For pointer subtraction, the result is of type "ptrdiff_t". According to
the C11 standard (Committee Draft - April 12, 2011):
"When two pointers are subtracted, both shall point to elements of the
same array object, or one past the last element of the array object; the
result is the difference of the subscripts of the two array elements. The
size of the result is implementation-defined, and its type (a signed
integer type) is ptrdiff_t defined in the <stddef.h> header. If the result
is not representable in an object of that type, the behavior is
undefined."
In our codes, there are cases that the pointer subtraction is not
performed by pointers to elements of the same array object. This might
lead to potential issues, since the behavior is undefined according to C11
standard.
Also, since the size of type "ptrdiff_t" is implementation-defined. Some
static code checkers may warn that the pointer subtraction might underflow
first and then being cast to a bigger size. For example:
UINT8 *Ptr1, *Ptr2;
UINTN PtrDiff;
...
PtrDiff = (UINTN) (Ptr1 - Ptr2);
The commit will refine the pointer subtraction expressions by casting each
pointer to UINTN first and then perform the subtraction:
PtrDiff = (UINTN) Ptr1 - (UINTN) Ptr2;
Cc: Jeff Fan <jeff.fan@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
---
IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c | 4 ++--
IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c | 4 ++--
IntelFrameworkModulePkg/Library/GenericBdsLib/BdsConsole.c | 4 ++--
IntelFrameworkModulePkg/Library/GenericBdsLib/BdsMisc.c | 4 ++--
IntelFrameworkModulePkg/Library/LegacyBootManagerLib/LegacyBm.c | 4 ++--
IntelFrameworkModulePkg/Universal/BdsDxe/BootMaint/BootOption.c | 6 +++---
6 files changed, 13 insertions(+), 13 deletions(-)
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
index 8f91a7d..c4c77ec 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
@@ -1,6 +1,6 @@
/** @file
-Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions
@@ -318,7 +318,7 @@ GetPciLegacyRom (
break;
}
- if ((UINTN)(RomHeader.Raw - (UINT8 *) *Rom) + Pcir->ImageLength * 512 > *ImageSize) {
+ if (((UINTN)RomHeader.Raw - (UINTN)*Rom) + Pcir->ImageLength * 512 > *ImageSize) {
break;
}
diff --git a/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c b/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c
index bba62a8..628424d 100644
--- a/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c
+++ b/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c
@@ -1,7 +1,7 @@
/** @file
BDS Lib functions which relate with create or process the boot option.
-Copyright (c) 2004 - 2016, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2004 - 2017, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
@@ -1034,7 +1034,7 @@ BdsCreateDevOrder (
DevOrderPtr->Length = (UINT16) (sizeof (UINT16) + BEVCount * sizeof (UINT16));
DevOrderPtr = (LEGACY_DEV_ORDER_ENTRY *) BdsFillDevOrderBuf (BbsTable, BBS_BEV_DEVICE, BbsCount, DevOrderPtr->Data);
- ASSERT (TotalSize == (UINTN) ((UINT8 *) DevOrderPtr - (UINT8 *) DevOrder));
+ ASSERT (TotalSize == ((UINTN) DevOrderPtr - (UINTN) DevOrder));
//
// Save device order for legacy boot device to variable.
diff --git a/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsConsole.c b/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsConsole.c
index 1020e84..8f273ff 100644
--- a/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsConsole.c
+++ b/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsConsole.c
@@ -1,7 +1,7 @@
/** @file
BDS Lib functions which contain all the code to connect console device
-Copyright (c) 2004 - 2014, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2004 - 2017, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
@@ -873,7 +873,7 @@ ConvertBmpToGopBlt (
}
- ImageIndex = (UINTN) (Image - ImageHeader);
+ ImageIndex = (UINTN)Image - (UINTN)ImageHeader;
if ((ImageIndex % 4) != 0) {
//
// Bmp Image starts each row on a 32-bit boundary!
diff --git a/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsMisc.c b/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsMisc.c
index 24c1998..2ba511a 100644
--- a/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsMisc.c
+++ b/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsMisc.c
@@ -1,7 +1,7 @@
/** @file
Misc BDS library function
-Copyright (c) 2004 - 2015, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2004 - 2017, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
@@ -669,7 +669,7 @@ BdsLibVariableToOption (
// Get load opion data.
