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Stop allocating RW memory in AllocateGuarded
AllocateGuarded previously fell back on Allocate and then called Guard to set the protection to PROT_NONE. Linux commits RW memory, but the important thing here is to reserve the address space without committing it. This change adds a new variant of Allocate that takes explicit permission bits so that AllocateGuarded allocates non-RW memory from the beginning. Bug: v8:6320 Change-Id: I7962acbed09938951bf3bb4af2d1f302adba2547 Reviewed-on: https://chromium-review.googlesource.com/491928 Commit-Queue: Eric Holk <eholk@chromium.org> Reviewed-by: Mircea Trofin <mtrofin@chromium.org> Reviewed-by: Jochen Eisinger <jochen@chromium.org> Cr-Commit-Position: refs/heads/master@{#45075}
1 parent bf74d43 commit a05743a

13 files changed

Lines changed: 183 additions & 39 deletions

‎src/base/platform/platform-aix.cc‎

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -71,9 +71,10 @@ double AIXTimezoneCache::LocalTimeOffset() {
7171

7272
TimezoneCache* OS::CreateTimezoneCache() { return new AIXTimezoneCache(); }
7373

74-
void* OS::Allocate(const size_t requested, size_t* allocated, bool executable) {
74+
void* OS::Allocate(const size_t requested, size_t* allocated,
75+
OS::MemoryPermission access) {
7576
const size_t msize = RoundUp(requested, getpagesize());
76-
int prot = PROT_READ | PROT_WRITE | (executable ? PROT_EXEC : 0);
77+
int prot = GetProtectionFromMemoryPermission(access);
7778
void* mbase = mmapHelper(msize, prot, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
7879

7980
if (mbase == MAP_FAILED) return NULL;

‎src/base/platform/platform-cygwin.cc‎

Lines changed: 3 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -55,12 +55,10 @@ double CygwinTimezoneCache::LocalTimeOffset() {
5555
(loc->tm_isdst > 0 ? 3600 * msPerSecond : 0));
5656
}
5757

58-
59-
void* OS::Allocate(const size_t requested,
60-
size_t* allocated,
61-
bool is_executable) {
58+
void* OS::Allocate(const size_t requested, size_t* allocated,
59+
OS::MemoryPermission access) {
6260
const size_t msize = RoundUp(requested, sysconf(_SC_PAGESIZE));
63-
int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
61+
int prot = GetProtectionFromMemoryPermission(access);
6462
void* mbase = mmap(NULL, msize, prot, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
6563
if (mbase == MAP_FAILED) return NULL;
6664
*allocated = msize;

‎src/base/platform/platform-freebsd.cc‎

Lines changed: 3 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -37,11 +37,10 @@ namespace base {
3737

3838
TimezoneCache* OS::CreateTimezoneCache() { return new PosixTimezoneCache(); }
3939

40-
void* OS::Allocate(const size_t requested,
41-
size_t* allocated,
42-
bool executable) {
40+
void* OS::Allocate(const size_t requested, size_t* allocated,
41+
OS::MemoryPermission access) {
4342
const size_t msize = RoundUp(requested, getpagesize());
44-
int prot = PROT_READ | PROT_WRITE | (executable ? PROT_EXEC : 0);
43+
int prot = GetProtectionFromMemoryPermission(access);
4544
void* mbase = mmap(NULL, msize, prot, MAP_PRIVATE | MAP_ANON, -1, 0);
4645

4746
if (mbase == MAP_FAILED) return NULL;

‎src/base/platform/platform-linux.cc‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -95,9 +95,9 @@ bool OS::ArmUsingHardFloat() {
9595
TimezoneCache* OS::CreateTimezoneCache() { return new PosixTimezoneCache(); }
9696

9797
void* OS::Allocate(const size_t requested, size_t* allocated,
98-
bool is_executable) {
98+
OS::MemoryPermission access) {
9999
const size_t msize = RoundUp(requested, AllocateAlignment());
100-
int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
100+
int prot = GetProtectionFromMemoryPermission(access);
101101
void* addr = OS::GetRandomMmapAddr();
102102
void* mbase = mmap(addr, msize, prot, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
103103
if (mbase == MAP_FAILED) return NULL;

‎src/base/platform/platform-macos.cc‎

Lines changed: 3 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -51,12 +51,10 @@ namespace base {
5151
static const int kMmapFd = VM_MAKE_TAG(255);
5252
static const off_t kMmapFdOffset = 0;
5353

54-
55-
void* OS::Allocate(const size_t requested,
56-
size_t* allocated,
57-
bool is_executable) {
54+
void* OS::Allocate(const size_t requested, size_t* allocated,
55+
OS::MemoryPermission access) {
5856
const size_t msize = RoundUp(requested, getpagesize());
59-
int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
57+
int prot = GetProtectionFromMemoryPermission(access);
6058
void* mbase = mmap(OS::GetRandomMmapAddr(),
6159
msize,
6260
prot,

‎src/base/platform/platform-openbsd.cc‎

Lines changed: 3 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -35,11 +35,10 @@ namespace base {
3535

