diff mbox series

[v4] Avoid crash calling PrintErrMesg from efi_multiboot2

Message ID 20240819142953.415817-1-frediano.ziglio@cloud.com (mailing list archive)
State New
Headers show
Series [v4] Avoid crash calling PrintErrMesg from efi_multiboot2 | expand

Commit Message

Frediano Ziglio Aug. 19, 2024, 2:29 p.m. UTC 
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  - 000000007DC29E46, CS  - 0000000000000038, RFLAGS - 0000000000210246
  RAX  - 0000000000000000, RCX - 0000000000000050, RDX - 0000000000000000
  RBX  - 000000007DAB4558, RSP - 000000007EFA1200, RBP - 0000000000000000
  RSI  - FFFF82D040467A88, RDI - 0000000000000000
  R8   - 000000007EFA1238, R9  - 000000007EFA1230, R10 - 0000000000000000
  R11  - 000000007CF42665, R12 - FFFF82D040467A88, R13 - 000000007EFA1228
  R14  - 000000007EFA1225, R15 - 000000007DAB45A8
  DS   - 0000000000000030, ES  - 0000000000000030, FS  - 0000000000000030
  GS   - 0000000000000030, SS  - 0000000000000030
  CR0  - 0000000080010033, CR2 - FFFF82D040467A88, CR3 - 000000007EC01000
  CR4  - 0000000000000668, CR8 - 0000000000000000
  DR0  - 0000000000000000, DR1 - 0000000000000000, DR2 - 0000000000000000
  DR3  - 0000000000000000, DR6 - 00000000FFFF0FF0, DR7 - 0000000000000400
  GDTR - 000000007E9E2000 0000000000000047, LDTR - 0000000000000000
  IDTR - 000000007E4E5018 0000000000000FFF,   TR - 0000000000000000
  FXSAVE_STATE - 000000007EFA0E60
  !!!! Find image based on IP(0x7DC29E46) (No PDB)  (ImageBase=000000007DC28000, EntryPoint=000000007DC2B917) !!!!

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)

Fixes: 9180f5365524 ("x86: add multiboot2 protocol support for EFI platforms")
Signed-off-by: Frediano Ziglio <frediano.ziglio@cloud.com>
---
 xen/common/efi/boot.c | 46 ++++++++++++++++++++++++++++++-------------
 1 file changed, 32 insertions(+), 14 deletions(-)
---
Changes since v1:
- added "Fixes:" tag;
- fixed cast style change.

Changes since v2:
- wrap long line.

Changes since v3:
- fixed "Fixes:" tag.

