READ|PROT_WRITE));
CHECK_EQ(0, munmap(mem_, alloc_size_));
}

Expand All @@ -110,6 +110,7 @@ class DataEndingAtUnreadablePage {
char* protected_page_;
const char* data_;
size_t size_;
size_t page_size_;
};

#else // HAVE_FUNC_MMAP && HAVE_FUNC_SYSCONF
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15 changes: 8 additions & 7 deletions snappy_unittest.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -61,11 +61,12 @@ namespace {
class DataEndingAtUnreadablePage {
public:
explicit DataEndingAtUnreadablePage(const std::string& s) {
const size_t page_size = sysconf(_SC_PAGESIZE);
long page_size = sysconf(_SC_PAGESIZE);
page_size_ = (size_t)(page_size < 0 ? 4096 : page_size);
const size_t size = s.size();
// Round up space for string to a multiple of page_size.
size_t space_for_string = (size + page_size - 1) & ~(page_size - 1);
alloc_size_ = space_for_string + page_size;
// Round up space for string to a multiple of page_size_.
size_t space_for_string = (size + page_size_ - 1) & ~(page_size_ - 1);
alloc_size_ = space_for_string + page_size_;
mem_ = mmap(NULL, alloc_size_,
PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
CHECK_NE(MAP_FAILED, mem_);
Expand All @@ -75,13 +76,12 @@ class DataEndingAtUnreadablePage {
data_ = dst;
size_ = size;
// Make guard page unreadable.
CHECK_EQ(0, mprotect(protected_page_, page_size, PROT_NONE));
CHECK_EQ(0, mprotect(protected_page_, page_size_, PROT_NONE));
}

~DataEndingAtUnreadablePage() {
const size_t page_size = sysconf(_SC_PAGESIZE);
// Undo the mprotect.
CHECK_EQ(0, mprotect(protected_page_, page_size, PROT_READ|PROT_WRITE));
CHECK_EQ(0, mprotect(protected_page_, page_size_, PROT_READ|PROT_WRITE));
CHECK_EQ(0, munmap(mem_, alloc_size_));
}

Expand All @@ -94,6 +94,7 @@ class DataEndingAtUnreadablePage {
char* protected_page_;
const char* data_;
size_t size_;
size_t page_size_;
};

#else // HAVE_FUNC_MMAP) && HAVE_FUNC_SYSCONF
Expand Down