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LibGfx: Check bounds of color table accesses in BMPLoader

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Previously, it was possible to crash the decoder by crafting a file
with invalid color table index values.
This commit is contained in:
Tim Ledbetter 2023-10-01 19:45:19 +01:00 committed by Andreas Kling
parent c14db6ab12
commit e6c1429311
Notes: sideshowbarker 2024-07-17 06:33:00 +09:00 
Author: https://github.com/tcl3
Commit: https://github.com/SerenityOS/serenity/commit/e6c1429311
Pull-request: https://github.com/SerenityOS/serenity/pull/21289
Reviewed-by: https://github.com/LucasChollet ✅
1 changed files with 10 additions and 2 deletions
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12
Userland/Libraries/LibGfx/ImageFormats/BMPLoader.cpp
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@ -1292,8 +1292,10 @@ static ErrorOr<void> decode_bmp_pixel_data(BMPLoadingContext& context)
u8 mask = 8;
while (column < width && mask > 0) {
mask -= 1;
auto color_idx = (byte >> mask) & 0x1;
size_t color_idx = (byte >> mask) & 0x1;
if (context.is_included_in_ico) {
if (color_idx >= context.color_table.size())
return Error::from_string_literal("Invalid color table index");
auto color = context.color_table[color_idx];
context.bitmap->scanline(row)[column++] = color;
} else {
@ -1309,8 +1311,10 @@ static ErrorOr<void> decode_bmp_pixel_data(BMPLoadingContext& context)
u8 mask = 8;
while (column < width && mask > 0) {
mask -= 2;
auto color_idx = (byte >> mask) & 0x3;
size_t color_idx = (byte >> mask) & 0x3;
if (context.is_included_in_ico) {
if (color_idx >= context.color_table.size())
return Error::from_string_literal("Invalid color table index");
auto color = context.color_table[color_idx];
context.bitmap->scanline(row)[column++] = color;
} else {
@ -1329,6 +1333,8 @@ static ErrorOr<void> decode_bmp_pixel_data(BMPLoadingContext& context)
u32 low_color_idx = byte & 0xf;
if (context.is_included_in_ico) {
if (high_color_idx >= context.color_table.size() || low_color_idx >= context.color_table.size())
return Error::from_string_literal("Invalid color table index");
auto high_color = context.color_table[high_color_idx];
auto low_color = context.color_table[low_color_idx];
context.bitmap->scanline(row)[column++] = high_color;
@ -1348,6 +1354,8 @@ static ErrorOr<void> decode_bmp_pixel_data(BMPLoadingContext& context)
u8 byte = streamer.read_u8();
if (context.is_included_in_ico) {
if (byte >= context.color_table.size())
return Error::from_string_literal("Invalid color table index");
auto color = context.color_table[byte];
context.bitmap->scanline(row)[column++] = color;
} else {