Re: [RFC v5 0/8] Stack trace support in X64 exception handling

["Yao, Jiewen" <jiewen.yao@intel.com>]

Hi Paulo
I have some more thought on #3 for your consideration.

Given the situation that we are doing heap guard feature, a *valid* EIP address might not be enough to guarantee the address is inside of an *executable* page.

I am thinking if we need check the non-executable bit (BIT63) as well for DumpImageModuleNames(). (No need for DumpStacktrace()).
We can add IsLogicalAddressExecutable() on top of IsLogicalAddressValid().


Also I do not object the idea to add check inside of PeCoffSearchImageBase().
I am thinking in another way - we can let *caller* to input a validation function for the PeCoffLib, instead of let PeCoffLib depend on another library.

For example:
PeCoffSearchImageBaseEx (Address, ValidateAddressFunc)

Thank you
Yao Jiewen


> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Yao,
> Jiewen
> Sent: Wednesday, January 17, 2018 8:57 PM
> To: Paulo Alcantara <paulo@paulo.ac>; edk2-devel@lists.01.org
> Cc: Rick Bramley <richard.bramley@hp.com>; Dong, Eric
> <eric.dong@intel.com>; Kimon Berlin <kimon.berlin@hp.com>; Andrew Fish
> <afish@apple.com>; Diego Medaglia <diego.meaglia@hp.com>; Laszlo Ersek
> <lersek@redhat.com>
> Subject: Re: [edk2] [RFC v5 0/8] Stack trace support in X64 exception handling
> 
> Thanks Paulo.
> 
> The series looks really good. I give it thumb up. :-)
> 
> The 8 patches keep updating 4 files, so I squash them when I review. The
> comment below is for the final code, not for a specific patch.
> 
> 1) CpuExceptionCommon.c: IsLinearAddressRangeValid().
>   //
>   // Check for valid input parameters
>   //
>   if (LinearAddressStart == 0 || LinearAddressEnd == 0 ||
>       LinearAddressStart > LinearAddressEnd) {
>     return FALSE;
>   }
> 
> I think LinearAddressStart is a valid case. In BIOS, we do update IVT in 0 address
> when CSM is enabled.
> I do not think we need exclude it here. If we enabled ZeroPointer protection, it
> can be excluded in page table parsing.
> 
> 2) I found below logic appears in 2 functions - DumpImageModuleNames() and
> DumpStacktrace(). Is that possible to merge them?
> We can calculate in DumpImageAndCpuContent() and use Eip as parameter. Just
> in case there is 3rd function need use EIP, it won't miss the calculation.
> (It is a bug fix we did recently.)
> 
>   //
>   // Set current EIP address
>   //
>   if ((ExceptionType == EXCEPT_IA32_PAGE_FAULT) &&
>       ((SystemContext.SystemContextIa32->ExceptionData &
> IA32_PF_EC_ID) != 0)) {
>     //
>     // The EIP in SystemContext could not be used
>     // if it is page fault with I/D set.
>     //
>     Eip = *(UINT32 *)(UINTN)SystemContext.SystemContextIa32->Esp;
>   } else {
>     Eip = SystemContext.SystemContextIa32->Eip;
>   }
> 
> 3) I am a little surprised on PeCoffSearchImageBase() issue.
> 
> We have 4 PeCoffSearchImageBase() call in each arch.
> DumpImageModuleNames() calls twice and DumpStacktrace() calls twice.
> Do you know which specific one triggers the zero address #PF issue?
> 
> 
> C:\home\EdkIIGit\edk2\UefiCpuPkg\Library\CpuExceptionHandlerLib\Ia32\Arch
> ExceptionHandler.c(547):  ImageBase = PeCoffSearchImageBase (Eip);
> 
> C:\home\EdkIIGit\edk2\UefiCpuPkg\Library\CpuExceptionHandlerLib\Ia32\Arch
> ExceptionHandler.c(613):    ImageBase = PeCoffSearchImageBase (Eip);
> 
> C:\home\EdkIIGit\edk2\UefiCpuPkg\Library\CpuExceptionHandlerLib\Ia32\Arch
> ExceptionHandler.c(682):  ImageBase = PeCoffSearchImageBase (Eip);
> 
> C:\home\EdkIIGit\edk2\UefiCpuPkg\Library\CpuExceptionHandlerLib\Ia32\Arch
