Re: [edk2-devel] [PATCH v4 7/7] OvmfPkg/LinuxInitrdDynamicShellCommand: bail if initrd already exists

["Ard Biesheuvel" <ard.biesheuvel@linaro.org>]

On Tue, 3 Mar 2020 at 22:08, Laszlo Ersek <lersek@redhat.com> wrote:
>
> On 03/03/20 22:03, Laszlo Ersek wrote:
> > On 03/03/20 15:01, Ard Biesheuvel wrote:
> >> Before taking any actions, check if an instance of the LoadFile2 exists
> >> already on the Linux initrd media GUID device path, and whether it was
> >> provided by this command. If so, abort, since no duplicate instances of
> >> the device path should exist.
> >>
> >> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2564
> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> >> ---
> >>  OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c   | 31 ++++++++++++++++++++
> >>  OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni |  3 ++
> >>  2 files changed, 34 insertions(+)
> >>
> >> diff --git a/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c
> >> index 47ed26b50d3a..ed8fbaa77069 100644
> >> --- a/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c
> >> +++ b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c
> >> @@ -53,6 +53,33 @@ STATIC CONST SINGLE_NODE_VENDOR_MEDIA_DEVPATH mInitrdDevicePath = {
> >>    }
> >>  };
> >>
> >> +STATIC
> >> +BOOLEAN
> >> +IsOtherInitrdDevicePathAlreadyInstalled (
> >> +  VOID
> >> +  )
> >> +{
> >> +  EFI_STATUS                  Status;
> >> +  EFI_DEVICE_PATH_PROTOCOL    *DevicePath;
> >> +  EFI_HANDLE                  Handle;
> >> +
> >> +  DevicePath = (EFI_DEVICE_PATH_PROTOCOL *)&mInitrdDevicePath;
> >> +  Status = gBS->LocateDevicePath (&gEfiLoadFile2ProtocolGuid, &DevicePath,
> >> +                  &Handle);
> >> +  if (EFI_ERROR (Status)) {
> >> +    return FALSE;
> >> +  }
> >> +
> >> +  //
> >> +  // Check whether the existing instance is one that we installed during
> >> +  // a previous invocation.
> >> +  //
> >> +  if (Handle == mInitrdLoadFile2Handle) {
> >> +    return FALSE;
> >> +  }
> >> +  return TRUE;
> >> +}
> >
> > Looks good, the function will return TRUE when mInitrdLoadFile2Handle is
> > NULL.
>
> To clarify, what I mean is that the controlling expression
>
>   (Handle == mInitrdLoadFile2Handle)
>
> assuming it is reached, will evaluate to 0, if mInitrdLoadFile2Handle is
> NULL. That's because Handle cannot be NULL at that point. Hence the
> function will return TRUE.
>

Indeed

> > Reviewed-by: Laszlo Ersek <lersek@redhat.com>
> >

Thanks!

I will push this series (asl well as the TPM one for ArmVirtPkg)
tomorrow, once the stable tag is assigned.


> >
> >
> >> +
> >>  STATIC
> >>  EFI_STATUS
> >>  EFIAPI
> >> @@ -217,6 +244,10 @@ RunInitrd (
> >>      } else {
> >>        ASSERT(FALSE);
> >>      }
> >> +  } else if (IsOtherInitrdDevicePathAlreadyInstalled ()) {
> >> +    ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_ALREADY_INSTALLED),
> >> +      mLinuxInitrdShellCommandHiiHandle, L"initrd");
> >> +    ShellStatus = SHELL_UNSUPPORTED;
> >>    } else {
> >>      if (ShellCommandLineGetCount (Package) > 2) {
> >>        ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_TOO_MANY),
> >> diff --git a/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni
> >> index a88fa6e3641b..4b6b1285fffd 100644
> >> --- a/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni
> >> +++ b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni
> >> @@ -18,6 +18,7 @@
> >>  #langdef   en-US "english"
> >>
> >>  #string STR_GEN_PROBLEM           #language en-US "%H%s%N: Unknown flag - '%H%s%N'\r\n"
> >> +#string STR_GEN_ALREADY_INSTALLED #language en-US "%H%s%N: Linux initrd already provided by platform\r\n"
> >>  #string STR_GEN_TOO_MANY          #language en-US "%H%s%N: Too many arguments.\r\n"
> >>  #string STR_GEN_TOO_FEW           #language en-US "%H%s%N: Too few arguments.\r\n"
> >>  #string STR_GEN_FIND_FAIL         #language en-US "%H%s%N: File not found - '%H%s%N'\r\n"
> >> @@ -47,3 +48,5 @@
> >>  "     Consumers of the LoadFile2 protocol on the LINUX_EFI_INITRD_MEDIA_GUID\r\n"
> >>  "     device path that are started via means other than the shell will be able\r\n"
> >>  "     to locate the protocol and invoke it.\r\n"
> >> +"  3. Exposing an initrd using this command is only supported if no initrd is\r\n"
> >> +"     already being exposed by another driver on the platform.\r\n"
> >>
> >
>
>
> 
>