linux-kernel - [PATCH 5.0 088/101] KVM: selftests: disable stack protector for all KVM tests

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Date:   Thu,  2 May 2019 17:21:30 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "Sasha Levin (Microsoft)" <sashal@...nel.org>
Subject: [PATCH 5.0 088/101] KVM: selftests: disable stack protector for all KVM tests

[ Upstream commit ffac839d040619847217647434b2b02469926871 ]

Since 4.8.3, gcc has enabled -fstack-protector by default.  This is
problematic for the KVM selftests as they do not configure fs or gs
segments (the stack canary is pulled from fs:0x28).  With the default
behavior, gcc will insert a stack canary on any function that creates
buffers of 8 bytes or more.  As a result, ucall() will hit a triple
fault shutdown due to reading a bad fs segment when inserting its
stack canary, i.e. every test fails with an unexpected SHUTDOWN.

Fixes: 14c47b7530e2d ("kvm: selftests: introduce ucall")
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sasha Levin (Microsoft) <sashal@...nel.org>
---
 tools/testing/selftests/kvm/Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 212b8f0032ae..cb4a992d6dd3 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -28,8 +28,8 @@ LIBKVM += $(LIBKVM_$(UNAME_M))
 INSTALL_HDR_PATH = $(top_srcdir)/usr
 LINUX_HDR_PATH = $(INSTALL_HDR_PATH)/include/
 LINUX_TOOL_INCLUDE = $(top_srcdir)/tools/include
-CFLAGS += -O2 -g -std=gnu99 -no-pie -I$(LINUX_TOOL_INCLUDE) -I$(LINUX_HDR_PATH) -Iinclude -I$(<D) -Iinclude/$(UNAME_M) -I..
-LDFLAGS += -pthread
+CFLAGS += -O2 -g -std=gnu99 -fno-stack-protector -fno-PIE -I$(LINUX_TOOL_INCLUDE) -I$(LINUX_HDR_PATH) -Iinclude -I$(<D) -Iinclude/$(UNAME_M) -I..
+LDFLAGS += -pthread -no-pie
 
 # After inclusion, $(OUTPUT) is defined and
 # $(TEST_GEN_PROGS) starts with $(OUTPUT)/
-- 
2.19.1