> ExceptionHandler.c(741):    ImageBase = PeCoffSearchImageBase (Eip);
> 
> C:\home\EdkIIGit\edk2\UefiCpuPkg\Library\CpuExceptionHandlerLib\X64\Arch
> ExceptionHandler.c(540):  ImageBase = PeCoffSearchImageBase (Rip);
> 
> C:\home\EdkIIGit\edk2\UefiCpuPkg\Library\CpuExceptionHandlerLib\X64\Arch
> ExceptionHandler.c(613):    ImageBase = PeCoffSearchImageBase (Rip);
> 
> C:\home\EdkIIGit\edk2\UefiCpuPkg\Library\CpuExceptionHandlerLib\X64\Arch
> ExceptionHandler.c(710):  ImageBase = PeCoffSearchImageBase (Rip);
> 
> C:\home\EdkIIGit\edk2\UefiCpuPkg\Library\CpuExceptionHandlerLib\X64\Arch
> ExceptionHandler.c(779):    ImageBase = PeCoffSearchImageBase (Rip);
> 
> The EIP from SystemContext seems good. I assume there is not a problem here.
> 
>   if ((ExceptionType == EXCEPT_IA32_PAGE_FAULT) &&
>       ((SystemContext.SystemContextIa32->ExceptionData &
> IA32_PF_EC_ID) != 0)) {
>     //
>     // The EIP in SystemContext could not be used
>     // if it is page fault with I/D set.
>     //
>     Eip = *(UINT32 *)(UINTN)SystemContext.SystemContextIa32->Esp;
>   } else {
>     Eip = SystemContext.SystemContextIa32->Eip;
>   }
> 
>   //
>   // Get initial PE/COFF image base address from current EIP
>   //
>   ImageBase = PeCoffSearchImageBase (Eip);
> 
> But the EIP from stack frame is unknown and risky. Especially for the code in
> mode-switch, such as PEI->DXE, UEFI->CSM, AP wakeup->AP C code, SMM
> entrypoint->SMM C code.
> Should we add a check for EIP here?
> 
>     //
>     // Set EIP with return address from current stack frame
>     //
>     Eip = *(UINT32 *)((UINTN)Ebp + 4);
> 
>     //
>     // If EIP is zero, then stop unwinding the stack
>     //
>     if (Eip == 0) {
>       break;
>     }
> 
>     //
>     // Search for the respective PE/COFF image based on EIP
>     //
>     ImageBase = PeCoffSearchImageBase (Eip);
> 
> If you can help us do some more investigation on the root-cause and narrow
> down the issue, I will appreciate that.
> 
> We can decide how to fix once it is root-caused.
> 
> Maybe we just do a simple IsLogicalAddressValid () check before we call
> PeCoffSearchImageBase(). :-)
> 
> 
> Thank you
> Yao Jiewen
> 
> > -----Original Message-----
> > From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
> Paulo
> > Alcantara
> > Sent: Monday, January 15, 2018 8:23 AM
> > To: edk2-devel@lists.01.org
> > Cc: Rick Bramley <richard.bramley@hp.com>; Dong, Eric
> > <eric.dong@intel.com>; Kimon Berlin <kimon.berlin@hp.com>; Andrew Fish
> > <afish@apple.com>; Yao, Jiewen <jiewen.yao@intel.com>; Diego Medaglia
> > <diego.meaglia@hp.com>; Laszlo Ersek <lersek@redhat.com>
> > Subject: [edk2] [RFC v5 0/8] Stack trace support in X64 exception handling
> >
> > Hi,
> >
> > This series adds stack trace support during IA32 and X64 CPU exceptions.
> >
> > Informations like back trace, stack contents and image module names
> > (that were part of the call stack) will be dumped out.
> >
> > The current limitation is that it relies on available frame pointers
> > (GCC only) in order to successfully unwind the stack.
> >
> > Jiewen,
> >
> > Thank you very much for your time on this. I've applied the changes you
> > suggested, as well as tested it on IA32 PAE paging mode - it worked as
> > expected.
> >
> > Other than that, I also tested the stack trace in SMM code by manually
> > calling CpuBreakPoint() and then it broke with another exception
> > (page fault). I didn't have much time to look into that, but what I've
> > observed is that the page fault ocurred during the search of PE/COFF
