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LibGfx: Don't allow creating bitmaps whose sizes would overflow

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If the area or size_in_bytes calculation for a Gfx::Bitmap would
overflow, we now refuse to create such a bitmap and return nullptr.

Thanks to @itamar8910 for finding this! :^)
This commit is contained in:
Andreas Kling 2020-04-15 11:57:24 +02:00
parent a8406aa117
commit 228ace854c
5 changed files with 62 additions and 21 deletions
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46
Libraries/LibGfx/Bitmap.cpp
View file

@ -38,13 +38,30 @@
namespace Gfx {
NonnullRefPtr<Bitmap> Bitmap::create(BitmapFormat format, const Size& size)
static bool size_would_overflow(BitmapFormat format, const Size& size)
{
if (size.width() < 0 || size.height() < 0)
return true;
size_t bpp = Bitmap::bpp_for_format(format);
size_t result = 0;
if (__builtin_mul_overflow((size_t)size.width(), (size_t)size.height(), &result))
return true;
if (__builtin_mul_overflow(result, bpp, &result))
return true;
return false;
}
RefPtr<Bitmap> Bitmap::create(BitmapFormat format, const Size& size)
{
if (size_would_overflow(format, size))
return nullptr;
return adopt(*new Bitmap(format, size, Purgeable::No));
}
NonnullRefPtr<Bitmap> Bitmap::create_purgeable(BitmapFormat format, const Size& size)
RefPtr<Bitmap> Bitmap::create_purgeable(BitmapFormat format, const Size& size)
{
if (size_would_overflow(format, size))
return nullptr;
return adopt(*new Bitmap(format, size, Purgeable::Yes));
}
@ -55,6 +72,7 @@ Bitmap::Bitmap(BitmapFormat format, const Size& size, Purgeable purgeable)
, m_purgeable(purgeable == Purgeable::Yes)
{
ASSERT(!m_size.is_empty());
ASSERT(!size_would_overflow(format, size));
if (format == BitmapFormat::Indexed8)
m_palette = new RGBA32[256];
int map_flags = purgeable == Purgeable::Yes ? (MAP_PURGEABLE | MAP_PRIVATE) : (MAP_ANONYMOUS | MAP_PRIVATE);
@ -63,8 +81,10 @@ Bitmap::Bitmap(BitmapFormat format, const Size& size, Purgeable purgeable)
m_needs_munmap = true;
}
NonnullRefPtr<Bitmap> Bitmap::create_wrapper(BitmapFormat format, const Size& size, size_t pitch, RGBA32* data)
RefPtr<Bitmap> Bitmap::create_wrapper(BitmapFormat format, const Size& size, size_t pitch, RGBA32* data)
{
if (size_would_overflow(format, size))
return nullptr;
return adopt(*new Bitmap(format, size, pitch, data));
}
@ -79,12 +99,15 @@ Bitmap::Bitmap(BitmapFormat format, const Size& size, size_t pitch, RGBA32* data
, m_pitch(pitch)
, m_format(format)
{
ASSERT(!size_would_overflow(format, size));
if (format == BitmapFormat::Indexed8)
m_palette = new RGBA32[256];
}
NonnullRefPtr<Bitmap> Bitmap::create_with_shared_buffer(BitmapFormat format, NonnullRefPtr<SharedBuffer>&& shared_buffer, const Size& size)
RefPtr<Bitmap> Bitmap::create_with_shared_buffer(BitmapFormat format, NonnullRefPtr<SharedBuffer>&& shared_buffer, const Size& size)
{
if (size_would_overflow(format, size))
return nullptr;
return adopt(*new Bitmap(format, move(shared_buffer), size));
}
@ -96,14 +119,17 @@ Bitmap::Bitmap(BitmapFormat format, NonnullRefPtr<SharedBuffer>&& shared_buffer,
, m_shared_buffer(move(shared_buffer))
{
ASSERT(format != BitmapFormat::Indexed8);
ASSERT(!size_would_overflow(format, size));
}
NonnullRefPtr<Gfx::Bitmap> Bitmap::rotated(Gfx::RotationDirection rotation_direction) const
RefPtr<Gfx::Bitmap> Bitmap::rotated(Gfx::RotationDirection rotation_direction) const
{
auto w = this->width();
auto h = this->height();
auto new_bitmap = Gfx::Bitmap::create(this->format(), { h, w });
if (!new_bitmap)
return nullptr;
for (int i = 0; i < w; i++) {
for (int j = 0; j < h; j++) {
@ -120,12 +146,14 @@ NonnullRefPtr<Gfx::Bitmap> Bitmap::rotated(Gfx::RotationDirection rotation_direc
return new_bitmap;
}
NonnullRefPtr<Gfx::Bitmap> Bitmap::flipped(Gfx::Orientation orientation) const
RefPtr<Gfx::Bitmap> Bitmap::flipped(Gfx::Orientation orientation) const
{
auto w = this->width();
auto h = this->height();
auto new_bitmap = Gfx::Bitmap::create(this->format(), { w, h });
if (!new_bitmap)
return nullptr;
for (int i = 0; i < w; i++) {
for (int j = 0; j < h; j++) {
@ -140,12 +168,14 @@ NonnullRefPtr<Gfx::Bitmap> Bitmap::flipped(Gfx::Orientation orientation) const
return new_bitmap;
}
NonnullRefPtr<Bitmap> Bitmap::to_bitmap_backed_by_shared_buffer() const
RefPtr<Bitmap> Bitmap::to_bitmap_backed_by_shared_buffer() const
{
if (m_shared_buffer)
return *this;
auto buffer = SharedBuffer::create_with_size(size_in_bytes());
auto bitmap = Bitmap::create_with_shared_buffer(m_format, *buffer, m_size);
if (!bitmap)
return nullptr;
memcpy(buffer->data(), scanline(0), size_in_bytes());
return bitmap;
}
@ -210,6 +240,8 @@ int Bitmap::shbuf_id() const
ShareableBitmap Bitmap::to_shareable_bitmap(pid_t peer_pid) const
{
auto bitmap = to_bitmap_backed_by_shared_buffer();
if (!bitmap)
return {};
if (peer_pid > 0)
bitmap->shared_buffer()->share_with(peer_pid);
return ShareableBitmap(*bitmap);