Comments

Frediano Ziglio Aug. 29, 2024, 9:03 a.m. UTC | #1 
On Mon, Aug 19, 2024 at 3:30 PM Frediano Ziglio
<frediano.ziglio@cloud.com> 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  - 000000007DC29E46, CS  - 0000000000000038, RFLAGS - 0000000000210246
>   RAX  - 0000000000000000, RCX - 0000000000000050, RDX - 0000000000000000
>   RBX  - 000000007DAB4558, RSP - 000000007EFA1200, RBP - 0000000000000000
>   RSI  - FFFF82D040467A88, RDI - 0000000000000000
>   R8   - 000000007EFA1238, R9  - 000000007EFA1230, R10 - 0000000000000000
>   R11  - 000000007CF42665, R12 - FFFF82D040467A88, R13 - 000000007EFA1228
>   R14  - 000000007EFA1225, R15 - 000000007DAB45A8
>   DS   - 0000000000000030, ES  - 0000000000000030, FS  - 0000000000000030
>   GS   - 0000000000000030, SS  - 0000000000000030
>   CR0  - 0000000080010033, CR2 - FFFF82D040467A88, CR3 - 000000007EC01000
>   CR4  - 0000000000000668, CR8 - 0000000000000000
>   DR0  - 0000000000000000, DR1 - 0000000000000000, DR2 - 0000000000000000
>   DR3  - 0000000000000000, DR6 - 00000000FFFF0FF0, DR7 - 0000000000000400
>   GDTR - 000000007E9E2000 0000000000000047, LDTR - 0000000000000000
>   IDTR - 000000007E4E5018 0000000000000FFF,   TR - 0000000000000000
>   FXSAVE_STATE - 000000007EFA0E60
>   !!!! Find image based on IP(0x7DC29E46) (No PDB)  (ImageBase=000000007DC28000, EntryPoint=000000007DC2B917) !!!!
>
> 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)
>
> Fixes: 9180f5365524 ("x86: add multiboot2 protocol support for EFI platforms")
> Signed-off-by: Frediano Ziglio <frediano.ziglio@cloud.com>
> ---
>  xen/common/efi/boot.c | 46 ++++++++++++++++++++++++++++++-------------
>  1 file changed, 32 insertions(+), 14 deletions(-)
> ---
> Changes since v1:
> - added "Fixes:" tag;
> - fixed cast style change.
>
> Changes since v2:
> - wrap long line.
>
> Changes since v3:
> - fixed "Fixes:" tag.
>
> diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
> index efbec00af9..fdbe75005c 100644
> --- a/xen/common/efi/boot.c
> +++ b/xen/common/efi/boot.c
> @@ -287,19 +287,36 @@ 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",
> +#define ERROR_MESSAGE_LIST \
> +    ERROR_MESSAGE(EFI_NOT_FOUND, "Not found") \
> +    ERROR_MESSAGE(EFI_NO_MEDIA, "The device has no media") \
> +    ERROR_MESSAGE(EFI_MEDIA_CHANGED, "Media changed") \
> +    ERROR_MESSAGE(EFI_DEVICE_ERROR, "Device error") \
> +    ERROR_MESSAGE(EFI_VOLUME_CORRUPTED, "Volume corrupted") \
> +    ERROR_MESSAGE(EFI_ACCESS_DENIED, "Access denied") \
> +    ERROR_MESSAGE(EFI_OUT_OF_RESOURCES, "Out of resources") \
> +    ERROR_MESSAGE(EFI_VOLUME_FULL, "Volume is full") \
> +    ERROR_MESSAGE(EFI_SECURITY_VIOLATION, "Security violation") \
> +    ERROR_MESSAGE(EFI_CRC_ERROR, "CRC error") \
> +    ERROR_MESSAGE(EFI_COMPROMISED_DATA, "Compromised data") \
> +    ERROR_MESSAGE(EFI_BUFFER_TOO_SMALL, "Buffer too small")
> +
> +    static const struct ErrorStrings {
> +        CHAR16 start;
> +#undef ERROR_MESSAGE
> +#define ERROR_MESSAGE(code, str) CHAR16 msg_ ## code[sizeof(str)];
> +        ERROR_MESSAGE_LIST
> +    } ErrorStrings __initconst = {
> +        0
> +#undef ERROR_MESSAGE
> +#define ERROR_MESSAGE(code, str) , L ## str
> +        ERROR_MESSAGE_LIST
> +    };
> +    static const uint16_t ErrCodeToStr[] __initconst = {
> +#undef ERROR_MESSAGE
> +#define ERROR_MESSAGE(code, str) \
> +        [~EFI_ERROR_MASK & code] = offsetof(struct ErrorStrings, msg_ ## code),
> +        ERROR_MESSAGE_LIST
>      };
>      EFI_STATUS ErrIdx = ErrCode & ~EFI_ERROR_MASK;
>
> @@ -308,7 +325,8 @@ static void __init PrintErrMesg(const CHAR16 *mesg, EFI_STATUS ErrCode)
>      PrintErr(L": ");
>
>      if( (ErrIdx < ARRAY_SIZE(ErrCodeToStr)) && ErrCodeToStr[ErrIdx] )
> -        mesg = ErrCodeToStr[ErrIdx];
> +        mesg = (const CHAR16 *)((const void *)&ErrorStrings +
> +                                ErrCodeToStr[ErrIdx]);
>      else
>      {
>          PrintErr(L"ErrCode: ");

Any update on this?

