Push@ cf574f0a1838665498e43e9c029d8c1211cbbfa3 Regards, Jian
> -----Original Message----- > From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of Wang, > Jian J > Sent: Tuesday, May 14, 2019 11:14 AM > To: devel@edk2.groups.io; ler...@redhat.com > Cc: Zeng, Star <star.z...@intel.com>; Dong, Eric <eric.d...@intel.com>; Ni, > Ray <ray...@intel.com> > Subject: Re: [edk2-devel] [PATCH] UefiCpuPkg PiSmmCpuDxeSmm: Only support > IN/OUT IO save state read (CVE-2018-12182) > > Laszlo, > > > -----Original Message----- > > From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of > > Laszlo Ersek > > Sent: Tuesday, May 14, 2019 12:46 AM > > To: devel@edk2.groups.io; Wang, Jian J <jian.j.w...@intel.com> > > Cc: Zeng, Star <star.z...@intel.com>; Dong, Eric <eric.d...@intel.com>; Ni, > > Ray <ray...@intel.com> > > Subject: Re: [edk2-devel] [PATCH] UefiCpuPkg PiSmmCpuDxeSmm: Only > support > > IN/OUT IO save state read (CVE-2018-12182) > > > > On 05/10/19 07:16, Wang, Jian J wrote: > > > From: Star Zeng <star.z...@intel.com> > > > > > > BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=1136 > > > CVE: CVE-2018-12182 > > > > > > Customer met system hang-up during serial port loopback test in OS. > > > It is a corner case happened with one CPU core doing "out dx,al" and > > > another CPU core(s) doing "rep outs dx,byte ptr [rsi]". > > > > > > Detailed code flow is as below. > > > > > > 1. Serial port loopback test in OS. > > > One CPU core: "out dx,al" -> Writing B2h, SMI will happen. > > > Another CPU core(s): "rep outs dx,byte ptr [rsi]". > > > > > > 2. SMI happens to enter SMM. > > > "out dx" (SMM_IO_TYPE_OUT_DX) is saved as I/O instruction type in > > > SMRAM save state for CPU doing "out dx,al". > > > "rep outs dx" (SMM_IO_TYPE_REP_OUTS) is saved as I/O instruction > > > type and rsi is save as I/O Memory Address in SMRAM save state for > > > CPU doing "rep outs dx, byte ptr [rsi]". > > > > > > NOTE: I/O Memory Address (rsi) is a virtual address mapped by > > > OS/Virtual Machine. > > > > > > 3. Some SMM code calls EFI_SMM_CPU_PROTOCOL.ReadSaveState() with > > > EFI_SMM_SAVE_STATE_REGISTER_IO and parse data returned. > > > > > > For example: > > > https://github.com/tianocore/edk2/blob/master/QuarkSocPkg/ > > > > > > QuarkNorthCluster/Smm/DxeSmm/QncSmmDispatcher/QNC/QNCSmmSw.c#L7 > > 6 > > > > > > 4. SmmReadSaveState() is executed to read save state for > > > EFI_SMM_SAVE_STATE_REGISTER_IO. > > > > > > - The SmmReadSaveState() function in > > > "UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c" calls the > > > SmmCpuFeaturesReadSaveStateRegister() function, from the platform's > > > SmmCpuFeaturesLib instance. > > > > > > - If that platform-specific function returns EFI_UNSUPPORTED, then > > > PiSmmCpuDxeSmm falls back to the common function > > > ReadSaveStateRegister(), defined in file > > > "UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c". > > > > > > Current ReadSaveStateRegister() in > > > UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c is trying to copy data > > > from I/O Memory Address for EFI_SMM_SAVE_STATE_IO_TYPE_REP_PREFIX, > > > PF will happen as SMM page table does not know and cover this > > > OS/Virtual Machine virtual address. > > > > > > Same case is for SmmCpuFeaturesReadSaveStateRegister() in platform- > > > specific SmmCpuFeaturesLib instance if it has similar implementation > > > to read save state for EFI_SMM_SAVE_STATE_REGISTER_IO with > > > EFI_SMM_SAVE_STATE_IO_TYPE_REP_PREFIX. > > > > > > Same case is for "ins", 'outs' and 'rep ins'. > > > > > > So to fix the problem, this patch updates the code to only support > > > IN/OUT, but not INS/OUTS/REP INS/REP OUTS for SmmReadSaveState(). > > > > > > Cc: Eric Dong <eric.d...