23
Libraries/LibGfx/Bitmap.h
View file

@ -49,15 +49,15 @@ enum RotationDirection {
class Bitmap : public RefCounted<Bitmap> {
public:
static NonnullRefPtr<Bitmap> create(BitmapFormat, const Size&);
static NonnullRefPtr<Bitmap> create_purgeable(BitmapFormat, const Size&);
static NonnullRefPtr<Bitmap> create_wrapper(BitmapFormat, const Size&, size_t pitch, RGBA32*);
static RefPtr<Bitmap> create(BitmapFormat, const Size&);
static RefPtr<Bitmap> create_purgeable(BitmapFormat, const Size&);
static RefPtr<Bitmap> create_wrapper(BitmapFormat, const Size&, size_t pitch, RGBA32*);
static RefPtr<Bitmap> load_from_file(const StringView& path);
static NonnullRefPtr<Bitmap> create_with_shared_buffer(BitmapFormat, NonnullRefPtr<SharedBuffer>&&, const Size&);
static RefPtr<Bitmap> create_with_shared_buffer(BitmapFormat, NonnullRefPtr<SharedBuffer>&&, const Size&);
NonnullRefPtr<Gfx::Bitmap> rotated(Gfx::RotationDirection) const;
NonnullRefPtr<Gfx::Bitmap> flipped(Gfx::Orientation) const;
NonnullRefPtr<Bitmap> to_bitmap_backed_by_shared_buffer() const;
RefPtr<Gfx::Bitmap> rotated(Gfx::RotationDirection) const;
RefPtr<Gfx::Bitmap> flipped(Gfx::Orientation) const;
RefPtr<Bitmap> to_bitmap_backed_by_shared_buffer() const;
ShareableBitmap to_shareable_bitmap(pid_t peer_pid = -1) const;
@ -79,9 +79,9 @@ public:
SharedBuffer* shared_buffer() { return m_shared_buffer.ptr(); }
const SharedBuffer* shared_buffer() const { return m_shared_buffer.ptr(); }
unsigned bpp() const
static unsigned bpp_for_format(BitmapFormat format)
{
switch (m_format) {
switch (format) {
case BitmapFormat::Indexed8:
return 8;
case BitmapFormat::RGB32:
@ -94,6 +94,11 @@ public:
}
}
unsigned bpp() const
{
return bpp_for_format(m_format);
}
void fill(Color);
bool has_alpha_channel() const { return m_format == BitmapFormat::RGBA32; }