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LibGfx/JPEG: Remove the ensure_bounds_okay function

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This function has probably been added when we weren't as good with error
propagations as we are now. We can safely remove it and let future
calls to `read` fail if the file is corrupted.

This can be tested with the following bytes (already used in 9191829a):
ffd8ffc000000800080ef701101200ffda00030100
This commit is contained in:
Lucas CHOLLET 2023-03-29 21:50:22 -04:00 • committed by Tim Flynn
parent 402c9e5e23
commit dc9e783608
1 changed files with 2 additions and 18 deletions
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20
Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.cpp
View file

@ -554,15 +554,6 @@ static ErrorOr<void> decode_huffman_stream(JPEGLoadingContext& context, Vector<M
return {};
}
static inline ErrorOr<void> ensure_bounds_okay(const size_t cursor, const size_t delta, const size_t bound)
{
if (Checked<size_t>::addition_would_overflow(delta, cursor))
return Error::from_string_literal("Bounds are not ok: addition would overflow");
if (delta + cursor >= bound)
return Error::from_string_literal("Bounds are not ok");
return {};
}
static bool is_frame_marker(Marker const marker)
{
// B.1.1.3 - Marker assignments
@ -633,8 +624,7 @@ static ErrorOr<void> read_start_of_scan(AK::SeekableStream& stream, JPEGLoadingC
return Error::from_string_literal("SOS found before reading a SOF");
}
u16 bytes_to_read = TRY(stream.read_value<BigEndian<u16>>()) - 2;
TRY(ensure_bounds_okay(TRY(stream.tell()), bytes_to_read, TRY(stream.size())));
[[maybe_unused]] u16 const bytes_to_read = TRY(stream.read_value<BigEndian<u16>>()) - 2;
u8 const component_count = TRY(stream.read_value<u8>());
Scan current_scan;
@ -711,7 +701,6 @@ static ErrorOr<void> read_restart_interval(AK::SeekableStream& stream, JPEGLoadi
static ErrorOr<void> read_huffman_table(AK::SeekableStream& stream, JPEGLoadingContext& context)
{
i32 bytes_to_read = TRY(stream.read_value<BigEndian<u16>>());
TRY(ensure_bounds_okay(TRY(stream.tell()), bytes_to_read, TRY(stream.size())));
bytes_to_read -= 2;
while (bytes_to_read > 0) {
HuffmanTableSpec table;
@ -865,7 +854,6 @@ static ErrorOr<void> read_colour_encoding(SeekableStream& stream, [[maybe_unused
static ErrorOr<void> read_app_marker(SeekableStream& stream, JPEGLoadingContext& context, int app_marker_number)
{
i32 bytes_to_read = TRY(stream.read_value<BigEndian<u16>>());
TRY(ensure_bounds_okay(TRY(stream.tell()), bytes_to_read, TRY(stream.size())));
if (bytes_to_read <= 2)
return Error::from_string_literal("app marker size too small");
@ -931,10 +919,7 @@ static ErrorOr<void> read_start_of_frame(AK::SeekableStream& stream, JPEGLoading
return Error::from_string_literal("SOF repeated");
}
i32 bytes_to_read = TRY(stream.read_value<BigEndian<u16>>());
bytes_to_read -= 2;
TRY(ensure_bounds_okay(TRY(stream.tell()), bytes_to_read, TRY(stream.size())));
[[maybe_unused]] u16 const bytes_to_read = TRY(stream.read_value<BigEndian<u16>>());
context.frame.precision = TRY(stream.read_value<u8>());
if (context.frame.precision != 8) {
@ -1006,7 +991,6 @@ static ErrorOr<void> read_start_of_frame(AK::SeekableStream& stream, JPEGLoading
static ErrorOr<void> read_quantization_table(AK::SeekableStream& stream, JPEGLoadingContext& context)
{
i32 bytes_to_read = TRY(stream.read_value<BigEndian<u16>>()) - 2;
TRY(ensure_bounds_okay(TRY(stream.tell()), bytes_to_read, TRY(stream.size())));
while (bytes_to_read > 0) {
u8 info_byte = TRY(stream.read_value<u8>());
u8 element_unit_hint = info_byte >> 4;