Frediano
Frediano Ziglio Sept. 11, 2024, 9:13 a.m. UTC | #2 
On Thu, Aug 29, 2024 at 10:03 AM Frediano Ziglio <frediano.ziglio@cloud.com>
wrote:

> On Mon, Aug 19, 2024 at 3:30 PM Frediano Ziglio
> <frediano.ziglio@cloud.com> 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  - 000000007DC29E46, CS  - 0000000000000038, RFLAGS -
> 0000000000210246
> >   RAX  - 0000000000000000, RCX - 0000000000000050, RDX - 0000000000000000
> >   RBX  - 000000007DAB4558, RSP - 000000007EFA1200, RBP - 0000000000000000
> >   RSI  - FFFF82D040467A88, RDI - 0000000000000000
> >   R8   - 000000007EFA1238, R9  - 000000007EFA1230, R10 - 0000000000000000
> >   R11  - 000000007CF42665, R12 - FFFF82D040467A88, R13 - 000000007EFA1228
> >   R14  - 000000007EFA1225, R15 - 000000007DAB45A8
> >   DS   - 0000000000000030, ES  - 0000000000000030, FS  - 0000000000000030
> >   GS   - 0000000000000030, SS  - 0000000000000030
> >   CR0  - 0000000080010033, CR2 - FFFF82D040467A88, CR3 - 000000007EC01000
> >   CR4  - 0000000000000668, CR8 - 0000000000000000
> >   DR0  - 0000000000000000, DR1 - 0000000000000000, DR2 - 0000000000000000
> >   DR3  - 0000000000000000, DR6 - 00000000FFFF0FF0, DR7 - 0000000000000400
> >   GDTR - 000000007E9E2000 0000000000000047, LDTR - 0000000000000000
> >   IDTR - 000000007E4E5018 0000000000000FFF,   TR - 0000000000000000
> >   FXSAVE_STATE - 000000007EFA0E60
> >   !!!! Find image based on IP(0x7DC29E46) (No PDB)
> (ImageBase=000000007DC28000, EntryPoint=000000007DC2B917) !!!!
> >
> > 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)
> >
> > Fixes: 9180f5365524 ("x86: add multiboot2 protocol support for EFI
> platforms")
> > Signed-off-by: Frediano Ziglio <frediano.ziglio@cloud.com>
> > ---
> >  xen/common/efi/boot.c | 46 ++++++++++++++++++++++++++++++-------------
> >  1 file changed, 32 insertions(+), 14 deletions(-)
> > ---
> > Changes since v1:
> > - added "Fixes:" tag;
> > - fixed cast style change.
> >
> > Changes since v2:
> > - wrap long line.
> >
> > Changes since v3:
> > - fixed "Fixes:" tag.
> >
> > diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
> > index efbec00af9..fdbe75005c 100644
> > --- a/xen/common/efi/boot.c
> > +++ b/xen/common/efi/boot.c
> > @@ -287,19 +287,36 @@ 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",
> > +#define ERROR_MESSAGE_LIST \
> > +    ERROR_MESSAGE(EFI_NOT_FOUND, "Not found") \
> > +    ERROR_MESSAGE(EFI_NO_MEDIA, "The device has no media") \
> > +    ERROR_MESSAGE(EFI_MEDIA_CHANGED, "Media changed") \
> > +    ERROR_MESSAGE(EFI_DEVICE_ERROR, "Device error") \
> > +    ERROR_MESSAGE(EFI_VOLUME_CORRUPTED, "Volume corrupted") \
> > +    ERROR_MESSAGE(EFI_ACCESS_DENIED, "Access denied") \
> > +    ERROR_MESSAGE(EFI_OUT_OF_RESOURCES, "Out of resources") \
> > +    ERROR_MESSAGE(EFI_VOLUME_FULL, "Volume is full") \
> > +    ERROR_MESSAGE(EFI_SECURITY_VIOLATION, "Security violation") \
> > +    ERROR_MESSAGE(EFI_CRC_ERROR, "CRC error") \
> > +    ERROR_MESSAGE(EFI_COMPROMISED_DATA, "Compromised data") \
> > +    ERROR_MESSAGE(EFI_BUFFER_TOO_SMALL, "Buffer too small")
> > +
> > +    static const struct ErrorStrings {
> > +        CHAR16 start;
> > +#undef ERROR_MESSAGE
> > +#define ERROR_MESSAGE(code, str) CHAR16 msg_ ## code[sizeof(str)];
> > +        ERROR_MESSAGE_LIST
> > +    } ErrorStrings __initconst = {
> > +        0
> > +#undef ERROR_MESSAGE
> > +#define ERROR_MESSAGE(code, str) , L ## str
> > +        ERROR_MESSAGE_LIST
> > +    };
> > +    static const uint16_t ErrCodeToStr[] __initconst = {
> > +#undef ERROR_MESSAGE
> > +#define ERROR_MESSAGE(code, str) \
> > +        [~EFI_ERROR_MASK & code] = offsetof(struct ErrorStrings, msg_
> ## code),
> > +        ERROR_MESSAGE_LIST
> >      };
> >      EFI_STATUS ErrIdx = ErrCode & ~EFI_ERROR_MASK;
> >
> > @@ -308,7 +325,8 @@ static void __init PrintErrMesg(const CHAR16 *mesg,
> EFI_STATUS ErrCode)
> >      PrintErr(L": ");
> >
> >      if( (ErrIdx < ARRAY_SIZE(ErrCodeToStr)) && ErrCodeToStr[ErrIdx] )
> > -        mesg = ErrCodeToStr[ErrIdx];
> > +        mesg = (const CHAR16 *)((const void *)&ErrorStrings +
> > +                                ErrCodeToStr[ErrIdx]);
> >      else
> >      {
> >          PrintErr(L"ErrCode: ");
>
> Any update on this?
>
>
ping

