RH covscan emits the following false positive:
> Error: CLANG_WARNING:
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c:182:14:
> warning: Dereference of undefined pointer value
> # Status = FwVol->ReadSection (
> # ^~~~~~~~~~~~~~~~~~
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c:164:7: note:
> Assuming the condition is false
> # if (QemuDetected ()) {
> # ^~~~~~~~~~~~~~~
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c:164:3: note:
> Taking false branch
> # if (QemuDetected ()) {
> # ^
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c:174:3: note:
> Taking false branch
> # if (EFI_ERROR (Status)) {
> # ^
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c:180:10: note:
> Assuming 'Status' is equal to EFI_SUCCESS
> # while (Status == EFI_SUCCESS) {
> # ^~~~~~~~~~~~~~~~~~~~~
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c:180:3: note:
> Loop condition is true. Entering loop body
> # while (Status == EFI_SUCCESS) {
> # ^
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c:182:14: note:
> Dereference of undefined pointer value
> # Status = FwVol->ReadSection (
> # ^~~~~~~~~~~~~~~~~~
> # 180| while (Status == EFI_SUCCESS) {
> # 181|
> # 182|-> Status = FwVol->ReadSection (
> # 183| FwVol,
> # 184| (EFI_GUID*)PcdGetPtr
> (PcdAcpiTableStorageFile),
This is invalid because LocateFvInstanceWithTables() sets FwVol on
success.
Suppress the message by:
- assigning FwVol NULL first (this would replace the original report with
"nullptr deref"),
- asserting that FwVol is no longer NULL, on success.
What's important here is that ASSERT() ends with ANALYZER_UNREACHABLE() on
failure.
Cc: Ard Biesheuvel <[email protected]>
Cc: Jordan Justen <[email protected]>
Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=1710
Issue: scan-0991.txt
Signed-off-by: Laszlo Ersek <[email protected]>
---
OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c
b/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c
index f2c49953950b..2b529d58a15c 100644
--- a/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c
+++ b/OvmfPkg/AcpiPlatformDxe/AcpiPlatform.c
@@ -156,23 +156,30 @@ InstallOvmfFvTables (
TableHandle = 0;
if (QemuDetected ()) {
TableInstallFunction = QemuInstallAcpiTable;
} else {
TableInstallFunction = InstallAcpiTable;
}
+ //
+ // set FwVol (and use an ASSERT() below) to suppress incorrect
+ // compiler/analyzer warnings
+ //
+ FwVol = NULL;
//
// Locate the firmware volume protocol
//
Status = LocateFvInstanceWithTables (&FwVol);
if (EFI_ERROR (Status)) {
return EFI_ABORTED;
}
+ ASSERT (FwVol != NULL);
+
//
// Read tables from the storage file.
//
while (Status == EFI_SUCCESS) {
Status = FwVol->ReadSection (
FwVol,
(EFI_GUID*)PcdGetPtr (PcdAcpiTableStorageFile),
--
2.19.1.3.g30247aa5d201
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