RH covscan justifiedly reports that accessing
"EFI_COMMON_SECTION_HEADER.Size", which is of type UINT8[3], through a
(UINT32*), is undefined behavior:
> Error: OVERRUN (CWE-119):
> edk2-89910a39dcfd/OvmfPkg/Sec/SecMain.c:178: overrun-local: Overrunning
> array of 3 bytes at byte offset 3 by dereferencing pointer
> "(UINT32 *)((EFI_COMMON_SECTION_HEADER *)(UINTN)Section)->Size".
> # 176| Section = (EFI_COMMON_SECTION_HEADER*)(UINTN) CurrentAddress;
> # 177|
> # 178|-> Size = SECTION_SIZE (Section);
> # 179| if (Size < sizeof (*Section)) {
> # 180| return EFI_VOLUME_CORRUPTED;
Fix this by introducing EFI_COMMON_SECTION_HEADER_UNION, and expressing
SECTION_SIZE() in terms of "EFI_COMMON_SECTION_HEADER_UNION.Uint32".
Cc: Liming Gao <liming....@intel.com>
Cc: Michael D Kinney <michael.d.kin...@intel.com>
Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=1710
Issue: scan-1007.txt
Signed-off-by: Laszlo Ersek <ler...@redhat.com>
---
MdePkg/Include/Pi/PiFirmwareFile.h | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/MdePkg/Include/Pi/PiFirmwareFile.h
b/MdePkg/Include/Pi/PiFirmwareFile.h
index a9f3bcc4eb8e..4fce8298d1c0 100644
--- a/MdePkg/Include/Pi/PiFirmwareFile.h
+++ b/MdePkg/Include/Pi/PiFirmwareFile.h
@@ -229,16 +229,24 @@ typedef struct {
///
UINT8 Size[3];
EFI_SECTION_TYPE Type;
///
/// Declares the section type.
///
} EFI_COMMON_SECTION_HEADER;
+///
+/// Union that permits accessing EFI_COMMON_SECTION_HEADER as a UINT32 object.
+///
+typedef union {
+ EFI_COMMON_SECTION_HEADER Hdr;
+ UINT32 Uint32;
+} EFI_COMMON_SECTION_HEADER_UNION;
+
typedef struct {
///
/// A 24-bit unsigned integer that contains the total size of the section in
bytes,
/// including the EFI_COMMON_SECTION_HEADER.
///
UINT8 Size[3];
EFI_SECTION_TYPE Type;
@@ -476,17 +484,17 @@ typedef struct {
/// A UINT16 that represents a particular build. Subsequent builds have
monotonically
/// increasing build numbers relative to earlier builds.
///
UINT16 BuildNumber;
CHAR16 VersionString[1];
} EFI_VERSION_SECTION2;
#define SECTION_SIZE(SectionHeaderPtr) \
- ((UINT32) (*((UINT32 *) ((EFI_COMMON_SECTION_HEADER *) (UINTN)
SectionHeaderPtr)->Size) & 0x00ffffff))
+ (((EFI_COMMON_SECTION_HEADER_UNION *) (UINTN) (SectionHeaderPtr))->Uint32
& 0x00ffffff)
#define IS_SECTION2(SectionHeaderPtr) \
(SECTION_SIZE (SectionHeaderPtr) == 0x00ffffff)
#define SECTION2_SIZE(SectionHeaderPtr) \
(((EFI_COMMON_SECTION_HEADER2 *) (UINTN) SectionHeaderPtr)->ExtendedSize)
#pragma pack()
--
2.19.1.3.g30247aa5d201
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