@intel.com> > > > Cc: Ray Ni <ray...@intel.com> > > > Cc: Laszlo Ersek <ler...@redhat.com> > > > Signed-off-by: Star Zeng <star.z...@intel.com> > > > --- > > > UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c | 17 +++++++++-------- > > > 1 file changed, 9 insertions(+), 8 deletions(-) > > > > > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c > > b/UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c > > > index 26e365eabc..08cb9c05cf 100644 > > > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c > > > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c > > > @@ -360,7 +360,6 @@ ReadSaveStateRegister ( > > > UINT32 SmmRevId; > > > SMRAM_SAVE_STATE_IOMISC IoMisc; > > > EFI_SMM_SAVE_STATE_IO_INFO *IoInfo; > > > - VOID *IoMemAddr; > > > > > > // > > > // Check for special EFI_SMM_SAVE_STATE_REGISTER_LMA > > > @@ -406,6 +405,14 @@ ReadSaveStateRegister ( > > > return EFI_NOT_FOUND; > > > } > > > > > > + // > > > + // Only support IN/OUT, but not INS/OUTS/REP INS/REP OUTS. > > > + // > > > + if ((mSmmCpuIoType[IoMisc.Bits.Type] != > > EFI_SMM_SAVE_STATE_IO_TYPE_INPUT) && > > > + (mSmmCpuIoType[IoMisc.Bits.Type] != > > EFI_SMM_SAVE_STATE_IO_TYPE_OUTPUT)) { > > > + return EFI_UNSUPPORTED; > > > > I think this return value (EFI_UNSUPPORTED) should be replaced with > > EFI_NOT_FOUND, here. > > > > The return value from this function will be propagated to the caller, > > through SmmReadSaveState() > > [UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c]. > > > > The latter function implements EFI_MM_CPU_PROTOCOL.ReadSaveState(), > and > > the PI-1.7 spec writes, > > > > If the CPU does not support the specified register Register, then > > EFI_NOT_FOUND should be returned. If the CPU does not support the > > specified register width Width , then EFI_INVALID_PARAMETER is > > returned. > > > > I don't feel too strongly about this, but I think it's worth > > considering. If others think EFI_UNSUPPORTED is better, I'm OK with > > that, in the end. > > > > Either way, > > > > Reviewed-by: Laszlo Ersek <ler...@redhat.com> > > > > I agree. EFI_NOT_FOUND is better than EFI_UNSUPPORTED. At least returning > EFI_UNSUPPORTED will somewhat break spec. Thanks for catching this. > > Regards, > Jian > > > Thanks > > Laszlo > > > > > > > > > + } > > > + > > > // > > > // Compute index for the I/O Length and I/O Type lookup tables > > > // > > > @@ -425,13 +432,7 @@ ReadSaveStateRegister ( > > > IoInfo->IoPort = (UINT16)IoMisc.Bits.Port; > > > IoInfo->IoWidth = mSmmCpuIoWidth[IoMisc.Bits.Length].IoWidth; > > > IoInfo->IoType = mSmmCpuIoType[IoMisc.Bits.Type]; > > > - if (IoInfo->IoType == EFI_SMM_SAVE_STATE_IO_TYPE_INPUT || IoInfo- > > >IoType == EFI_SMM_SAVE_STATE_IO_TYPE_OUTPUT) { > > > - ReadSaveStateRegister (CpuIndex, > EFI_SMM_SAVE_STATE_REGISTER_RAX, > > mSmmCpuIoWidth[IoMisc.Bits.Length].Width, &IoInfo->IoData); > > > - } > > > - else { > > > - ReadSaveStateRegisterByIndex(CpuIndex, > > SMM_SAVE_STATE_REGISTER_IOMEMADDR_INDEX, sizeof(IoMemAddr), > > &IoMemAddr); > > > - CopyMem(&IoInfo->IoData, IoMemAddr, > > mSmmCpuIoWidth[IoMisc.Bits.Length].Width); > > > - } > > > + ReadSaveStateRegister (CpuIndex, > EFI_SMM_SAVE_STATE_REGISTER_RAX, > > mSmmCpuIoWidth[IoMisc.Bits.Length].Width, &IoInfo->IoData); > > > return EFI_SUCCESS; > > > } > > > > > > > > > > > > > > > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#40588): https://edk2.groups.io/g/devel/message/40588 Mute This Topic: https://groups.io/mt/31573867/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
