linux-kernel - [PATCH -fixes] riscv: Do not use fortify in early code

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Message-Id: <20241009072749.45006-1-alexghiti@rivosinc.com>
Date: Wed,  9 Oct 2024 09:27:49 +0200
From: Alexandre Ghiti <alexghiti@...osinc.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Heiko Stuebner <heiko@...ech.de>,
	Alexandre Ghiti <alexghiti@...osinc.com>,
	Björn Töpel <bjorn@...osinc.com>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Cc: Jason Montleon <jmontleo@...hat.com>,
	stable@...r.kernel.org
Subject: [PATCH -fixes] riscv: Do not use fortify in early code

Early code designates the code executed when the MMU is not yet enabled,
and this comes with some limitations (see
Documentation/arch/riscv/boot.rst, section "Pre-MMU execution").

FORTIFY_SOURCE must be disabled then since it can trigger kernel panics
as reported in [1].

Reported-by: Jason Montleon <jmontleo@...hat.com>
Closes: https://lore.kernel.org/linux-riscv/CAJD_bPJes4QhmXY5f63GHV9B9HFkSCoaZjk-qCT2NGS7Q9HODg@mail.gmail.com/ [1]
Fixes: a35707c3d850 ("riscv: add memory-type errata for T-Head")
Fixes: 26e7aacb83df ("riscv: Allow to downgrade paging mode from the command line")
Cc: stable@...r.kernel.org
Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
---
 arch/riscv/errata/Makefile    | 6 ++++++
 arch/riscv/kernel/Makefile    | 5 +++++
 arch/riscv/kernel/pi/Makefile | 6 +++++-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/errata/Makefile b/arch/riscv/errata/Makefile
index 8a2739485123..f0da9d7b39c3 100644
--- a/arch/riscv/errata/Makefile
+++ b/arch/riscv/errata/Makefile
@@ -2,6 +2,12 @@ ifdef CONFIG_RELOCATABLE
 KBUILD_CFLAGS += -fno-pie
 endif
 
+ifdef CONFIG_RISCV_ALTERNATIVE_EARLY
+ifdef CONFIG_FORTIFY_SOURCE
+KBUILD_CFLAGS += -D__NO_FORTIFY
+endif
+endif
+
 obj-$(CONFIG_ERRATA_ANDES) += andes/
 obj-$(CONFIG_ERRATA_SIFIVE) += sifive/
 obj-$(CONFIG_ERRATA_THEAD) += thead/
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 7f88cc4931f5..69dc8aaab3fb 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -36,6 +36,11 @@ KASAN_SANITIZE_alternative.o := n
 KASAN_SANITIZE_cpufeature.o := n
 KASAN_SANITIZE_sbi_ecall.o := n
 endif
+ifdef CONFIG_FORTIFY_SOURCE
+CFLAGS_alternative.o += -D__NO_FORTIFY
+CFLAGS_cpufeature.o += -D__NO_FORTIFY
+CFLAGS_sbi_ecall.o += -D__NO_FORTIFY
+endif
 endif
 
 extra-y += vmlinux.lds
diff --git a/arch/riscv/kernel/pi/Makefile b/arch/riscv/kernel/pi/Makefile
index d5bf1bc7de62..81d69d45c06c 100644
--- a/arch/riscv/kernel/pi/Makefile
+++ b/arch/riscv/kernel/pi/Makefile
@@ -16,8 +16,12 @@ KBUILD_CFLAGS	:= $(filter-out $(CC_FLAGS_LTO), $(KBUILD_CFLAGS))
 KBUILD_CFLAGS	+= -mcmodel=medany
 
 CFLAGS_cmdline_early.o += -D__NO_FORTIFY
-CFLAGS_lib-fdt_ro.o += -D__NO_FORTIFY
 CFLAGS_fdt_early.o += -D__NO_FORTIFY
+# lib/string.c already defines __NO_FORTIFY
+CFLAGS_ctype.o += -D__NO_FORTIFY
+CFLAGS_lib-fdt.o += -D__NO_FORTIFY
+CFLAGS_lib-fdt_ro.o += -D__NO_FORTIFY
+CFLAGS_archrandom_early.o += -D__NO_FORTIFY
 
 $(obj)/%.pi.o: OBJCOPYFLAGS := --prefix-symbols=__pi_ \
 			       --remove-section=.note.gnu.property \
-- 
2.39.2