Kernel: Add a VERIFY() to make sure our DMA address is valid

This checks whether the address we're trying to use for DMA is low enough so as not to overflow the I/O register.
Author: https://github.com/gunnarbeutner Commit: 9b14a8605a Pull-request: https://github.com/SerenityOS/serenity/pull/8109 Issue: https://github.com/SerenityOS/serenity/issues/8092
2025-07-30 20:59:16 +00:00 · 2021-06-17 19:29:49 +02:00 · 2021-06-17 19:29:49 +02:00 · 9b14a8605a · 2024-07-18 12:07:09 +09:00
commit 9b14a8605a
parent 017c5fc7d9
1 changed files with 3 additions and 0 deletions
--- a/Kernel/Devices/SB16.cpp
+++ b/Kernel/Devices/SB16.cpp
@ -200,6 +200,9 @@ void SB16::dma_start(uint32_t length)

    // Write the buffer
    IO::out8(0x8b, addr >> 16);
+    auto page_number = addr >> 16;
+    VERIFY(page_number <= NumericLimits<u8>::max());
+    IO::out8(0x8b, page_number);

    // Enable the DMA channel
    IO::out8(0xd4, (channel % 4));