Reviewers: Vyacheslav Egorov, Chris Evans,
Description:
Add guard pages in front of platform allocations
BUG=1555
Please review this at http://codereview.chromium.org/7352007/
SVN Base: http://v8.googlecode.com/svn/trunk/
Affected files:
M src/platform-linux.cc
M src/platform-macos.cc
M src/platform-win32.cc
Index: src/platform-linux.cc
===================================================================
--- src/platform-linux.cc (revision 8619)
+++ src/platform-linux.cc (working copy)
@@ -370,13 +370,16 @@
// TODO(805): Port randomization of allocated executable memory to Linux.
const size_t msize = RoundUp(requested, sysconf(_SC_PAGESIZE));
int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
- void* mbase = mmap(NULL, msize, prot, MAP_PRIVATE | MAP_ANONYMOUS, -1,
0);
+ void* mbase = mmap(NULL, msize + Page::kPageSize, prot,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (mbase == MAP_FAILED) {
LOG(i::Isolate::Current(),
StringEvent("OS::Allocate", "mmap failed"));
return NULL;
}
*allocated = msize;
+ mprotect(mbase, Page::kPageSize, PROT_NONE);
+ mbase += Page::kPageSize;
UpdateAllocatedSpaceLimits(mbase, msize);
return mbase;
}
@@ -384,7 +387,7 @@
void OS::Free(void* address, const size_t size) {
// TODO(1240712): munmap has a return value which is ignored here.
- int result = munmap(address, size);
+ int result = munmap(address - Page::kPageSize, size + Page::kPageSize);
USE(result);
ASSERT(result == 0);
}
Index: src/platform-macos.cc
===================================================================
--- src/platform-macos.cc (revision 8619)
+++ src/platform-macos.cc (working copy)
@@ -148,7 +148,7 @@
bool is_executable) {
const size_t msize = RoundUp(requested, getpagesize());
int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
- void* mbase = mmap(NULL, msize, prot,
+ void* mbase = mmap(NULL, msize + Page::kPageSize, prot,
MAP_PRIVATE | MAP_ANON,
kMmapFd, kMmapFdOffset);
if (mbase == MAP_FAILED) {
@@ -156,6 +156,8 @@
return NULL;
}
*allocated = msize;
+ mprotect(mbase, Page::kPageSize, PROT_NONE);
+ mbase += Page::kPageSize;
UpdateAllocatedSpaceLimits(mbase, msize);
return mbase;
}
@@ -163,7 +165,7 @@
void OS::Free(void* address, const size_t size) {
// TODO(1240712): munmap has a return value which is ignored here.
- int result = munmap(address, size);
+ int result = munmap(address - Page::kPageSize, size + Page::kPageSize);
USE(result);
ASSERT(result == 0);
}
Index: src/platform-win32.cc
===================================================================
--- src/platform-win32.cc (revision 8619)
+++ src/platform-win32.cc (working copy)
@@ -913,11 +913,14 @@
}
LPVOID mbase = VirtualAlloc(reinterpret_cast<void *>(address),
- msize,
+ msize + Page::kPageSize,
MEM_COMMIT | MEM_RESERVE,
prot);
if (mbase == NULL && address != 0)
- mbase = VirtualAlloc(NULL, msize, MEM_COMMIT | MEM_RESERVE, prot);
+ mbase = VirtualAlloc(NULL,
+ msize + Page::kPageSize,
+ MEM_COMMIT | MEM_RESERVE,
+ prot);
if (mbase == NULL) {
LOG(ISOLATE, StringEvent("OS::Allocate", "VirtualAlloc failed"));
@@ -925,8 +928,12 @@
}
ASSERT(IsAligned(reinterpret_cast<size_t>(mbase),
OS::AllocateAlignment()));
+ *allocated = msize;
- *allocated = msize;
+ DWORD old_protect;
+ VirtualProtect(mbase, Page::kPageSize, PAGE_READONLY | PAGE_GUARD,
&old_protect);
+ mbase = static_cast<BYTE*>(mbase) + Page::kPageSize;
+
UpdateAllocatedSpaceLimits(mbase, static_cast<int>(msize));
return mbase;
}
@@ -934,7 +941,7 @@
void OS::Free(void* address, const size_t size) {
// TODO(1240712): VirtualFree has a return value which is ignored here.
- VirtualFree(address, 0, MEM_RELEASE);
+ VirtualFree(static_cast<BYTE*>(address) - Page::kPageSize, 0,
MEM_RELEASE);
USE(size);
}
--
v8-dev mailing list
[email protected]
http://groups.google.com/group/v8-dev