//
LoadOptions = TempPtr;
- LoadOptionsSize = (UINT32) (VariableSize - (UINTN) (TempPtr - Variable));
+ LoadOptionsSize = (UINT32) (VariableSize - ((UINTN)TempPtr - (UINTN)Variable));
//
// The Console variables may have multiple device paths, so make
diff --git a/IntelFrameworkModulePkg/Library/LegacyBootManagerLib/LegacyBm.c b/IntelFrameworkModulePkg/Library/LegacyBootManagerLib/LegacyBm.c
index c56a878..080a436 100644
--- a/IntelFrameworkModulePkg/Library/LegacyBootManagerLib/LegacyBm.c
+++ b/IntelFrameworkModulePkg/Library/LegacyBootManagerLib/LegacyBm.c
@@ -3,7 +3,7 @@
and manage the legacy boot option, all legacy boot option is getting from
the legacy BBS table.
-Copyright (c) 2011 - 2016, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2011 - 2017, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
@@ -725,7 +725,7 @@ LegacyBmCreateDevOrder (
DevOrderPtr->Length = (UINT16) (sizeof (UINT16) + BEVCount * sizeof (UINT16));
DevOrderPtr = (LEGACY_DEV_ORDER_ENTRY *) LegacyBmFillDevOrderBuf (BbsTable, BBS_BEV_DEVICE, BbsCount, DevOrderPtr->Data);
- ASSERT (TotalSize == (UINTN) ((UINT8 *) DevOrderPtr - (UINT8 *) DevOrder));
+ ASSERT (TotalSize == ((UINTN) DevOrderPtr - (UINTN) DevOrder));
//
// Save device order for legacy boot device to variable.
diff --git a/IntelFrameworkModulePkg/Universal/BdsDxe/BootMaint/BootOption.c b/IntelFrameworkModulePkg/Universal/BdsDxe/BootMaint/BootOption.c
index 5898fb3..6233a11 100644
--- a/IntelFrameworkModulePkg/Universal/BdsDxe/BootMaint/BootOption.c
+++ b/IntelFrameworkModulePkg/Universal/BdsDxe/BootMaint/BootOption.c
@@ -5,7 +5,7 @@
Boot option manipulation
-Copyright (c) 2004 - 2015, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2004 - 2017, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
@@ -1124,7 +1124,7 @@ BOpt_AppendFileName (
// that overlap.
//
StrCpyS (TmpStr, MaxLen, Ptr + 3);
- StrCpyS (LastSlash, MaxLen - (UINTN) (LastSlash - Str), TmpStr);
+ StrCpyS (LastSlash, MaxLen - ((UINTN) LastSlash - (UINTN) Str) / sizeof (CHAR16), TmpStr);
Ptr = LastSlash;
} else if (*Ptr == '\\' && *(Ptr + 1) == '.' && *(Ptr + 2) == '\\') {
//
@@ -1136,7 +1136,7 @@ BOpt_AppendFileName (
// that overlap.
//
StrCpyS (TmpStr, MaxLen, Ptr + 2);
- StrCpyS (Ptr, MaxLen - (UINTN) (Ptr - Str), TmpStr);
+ StrCpyS (Ptr, MaxLen - ((UINTN) Ptr - (UINTN) Str) / sizeof (CHAR16), TmpStr);
Ptr = LastSlash;
} else if (*Ptr == '\\') {
LastSlash = Ptr;
--
1.9.5.msysgit.0
_______________________________________________
edk2-devel mailing list
edk2-devel@lists.01.org
https://lists.01.org/mailman/listinfo/edk2-devel
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
-----Original Message-----
From: Wu, Hao A
Sent: Saturday, February 25, 2017 12:05 PM
To: edk2-devel@lists.01.org
Cc: Wu, Hao A; Fan, Jeff
Subject: [PATCH v3 3/6] IntelFrameworkModulePkg: Refine type cast for pointer subtraction
For pointer subtraction, the result is of type "ptrdiff_t". According to the C11 standard (Committee Draft - April 12, 2011):
"When two pointers are subtracted, both shall point to elements of the same array object, or one past the last element of the array object; the result is the difference of the subscripts of the two array elements. The size of the result is implementation-defined, and its type (a signed integer type) is ptrdiff_t defined in the <stddef.h> header. If the result is not representable in an object of that type, the behavior is undefined."