> > image base address (in PeCoffSearchImageBase). The function attempts to
> > search for the image base from "Address" through 0, so any of those
> > dereferenced addresses triggers the page fault.
> >
> > Do you know how we could fix that issue? Perhaps introducing a
> > AddressValidationLib (as Brian suggested previously) and use it within
> > PeCoffSearchImageBase()?
> >
> > I'd also like to thank Brian & Jeff for all the support!
> >
> > Thanks
> > Paulo
> >
> > Repo:   https://github.com/pcacjr/edk2.git
> > Branch: stacktrace_v5
> >
> > Cc: Rick Bramley <richard.bramley@hp.com>
> > Cc: Kimon Berlin <kimon.berlin@hp.com>
> > Cc: Diego Medaglia <diego.meaglia@hp.com>
> > Cc: Andrew Fish <afish@apple.com>
> > Cc: Eric Dong <eric.dong@intel.com>
> > Cc: Laszlo Ersek <lersek@redhat.com>
> > Cc: Brian Johnson <brian.johnson@hpe.com>
> > Cc: Jeff Fan <vanjeff_919@hotmail.com>
> > Cc: Jiewen Yao <jiewen.yao@intel.com>
> > Cc: Paulo Alcantara <paulo@hp.com>
> > Contributed-under: TianoCore Contribution Agreement 1.1
> > Signed-off-by: Paulo Alcantara <paulo@paulo.ac>
> > ---
> >
> > v1 -> v2:
> >   * Add IA32 arch support (GCC toolchain only)
> >   * Replace hard-coded stack alignment value (16) with
> >     CPU_STACK_ALIGNMENT.
> >   * Check for proper stack and frame pointer alignments.
> >   * Fix initialization of UnwoundStacksCount to 1.
> >   * Move GetPdbFileName() to common code since it will be used by both
> >     IA32 and X64 implementations.
> >
> > v2 -> v3:
> >   * Fixed wrong assumption about "RIP < ImageBase" to start searching
> >     for another PE/COFF image. That is, RIP may point to lower and
> >     higher addresses for any other PE/COFF images. Both IA32 & X64.
> >     (Thanks Andrew & Jiewen)
> >   * Fixed typo: unwond -> unwound. Both IA32 & X64. (Thanks Brian)
> >
> > v3 -> v4:
> >   * Validate all frame/stack pointer addresses before dereferencing them
> >     as requested by Brian & Jiewen.
> >   * Correctly print out IP addresses during the stack traces (by Jeff)
> >
> > v4 -> v5:
> >   * Fixed address calculations and improved code as suggested by Jiewen.
> >   * Fixed parameter validation as suggested by Brian.
> >   * Tested stack stack with IA32 PAE paging mode.
> >
> > Paulo Alcantara (8):
> >   UefiCpuPkg/CpuExceptionHandlerLib/X64: Add stack trace support
> >   UefiCpuPkg/CpuExceptionHandlerLib: Export GetPdbFileName()
> >   UefiCpuPkg/CpuExceptionHandlerLib/Ia32: Add stack trace support
> >   UefiCpuPkg/CpuExceptionHandlerLib: Add helper to validate memory
> >     addresses
> >   UefiCpuPkg/CpuExceptionHandlerLib: Ensure valid frame/stack pointers
> >   UefiCpuPkg/CpuExceptionHandlerLib: Correctly print IP addresses
> >   UefiCpuPkg/CpuExceptionHandlerLib: Validate memory address ranges
> >   UefiCpuPkg/CpuExceptionHandlerLib: Add early check in
> >     DumpStackContents
> >
> >  UefiCpuPkg/Library/CpuExceptionHandlerLib/CpuExceptionCommon.c
> > | 537 ++++++++++++++++++--
> >  UefiCpuPkg/Library/CpuExceptionHandlerLib/CpuExceptionCommon.h
> > |  59 ++-
> >  UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c |
> > 483 +++++++++++++++++-
> >  UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c
> |
> > 426 +++++++++++++++-
> >  4 files changed, 1435 insertions(+), 70 deletions(-)
> >
> > --
> > 2.14.3
> >
> > _______________________________________________
> > edk2-devel mailing list
> > edk2-devel@lists.01.org
> > https://lists.01.org/mailman/listinfo/edk2-devel
> _______________________________________________
> edk2-devel mailing list
> edk2-devel@lists.01.org
> https://lists.01.org/mailman/listinfo/edk2-devel