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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v7] Avoid crash calling PrintErrMesg from efi_multiboot2
On Fri, Mar 21, 2025 at 10:32:58AM +0000, Frediano Ziglio wrote:
> Although code is compiled with -fpic option data is not position
> independent. This causes data pointer to become invalid if
> code is not relocated properly which is what happens for
> efi_multiboot2 which is called by multiboot entry code.
>
> Code tested adding
> PrintErrMesg(L"Test message", EFI_BUFFER_TOO_SMALL);
> in efi_multiboot2 before calling efi_arch_edd (this function
> can potentially call PrintErrMesg).
>
> Before the patch (XenServer installation on Qemu, xen replaced
> with vanilla xen.gz):
> Booting `XenServer (Serial)'Booting `XenServer (Serial)'
> Test message: !!!! X64 Exception Type - 0E(#PF - Page-Fault) CPU Apic ID -
> 00000000 !!!!
> ExceptionData - 0000000000000000 I:0 R:0 U:0 W:0 P:0 PK:0 SS:0 SGX:0
> RIP - 000000007EE21E9A, CS - 0000000000000038, RFLAGS - 0000000000210246
> RAX - 000000007FF0C1B5, RCX - 0000000000000050, RDX - 0000000000000010
> RBX - 0000000000000000, RSP - 000000007FF0C180, RBP - 000000007FF0C210
> RSI - FFFF82D040467CE8, RDI - 0000000000000000
> R8 - 000000007FF0C1C8, R9 - 000000007FF0C1C0, R10 - 0000000000000000
> R11 - 0000000000001020, R12 - FFFF82D040467CE8, R13 - 000000007FF0C1B8
> R14 - 000000007EA33328, R15 - 000000007EA332D8
> DS - 0000000000000030, ES - 0000000000000030, FS - 0000000000000030
> GS - 0000000000000030, SS - 0000000000000030
> CR0 - 0000000080010033, CR2 - FFFF82D040467CE8, CR3 - 000000007FC01000
> CR4 - 0000000000000668, CR8 - 0000000000000000
> DR0 - 0000000000000000, DR1 - 0000000000000000, DR2 - 0000000000000000
> DR3 - 0000000000000000, DR6 - 00000000FFFF0FF0, DR7 - 0000000000000400
> GDTR - 000000007F9DB000 0000000000000047, LDTR - 0000000000000000
> IDTR - 000000007F48E018 0000000000000FFF, TR - 0000000000000000
> FXSAVE_STATE - 000000007FF0BDE0
> !!!! Find image based on IP(0x7EE21E9A) (No PDB)
> (ImageBase=000000007EE20000, EntryPoint=000000007EE23935) !!!!
>
> After the patch:
> Booting `XenServer (Serial)'Booting `XenServer (Serial)'
> Test message: Buffer too small
> BdsDxe: loading Boot0000 "UiApp" from
> Fv(7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1)/FvFile(462CAA21-7614-4503-836E-8AB6F4662331)
> BdsDxe: starting Boot0000 "UiApp" from
> Fv(7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1)/FvFile(462CAA21-7614-4503-836E-8AB6F4662331)
>
> This partially rollback commit 00d5d5ce23e6.
>
> Fixes: 9180f5365524 ("x86: add multiboot2 protocol support for EFI platforms")
> Signed-off-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxx>
-no-jump-tables is available since clang 3.9.0 (and since GCC 4.1.0), so
with upgraded base toolchain requirements it's safe to commit this now.
Acked-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
> ---
> Changes since v1:
> - added "Fixes:" tag;
> - fixed cast style change.
>
> Changes since v2:
> - wrap long line.
>
> Changes since v3:
> - fixed "Fixes:" tag.
>
> Changes since v4:
> - use switch instead of tables.
>
> Changes since v5:
> - added -fno-jump-tables option.
>
> Changes since v6:
> - rebased.