In our codes, there are cases that the pointer subtraction is not performed by pointers to elements of the same array object. This might lead to potential issues, since the behavior is undefined according to C11 standard.
Also, since the size of type "ptrdiff_t" is implementation-defined. Some static code checkers may warn that the pointer subtraction might underflow first and then being cast to a bigger size. For example:
UINT8 *Ptr1, *Ptr2;
UINTN PtrDiff;
...
PtrDiff = (UINTN) (Ptr1 - Ptr2);
The commit will refine the pointer subtraction expressions by casting each pointer to UINTN first and then perform the subtraction:
PtrDiff = (UINTN) Ptr1 - (UINTN) Ptr2;
Cc: Jeff Fan <jeff.fan@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
---
IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c | 4 ++--
IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c | 4 ++--
IntelFrameworkModulePkg/Library/GenericBdsLib/BdsConsole.c | 4 ++--
IntelFrameworkModulePkg/Library/GenericBdsLib/BdsMisc.c | 4 ++--
IntelFrameworkModulePkg/Library/LegacyBootManagerLib/LegacyBm.c | 4 ++-- IntelFrameworkModulePkg/Universal/BdsDxe/BootMaint/BootOption.c | 6 +++---
6 files changed, 13 insertions(+), 13 deletions(-)
diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
index 8f91a7d..c4c77ec 100644
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
@@ -1,6 +1,6 @@
/** @file
-Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials are licensed and made available under the terms and conditions @@ -318,7 +318,7 @@ GetPciLegacyRom (
break;
}
- if ((UINTN)(RomHeader.Raw - (UINT8 *) *Rom) + Pcir->ImageLength * 512 > *ImageSize) {
+ if (((UINTN)RomHeader.Raw - (UINTN)*Rom) + Pcir->ImageLength * 512
+ > *ImageSize) {
break;
}
diff --git a/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c b/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c
index bba62a8..628424d 100644
--- a/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c
+++ b/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c
@@ -1,7 +1,7 @@
/** @file
BDS Lib functions which relate with create or process the boot option.
-Copyright (c) 2004 - 2016, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2004 - 2017, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials are licensed and made available under the terms and conditions of the BSD License which accompanies this distribution. The full text of the license may be found at @@ -1034,7 +1034,7 @@ BdsCreateDevOrder (
DevOrderPtr->Length = (UINT16) (sizeof (UINT16) + BEVCount * sizeof (UINT16));
DevOrderPtr = (LEGACY_DEV_ORDER_ENTRY *) BdsFillDevOrderBuf (BbsTable, BBS_BEV_DEVICE, BbsCount, DevOrderPtr->Data);
- ASSERT (TotalSize == (UINTN) ((UINT8 *) DevOrderPtr - (UINT8 *) DevOrder));
+ ASSERT (TotalSize == ((UINTN) DevOrderPtr - (UINTN) DevOrder));
//
// Save device order for legacy boot device to variable.
diff --git a/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsConsole.c b/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsConsole.c
index 1020e84..8f273ff 100644
--- a/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsConsole.c
+++ b/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsConsole.c
@@ -1,7 +1,7 @@
/** @file
BDS Lib functions which contain all the code to connect console device
-Copyright (c) 2004 - 2014, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2004 - 2017, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials are licensed and made available under the terms and conditions of the BSD License which accompanies this distribution. The full text of the license may be found at @@ -873,7 +873,7 @@ ConvertBmpToGopBlt (
}
- ImageIndex = (UINTN) (Image - ImageHeader);
+ ImageIndex = (UINTN)Image - (UINTN)ImageHeader;
if ((ImageIndex % 4) != 0) {
//
// Bmp Image starts each row on a 32-bit boundary!
diff --git a/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsMisc.c b/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsMisc.c
index 24c1998..2ba511a 100644
--- a/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsMisc.c
+++ b/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsMisc.c
@@ -1,7 +1,7 @@
/** @file
Misc BDS library function
-Copyright (c) 2004 - 2015, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2004 - 2017, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials are licensed and made available under the terms and conditions of the BSD License which accompanies this distribution. The full text of the license may be found at @@ -669,7 +669,7 @@ BdsLibVariableToOption (
// Get load opion data.
