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Kernel: Allow writes larger than PAGE_SIZE to AC97 device

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Previously, `cat /dev/random > /dev/audio` would crash Serenity. Fix
this by splitting up the written data into `PAGE_SIZE` chunks.
This commit is contained in:
Jelle Raaijmakers 2021-11-23 12:49:37 +01:00 committed by Andreas Kling
parent 70ca8b24dc
commit eb2b0d847e
Notes: sideshowbarker 2024-07-18 00:48:32 +09:00 
Author: https://github.com/gmta
Commit: https://github.com/SerenityOS/serenity/commit/eb2b0d847ea
Pull-request: https://github.com/SerenityOS/serenity/pull/11039
2 changed files with 18 additions and 6 deletions
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23
Kernel/Devices/Audio/AC97.cpp
View file

@ -169,8 +169,6 @@ void AC97::set_pcm_output_volume(u8 left_channel, u8 right_channel, Muted mute)
ErrorOr<size_t> AC97::write(OpenFileDescription&, u64, UserOrKernelBuffer const& data, size_t length)
{
VERIFY(length <= PAGE_SIZE);
if (!m_output_buffer) {
m_output_buffer = TRY(allocate_physical_buffer(m_output_buffer_page_count * PAGE_SIZE, "AC97 Output buffer"sv));
}
@ -179,9 +177,23 @@ ErrorOr<size_t> AC97::write(OpenFileDescription&, u64, UserOrKernelBuffer const&
m_buffer_descriptor_list = TRY(allocate_physical_buffer(buffer_descriptor_list_size, "AC97 Buffer Descriptor List"sv));
}
cli();
auto remaining = length;
size_t offset = 0;
while (remaining > 0) {
TRY(write_single_buffer(data, offset, min(remaining, PAGE_SIZE)));
offset += PAGE_SIZE;
remaining -= PAGE_SIZE;
}
return length;
}
ErrorOr<void> AC97::write_single_buffer(UserOrKernelBuffer const& data, size_t offset, size_t length)
{
VERIFY(length <= PAGE_SIZE);
// Block until we can write into an unused buffer
cli();
do {
auto pcm_out_status = m_pcm_out_channel.reg(AC97Channel::Register::Status).in<u16>();
auto is_dma_controller_halted = (pcm_out_status & AudioStatusRegisterFlag::DMAControllerHalted) > 0;
@ -199,11 +211,10 @@ ErrorOr<size_t> AC97::write(OpenFileDescription&, u64, UserOrKernelBuffer const&
m_irq_queue.wait_forever("AC97"sv);
} while (m_pcm_out_channel.dma_running());
sti();
// Copy data from userspace into one of our buffers
TRY(data.read(m_output_buffer->vaddr_from_page_index(m_output_buffer_page_index).as_ptr(), length));
TRY(data.read(m_output_buffer->vaddr_from_page_index(m_output_buffer_page_index).as_ptr(), offset, length));
if (!m_pcm_out_channel.dma_running()) {
reset_pcm_out();
@ -226,7 +237,7 @@ ErrorOr<size_t> AC97::write(OpenFileDescription&, u64, UserOrKernelBuffer const&
m_output_buffer_page_index = (m_output_buffer_page_index + 1) % m_output_buffer_page_count;
m_buffer_descriptor_list_index = (m_buffer_descriptor_list_index + 1) % buffer_descriptor_list_max_entries;
return length;
return {};
}
void AC97::AC97Channel::reset()

1
Kernel/Devices/Audio/AC97.h
View file

@ -152,6 +152,7 @@ private:
void set_master_output_volume(u8, u8, Muted);
void set_pcm_output_sample_rate(u16);
void set_pcm_output_volume(u8, u8, Muted);
ErrorOr<void> write_single_buffer(UserOrKernelBuffer const&, size_t, size_t);
OwnPtr<Memory::Region> m_buffer_descriptor_list;
u8 m_buffer_descriptor_list_index = 0;