From: "Laszlo Ersek" <lersek@redhat.com>
To: edk2-devel-groups-io <devel@edk2.groups.io>
Cc: Anthony Perard <anthony.perard@citrix.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Jordan Justen <jordan.l.justen@intel.com>,
Julien Grall <julien.grall@arm.com>
Subject: [PATCH 09/10] OvmfPkg/AcpiPlatformDxe: catch theoretical nullptr deref in Xen code
Date: Sat, 13 Apr 2019 01:31:27 +0200 [thread overview]
Message-ID: <20190412233128.4756-10-lersek@redhat.com> (raw)
In-Reply-To: <20190412233128.4756-1-lersek@redhat.com>
RH covscan justifiedly reports a path through InstallXenTables() where
DsdtTable can technically remain NULL.
If this occurs in practice, then the guest and the VMM are out of sync on
the interface contract. Catch the situation with a code snippet that halts
in RELEASE builds, and in DEBUG builds lets the platform DSC control the
assert disposition first (i.e. CPU exception, deadloop, or nothing).
> Error: CLANG_WARNING:
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/Xen.c:309:14: warning: Access
> to field 'Length' results in a dereference of a null pointer (loaded
> from variable 'DsdtTable')
> # DsdtTable->Length,
> # ^~~~~~~~~
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/Xen.c:154:3: note: Null
> pointer value stored to 'DsdtTable'
> # DsdtTable = NULL;
> # ^~~~~~~~~~~~~~~~~~
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/Xen.c:162:3: note: Taking
> false branch
> # if (EFI_ERROR (Status)) {
> # ^
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/Xen.c:170:7: note: Assuming
> the condition is false
> # if (XenAcpiRsdpStructurePtr->XsdtAddress) {
> # ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/Xen.c:170:3: note: Taking
> false branch
> # if (XenAcpiRsdpStructurePtr->XsdtAddress) {
> # ^
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/Xen.c:220:12: note: Assuming
> the condition is false
> # else if (XenAcpiRsdpStructurePtr->RsdtAddress) {
> # ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/Xen.c:220:8: note: Taking
> false branch
> # else if (XenAcpiRsdpStructurePtr->RsdtAddress) {
> # ^
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/Xen.c:274:3: note: Taking
> false branch
> # if (Fadt2Table) {
> # ^
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/Xen.c:288:8: note: Taking
> false branch
> # else if (Fadt1Table) {
> # ^
> edk2-89910a39dcfd/OvmfPkg/AcpiPlatformDxe/Xen.c:309:14: note: Access to
> field 'Length' results in a dereference of a null pointer (loaded from
> variable 'DsdtTable')
> # DsdtTable->Length,
> # ^~~~~~~~~
> # 307| AcpiProtocol,
> # 308| DsdtTable,
> # 309|-> DsdtTable->Length,
> # 310| &TableHandle
> # 311| );
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Julien Grall <julien.grall@arm.com>
Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=1710
Issue: scan-0993.txt
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
OvmfPkg/AcpiPlatformDxe/Xen.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/OvmfPkg/AcpiPlatformDxe/Xen.c b/OvmfPkg/AcpiPlatformDxe/Xen.c
index c8f275a8ee84..b21d3db74dc8 100644
--- a/OvmfPkg/AcpiPlatformDxe/Xen.c
+++ b/OvmfPkg/AcpiPlatformDxe/Xen.c
@@ -295,18 +295,25 @@ InstallXenTables (
&TableHandle
);
if (EFI_ERROR (Status)) {
return Status;
}
}
//
- // Install DSDT table.
+ // Install DSDT table. If we reached this point without finding the DSDT,
+ // then we're out of sync with the hypervisor, and cannot continue.