//
LoadOptions = TempPtr;
- LoadOptionsSize = (UINT32) (VariableSize - (UINTN) (TempPtr - Variable));
+ LoadOptionsSize = (UINT32) (VariableSize - ((UINTN)TempPtr -
+ (UINTN)Variable));
//
// The Console variables may have multiple device paths, so make diff --git a/IntelFrameworkModulePkg/Library/LegacyBootManagerLib/LegacyBm.c b/IntelFrameworkModulePkg/Library/LegacyBootManagerLib/LegacyBm.c
index c56a878..080a436 100644
--- a/IntelFrameworkModulePkg/Library/LegacyBootManagerLib/LegacyBm.c
+++ b/IntelFrameworkModulePkg/Library/LegacyBootManagerLib/LegacyBm.c
@@ -3,7 +3,7 @@
and manage the legacy boot option, all legacy boot option is getting from
the legacy BBS table.
-Copyright (c) 2011 - 2016, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2011 - 2017, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials are licensed and made available under the terms and conditions of the BSD License which accompanies this distribution. The full text of the license may be found at @@ -725,7 +725,7 @@ LegacyBmCreateDevOrder (
DevOrderPtr->Length = (UINT16) (sizeof (UINT16) + BEVCount * sizeof (UINT16));
DevOrderPtr = (LEGACY_DEV_ORDER_ENTRY *) LegacyBmFillDevOrderBuf (BbsTable, BBS_BEV_DEVICE, BbsCount, DevOrderPtr->Data);
- ASSERT (TotalSize == (UINTN) ((UINT8 *) DevOrderPtr - (UINT8 *) DevOrder));
+ ASSERT (TotalSize == ((UINTN) DevOrderPtr - (UINTN) DevOrder));
//
// Save device order for legacy boot device to variable.
diff --git a/IntelFrameworkModulePkg/Universal/BdsDxe/BootMaint/BootOption.c b/IntelFrameworkModulePkg/Universal/BdsDxe/BootMaint/BootOption.c
index 5898fb3..6233a11 100644
--- a/IntelFrameworkModulePkg/Universal/BdsDxe/BootMaint/BootOption.c
+++ b/IntelFrameworkModulePkg/Universal/BdsDxe/BootMaint/BootOption.c
@@ -5,7 +5,7 @@
Boot option manipulation
-Copyright (c) 2004 - 2015, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2004 - 2017, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials are licensed and made available under the terms and conditions of the BSD License which accompanies this distribution. The full text of the license may be found at @@ -1124,7 +1124,7 @@ BOpt_AppendFileName (
// that overlap.
//
StrCpyS (TmpStr, MaxLen, Ptr + 3);
- StrCpyS (LastSlash, MaxLen - (UINTN) (LastSlash - Str), TmpStr);
+ StrCpyS (LastSlash, MaxLen - ((UINTN) LastSlash - (UINTN) Str) /
+ sizeof (CHAR16), TmpStr);
Ptr = LastSlash;
} else if (*Ptr == '\\' && *(Ptr + 1) == '.' && *(Ptr + 2) == '\\') {
//
@@ -1136,7 +1136,7 @@ BOpt_AppendFileName (
// that overlap.
//
StrCpyS (TmpStr, MaxLen, Ptr + 2);
- StrCpyS (Ptr, MaxLen - (UINTN) (Ptr - Str), TmpStr);
+ StrCpyS (Ptr, MaxLen - ((UINTN) Ptr - (UINTN) Str) / sizeof
+ (CHAR16), TmpStr);
Ptr = LastSlash;
} else if (*Ptr == '\\') {
LastSlash = Ptr;
--
1.9.5.msysgit.0
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