From 22b0cbe1fe7c5f9dcdf56e4d327a7f3e277d7f81 Mon Sep 17 00:00:00 2001 From: Gunnar Beutner Date: Fri, 18 Jun 2021 13:38:32 +0200 Subject: [PATCH] Kernel: Fix crash when changing screen resolution Steps to reproduce: 1. Change resolution to 640x480. 2. Change resolution to 1280x1024. 3. Observe the following kernel panic: Kernel::__panic(char const*, unsigned int, char const*) +0x55 Kernel::handle_crash(Kernel::RegisterState&, char const*, ...) +0x112 page_fault_handler +0x1130 page_fault_asm_entry +0x26 Kernel::VirtualConsole::refresh_after_resolution_change() +0x35e4 Kernel::ConsoleManagement::resolution_was_changed() +0x38b Kernel::Graphics::FramebufferConsole::set_resolution(...) +0x3e1 Kernel::BochsGraphicsAdapter::try_to_set_resolution(...) +0x319 .L4213 +0x40a Kernel::Process::sys$ioctl(int, unsigned int, unsigned int) +0x2fa Kernel::Syscall::handle(Kernel::RegisterState&, ...) +0xfdc syscall_handler +0x19c0 Kernel::syscall_asm_entry_dummy() +0x31 --- Kernel/TTY/VirtualConsole.cpp | 19 ++++++------------- 1 file changed, 6 insertions(+), 13 deletions(-) diff --git a/Kernel/TTY/VirtualConsole.cpp b/Kernel/TTY/VirtualConsole.cpp index e82a8e854d..318b2f414f 100644 --- a/Kernel/TTY/VirtualConsole.cpp +++ b/Kernel/TTY/VirtualConsole.cpp @@ -151,19 +151,12 @@ void VirtualConsole::refresh_after_resolution_change() } // Note: A potential loss of displayed data occur when resolution width shrinks. - if (columns() < old_columns_count) { - for (size_t row = 0; row < rows(); row++) { - auto& line = m_lines[row]; - memcpy(new_cells->vaddr().offset((row)*columns() * sizeof(Cell)).as_ptr(), m_cells->vaddr().offset((row) * (old_columns_count) * sizeof(Cell)).as_ptr(), columns() * sizeof(Cell)); - line.dirty = true; - } - } else { - // Handle Growth of resolution - for (size_t row = 0; row < rows(); row++) { - auto& line = m_lines[row]; - memcpy(new_cells->vaddr().offset((row)*columns() * sizeof(Cell)).as_ptr(), m_cells->vaddr().offset((row) * (old_columns_count) * sizeof(Cell)).as_ptr(), old_columns_count * sizeof(Cell)); - line.dirty = true; - } + auto common_rows_count = min(old_rows_count, rows()); + auto common_columns_count = min(old_columns_count, columns()); + for (size_t row = 0; row < common_rows_count; row++) { + auto& line = m_lines[row]; + memcpy(new_cells->vaddr().offset(row * columns() * sizeof(Cell)).as_ptr(), m_cells->vaddr().offset(row * old_columns_count * sizeof(Cell)).as_ptr(), common_columns_count * sizeof(Cell)); + line.dirty = true; } // Update the new cells Region