The issue still apply, checked that I addressed all comments.

Frediano
diff mbox series

Patch

diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index efbec00af9..fdbe75005c 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -287,19 +287,36 @@  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",
+#define ERROR_MESSAGE_LIST \
+    ERROR_MESSAGE(EFI_NOT_FOUND, "Not found") \
+    ERROR_MESSAGE(EFI_NO_MEDIA, "The device has no media") \
+    ERROR_MESSAGE(EFI_MEDIA_CHANGED, "Media changed") \
+    ERROR_MESSAGE(EFI_DEVICE_ERROR, "Device error") \
+    ERROR_MESSAGE(EFI_VOLUME_CORRUPTED, "Volume corrupted") \
+    ERROR_MESSAGE(EFI_ACCESS_DENIED, "Access denied") \
+    ERROR_MESSAGE(EFI_OUT_OF_RESOURCES, "Out of resources") \
+    ERROR_MESSAGE(EFI_VOLUME_FULL, "Volume is full") \
+    ERROR_MESSAGE(EFI_SECURITY_VIOLATION, "Security violation") \
+    ERROR_MESSAGE(EFI_CRC_ERROR, "CRC error") \
+    ERROR_MESSAGE(EFI_COMPROMISED_DATA, "Compromised data") \
+    ERROR_MESSAGE(EFI_BUFFER_TOO_SMALL, "Buffer too small")
+
+    static const struct ErrorStrings {
+        CHAR16 start;
+#undef ERROR_MESSAGE
+#define ERROR_MESSAGE(code, str) CHAR16 msg_ ## code[sizeof(str)];
+        ERROR_MESSAGE_LIST
+    } ErrorStrings __initconst = {
+        0
+#undef ERROR_MESSAGE
+#define ERROR_MESSAGE(code, str) , L ## str
+        ERROR_MESSAGE_LIST
+    };
+    static const uint16_t ErrCodeToStr[] __initconst = {
+#undef ERROR_MESSAGE
+#define ERROR_MESSAGE(code, str) \
+        [~EFI_ERROR_MASK & code] = offsetof(struct ErrorStrings, msg_ ## code),
+        ERROR_MESSAGE_LIST
     };
     EFI_STATUS ErrIdx = ErrCode & ~EFI_ERROR_MASK;
 
@@ -308,7 +325,8 @@  static void __init PrintErrMesg(const CHAR16 *mesg, EFI_STATUS ErrCode)
     PrintErr(L": ");
 
     if( (ErrIdx < ARRAY_SIZE(ErrCodeToStr)) && ErrCodeToStr[ErrIdx] )
-        mesg = ErrCodeToStr[ErrIdx];
+        mesg = (const CHAR16 *)((const void *)&ErrorStrings +
+                                ErrCodeToStr[ErrIdx]);
     else
     {
         PrintErr(L"ErrCode: ");