3636
TimezoneCache* OS::CreateTimezoneCache() { return new PosixTimezoneCache(); }
3737

38-
void* OS::Allocate(const size_t requested,
39-
size_t* allocated,
40-
bool is_executable) {
38+
void* OS::Allocate(const size_t requested, size_t* allocated,
39+
OS::MemoryPermission access) {
4140
const size_t msize = RoundUp(requested, AllocateAlignment());
42-
int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
41+
int prot = GetProtectionFromMemoryPermission(access);
4342
void* addr = OS::GetRandomMmapAddr();
4443
void* mbase = mmap(addr, msize, prot, MAP_PRIVATE | MAP_ANON, -1, 0);
4544
if (mbase == MAP_FAILED) return NULL;

‎src/base/platform/platform-posix.cc‎

Lines changed: 21 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -101,18 +101,24 @@ intptr_t OS::CommitPageSize() {
101101
return page_size;
102102
}
103103

104+
void* OS::Allocate(const size_t requested, size_t* allocated,
105+
bool is_executable) {
106+
return OS::Allocate(requested, allocated,
107+
is_executable ? OS::MemoryPermission::kReadWriteExecute
108+
: OS::MemoryPermission::kReadWrite);
109+
}
110+
104111
void* OS::AllocateGuarded(const size_t requested) {
105112
size_t allocated = 0;
106-
const bool is_executable = false;
107-
void* mbase = OS::Allocate(requested, &allocated, is_executable);
113+
void* mbase =
114+
OS::Allocate(requested, &allocated, OS::MemoryPermission::kNoAccess);
108115
if (allocated != requested) {
109116
OS::Free(mbase, allocated);
110117
return nullptr;
111118
}
112119
if (mbase == nullptr) {
113120
return nullptr;
114121
}
115-
OS::Guard(mbase, requested);
116122
return mbase;
117123
}
118124

@@ -776,5 +782,17 @@ void Thread::SetThreadLocal(LocalStorageKey key, void* value) {
776782
USE(result);
777783
}
778784

785+
int GetProtectionFromMemoryPermission(OS::MemoryPermission access) {
786+
switch (access) {
787+
case OS::MemoryPermission::kNoAccess:
788+
return PROT_NONE;
789+
case OS::MemoryPermission::kReadWrite:
790+
return PROT_READ | PROT_WRITE;
791+
case OS::MemoryPermission::kReadWriteExecute:
792+
return PROT_READ | PROT_WRITE | PROT_EXEC;
793+
}
794+
UNREACHABLE();
795+
}
796+
779797
} // namespace base
780798
} // namespace v8

‎src/base/platform/platform-posix.h‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -5,6 +5,7 @@
55
#ifndef V8_BASE_PLATFORM_PLATFORM_POSIX_H_
66
#define V8_BASE_PLATFORM_PLATFORM_POSIX_H_
77

8+
#include "src/base/platform/platform.h"
89
#include "src/base/timezone-cache.h"
910

1011
namespace v8 {
@@ -22,6 +23,8 @@ class PosixTimezoneCache : public TimezoneCache {
2223
static const int msPerSecond = 1000;
2324
};
2425

26+
int GetProtectionFromMemoryPermission(OS::MemoryPermission access);
27+
2528
} // namespace base
2629
} // namespace v8
2730

‎src/base/platform/platform-qnx.cc‎

Lines changed: 3 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -86,11 +86,10 @@ bool OS::ArmUsingHardFloat() {
8686

8787
TimezoneCache* OS::CreateTimezoneCache() { return new PosixTimezoneCache(); }
8888

89-
void* OS::Allocate(const size_t requested,
90-
size_t* allocated,
91-
bool is_executable) {
89+
void* OS::Allocate(const size_t requested, size_t* allocated,
90+
OS::MemoryPermission access) {
9291
const size_t msize = RoundUp(requested, AllocateAlignment());
93-
int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
92+
int prot = GetProtectionFromMemoryPermission(access);
9493
void* addr = OS::GetRandomMmapAddr();
9594
void* mbase = mmap(addr, msize, prot, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
9695
if (mbase == MAP_FAILED) return NULL;

‎src/base/platform/platform-solaris.cc‎

Lines changed: 3 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -58,11 +58,10 @@ double SolarisTimezoneCache::LocalTimeOffset() {
5858

5959
TimezoneCache* OS::CreateTimezoneCache() { return new SolarisTimezoneCache(); }
6060

61-
void* OS::Allocate(const size_t requested,
62-
size_t* allocated,
63-
bool is_executable) {
61+
void* OS::Allocate(const size_t requested, size_t* allocated,
62+
OS::MemoryPermission access) {
6463
const size_t msize = RoundUp(requested, getpagesize());
65-
int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
64+
int prot = GetProtectionFromMemoryPermission(access);
6665
void* mbase = mmap(NULL, msize, prot, MAP_PRIVATE | MAP_ANON, -1, 0);
6766

6867
if (mbase == MAP_FAILED) return NULL;

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