//
+ if (DsdtTable == NULL) {
+ DEBUG ((DEBUG_ERROR, "%a: no DSDT found\n", __FUNCTION__));
+ ASSERT (FALSE);
+ CpuDeadLoop ();
+ }
+
Status = InstallAcpiTable (
AcpiProtocol,
DsdtTable,
DsdtTable->Length,
&TableHandle
);
if (EFI_ERROR (Status)) {
return Status;
--
2.19.1.3.g30247aa5d201
next prev parent reply other threads:[~2019-04-12 23:31 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-12 23:31 [PATCH 00/10] patches for some warnings raised by "RH covscan" Laszlo Ersek
2019-04-12 23:31 ` [PATCH 01/10] MdePkg/PiFirmwareFile: express IS_SECTION2 in terms of SECTION_SIZE Laszlo Ersek
2019-04-15 17:01 ` [edk2-devel] " Philippe Mathieu-Daudé
2019-04-12 23:31 ` [PATCH 02/10] MdePkg/PiFirmwareFile: fix undefined behavior in SECTION_SIZE Laszlo Ersek
2019-04-14 7:19 ` [edk2-devel] " Jordan Justen
2019-04-15 16:15 ` Laszlo Ersek
2019-04-16 8:28 ` Liming Gao
2019-04-16 9:04 ` Jordan Justen
2019-04-16 10:59 ` Laszlo Ersek
2019-04-16 16:50 ` Philippe Mathieu-Daudé
2019-04-17 10:08 ` Laszlo Ersek
2019-04-16 18:48 ` Jordan Justen
2019-04-16 23:25 ` Andrew Fish
2019-04-17 10:29 ` Laszlo Ersek
2019-04-17 11:44 ` Andrew Fish
2019-04-17 14:59 ` Laszlo Ersek
2019-04-17 19:35 ` Jordan Justen
2019-04-18 9:38 ` Laszlo Ersek
2019-04-18 15:18 ` Liming Gao
2019-04-17 10:01 ` Laszlo Ersek
2019-04-12 23:31 ` [PATCH 03/10] BaseTools/PiFirmwareFile: " Laszlo Ersek
2019-04-12 23:31 ` [PATCH 04/10] MdePkg/PiFirmwareFile: fix undefined behavior in FFS_FILE_SIZE Laszlo Ersek
2019-04-15 17:23 ` [edk2-devel] " Philippe Mathieu-Daudé
2019-04-17 17:52 ` Michael D Kinney
2019-04-17 18:31 ` Michael D Kinney
2019-04-18 9:06 ` Laszlo Ersek
2019-04-17 18:31 ` Andrew Fish
2019-04-17 18:36 ` Michael D Kinney
2019-04-18 8:48 ` Laszlo Ersek
2019-04-18 8:45 ` Laszlo Ersek
2019-04-18 23:12 ` Laszlo Ersek
2019-04-18 17:20 ` Philippe Mathieu-Daudé
2019-04-18 17:59 ` Michael D Kinney
2019-04-18 18:12 ` Philippe Mathieu-Daudé
2019-04-12 23:31 ` [PATCH 05/10] OvmfPkg/Sec: fix out-of-bounds reads Laszlo Ersek
2019-04-15 17:24 ` [edk2-devel] " Philippe Mathieu-Daudé
2019-04-12 23:31 ` [PATCH 06/10] OvmfPkg/QemuVideoDxe: avoid arithmetic on null pointer Laszlo Ersek
2019-04-12 23:31 ` [PATCH 07/10] OvmfPkg/AcpiPlatformDxe: suppress invalid "deref of undef pointer" warning Laszlo Ersek
2019-04-15 17:26 ` [edk2-devel] " Philippe Mathieu-Daudé
2019-04-12 23:31 ` [PATCH 08/10] OvmfPkg: suppress "Value stored to ... is never read" analyzer warnings Laszlo Ersek
2019-04-14 8:03 ` [edk2-devel] " Jordan Justen
2019-04-15 16:25 ` Laszlo Ersek
2019-04-16 9:26 ` Jordan Justen
2019-04-16 11:44 ` Laszlo Ersek
2019-04-12 23:31 ` Laszlo Ersek [this message]
2019-04-15 17:28 ` [edk2-devel] [PATCH 09/10] OvmfPkg/AcpiPlatformDxe: catch theoretical nullptr deref in Xen code Philippe Mathieu-Daudé
2019-04-12 23:31 ` [PATCH 10/10] OvmfPkg/BasePciCapLib: suppress invalid "nullptr deref" warning Laszlo Ersek
2019-04-15 17:31 ` [edk2-devel] " Philippe Mathieu-Daudé
2019-04-16 11:01 ` Laszlo Ersek
2019-04-12 23:36 ` [PATCH 00/10] patches for some warnings raised by "RH covscan" Ard Biesheuvel
2019-04-15 16:16 ` Laszlo Ersek
2019-04-18 14:20 ` [edk2-devel] " Laszlo Ersek
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