> ---
> xen/common/efi/boot.c | 58 ++++++++++++++++++++++++------------
> xen/common/efi/efi-common.mk | 1 +
> 2 files changed, 40 insertions(+), 19 deletions(-)
>
> diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
> index efbec00af9..143b5681ba 100644
> --- a/xen/common/efi/boot.c
> +++ b/xen/common/efi/boot.c
> @@ -287,33 +287,53 @@ static bool __init match_guid(const EFI_GUID *guid1,
> const EFI_GUID *guid2)
> /* generic routine for printing error messages */
> static void __init PrintErrMesg(const CHAR16 *mesg, EFI_STATUS ErrCode)
> {
> - static const CHAR16* const ErrCodeToStr[] __initconstrel = {
> - [~EFI_ERROR_MASK & EFI_NOT_FOUND] = L"Not found",
> - [~EFI_ERROR_MASK & EFI_NO_MEDIA] = L"The device has no
> media",
> - [~EFI_ERROR_MASK & EFI_MEDIA_CHANGED] = L"Media changed",
> - [~EFI_ERROR_MASK & EFI_DEVICE_ERROR] = L"Device error",
> - [~EFI_ERROR_MASK & EFI_VOLUME_CORRUPTED] = L"Volume corrupted",
> - [~EFI_ERROR_MASK & EFI_ACCESS_DENIED] = L"Access denied",
> - [~EFI_ERROR_MASK & EFI_OUT_OF_RESOURCES] = L"Out of resources",
> - [~EFI_ERROR_MASK & EFI_VOLUME_FULL] = L"Volume is full",
> - [~EFI_ERROR_MASK & EFI_SECURITY_VIOLATION] = L"Security violation",
> - [~EFI_ERROR_MASK & EFI_CRC_ERROR] = L"CRC error",
> - [~EFI_ERROR_MASK & EFI_COMPROMISED_DATA] = L"Compromised data",
> - [~EFI_ERROR_MASK & EFI_BUFFER_TOO_SMALL] = L"Buffer too small",
> - };
> - EFI_STATUS ErrIdx = ErrCode & ~EFI_ERROR_MASK;
> -
> StdOut = StdErr;
> PrintErr(mesg);
> PrintErr(L": ");
>
> - if( (ErrIdx < ARRAY_SIZE(ErrCodeToStr)) && ErrCodeToStr[ErrIdx] )
> - mesg = ErrCodeToStr[ErrIdx];
> - else
> + switch (ErrCode)
> {
> + case EFI_NOT_FOUND:
> + mesg = L"Not found";
> + break;
> + case EFI_NO_MEDIA:
> + mesg = L"The device has no media";
> + break;
> + case EFI_MEDIA_CHANGED:
> + mesg = L"Media changed";
> + break;
> + case EFI_DEVICE_ERROR:
> + mesg = L"Device error";
> + break;
> + case EFI_VOLUME_CORRUPTED:
> + mesg = L"Volume corrupted";
> + break;
> + case EFI_ACCESS_DENIED:
> + mesg = L"Access denied";
> + break;
> + case EFI_OUT_OF_RESOURCES:
> + mesg = L"Out of resources";
> + break;
> + case EFI_VOLUME_FULL:
> + mesg = L"Volume is full";
> + break;
> + case EFI_SECURITY_VIOLATION:
> + mesg = L"Security violation";
> + break;
> + case EFI_CRC_ERROR:
> + mesg = L"CRC error";
> + break;
> + case EFI_COMPROMISED_DATA:
> + mesg = L"Compromised data";
> + break;
> + case EFI_BUFFER_TOO_SMALL:
> + mesg = L"Buffer too small";
> + break;
> + default:
> PrintErr(L"ErrCode: ");
> DisplayUint(ErrCode, 0);
> mesg = NULL;
> + break;
> }
> blexit(mesg);
> }
> diff --git a/xen/common/efi/efi-common.mk b/xen/common/efi/efi-common.mk
> index 23cafcf20c..06b1c19674 100644
> --- a/xen/common/efi/efi-common.mk
> +++ b/xen/common/efi/efi-common.mk
> @@ -2,6 +2,7 @@ EFIOBJ-y := boot.init.o pe.init.o ebmalloc.o runtime.o
> EFIOBJ-$(CONFIG_COMPAT) += compat.o
>
> CFLAGS-y += -fshort-wchar
> +CFLAGS-y += -fno-jump-tables
> CFLAGS-y += -iquote $(srctree)/common/efi
> CFLAGS-y += -iquote $(srcdir)
>
> --
> 2.43.0
>
--
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
Attachment:
signature.asc
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