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fix(media-loader): improve safety in the event protocol interface install fails

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This commit is contained in:
Alex Zenla
2025-10-27 23:56:12 -04:00
parent 0b6523906d
commit 268a2cb28b
1 changed files with 40 additions and 11 deletions
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51
src/utils/media_loader.rs
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@@ -160,7 +160,7 @@ impl MediaLoaderHandle {
// Install a protocol interface for the device path.
// This ensures it can be located by other EFI programs.
let mut handle = unsafe {
let primary_handle = unsafe {
uefi::boot::install_protocol_interface(
None,
&DevicePathProtocol::GUID,
@@ -183,25 +183,54 @@ impl MediaLoaderHandle {
let protocol = Box::leak(protocol);
// Install a protocol interface for the load file protocol for the media loader protocol.
handle = unsafe {
let secondary_handle = unsafe {
uefi::boot::install_protocol_interface(
Some(handle),
Some(primary_handle),
&LoadFile2Protocol::GUID,
protocol as *mut _ as *mut c_void,
// The UEFI API expects an opaque pointer here.
protocol as *mut MediaLoaderProtocol as *mut c_void,
)
}
.context("unable to install media loader load file handle")?;
};
// Check if the media loader is registered.
// If it is not, we can't continue safely because something went wrong.
if !Self::already_registered(guid)? {
bail!("media loader not registered when expected to be registered");
// If installing the second protocol interface failed, we need to clean up after ourselves.
if secondary_handle.is_err() {
// Uninstall the protocol interface for the device path protocol.
// SAFETY: If we have reached this point, we know that the protocol is registered.
// If this fails, we have no choice but to leak memory. The error will be shown
// to the user, so at least they can see it. In most cases, catching this error
// will exit, so leaking is safe.
unsafe {
uefi::boot::uninstall_protocol_interface(
primary_handle,
&DevicePathProtocol::GUID,
path.as_ffi_ptr() as *mut c_void,
)
.context(
"unable to uninstall media loader device path handle, this will leak memory",
)?;
}
// SAFETY: We know that the protocol is leaked, so we can safely take a reference to it.
let protocol = unsafe { Box::from_raw(protocol) };
// SAFETY: We know that the data is leaked, so we can safely take a reference to it.
let data = unsafe { Box::from_raw(data) };
// SAFETY: We know that the path is leaked, so we can safely take a reference to it.
let path = unsafe { Box::from_raw(path) };
// Drop all the allocations explicitly to clarify the lifetime.
drop(protocol);
drop(data);
drop(path);
}
// If installing the second protocol interface failed, this will return the error.
// We should have already cleaned up after ourselves, so this is safe.
secondary_handle.context("unable to install media loader load file handle")?;
// Return a handle to the media loader.
Ok(Self {
guid,
handle,
handle: primary_handle,
protocol,
path,
})