linux-kernel - [PATCH 2/3] riscv: kexec: Initialize kexec

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Message-Id: <20250827-kbuf_all-v1-2-1df9882bb01a@debian.org>
Date: Wed, 27 Aug 2025 03:42:22 -0700
From: Breno Leitao <leitao@...ian.org>
To: Catalin Marinas <catalin.marinas@....com>, 
 Will Deacon <will@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, 
 Baoquan He <bhe@...hat.com>, Coiby Xu <coxu@...hat.com>, 
 Paul Walmsley <paul.walmsley@...ive.com>, 
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
 Alexandre Ghiti <alex@...ti.fr>, Heiko Carstens <hca@...ux.ibm.com>, 
 Vasily Gorbik <gor@...ux.ibm.com>, 
 Alexander Gordeev <agordeev@...ux.ibm.com>, 
 Christian Borntraeger <borntraeger@...ux.ibm.com>, 
 Sven Schnelle <svens@...ux.ibm.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org, 
 Breno Leitao <leitao@...ian.org>, kernel-team@...a.com
Subject: [PATCH 2/3] riscv: kexec: Initialize kexec_buf struct

The kexec_buf structure was previously declared without initialization.
commit bf454ec31add ("kexec_file: allow to place kexec_buf randomly")
added a field that is always read but not consistently populated by all
architectures. This un-initialized field will contain garbage.

This is also triggering a UBSAN warning when the uninitialized data was
accessed:

	------------[ cut here ]------------
	UBSAN: invalid-load in ./include/linux/kexec.h:210:10
	load of value 252 is not a valid value for type '_Bool'

Zero-initializing kexec_buf at declaration ensures all fields are
cleanly set, preventing future instances of uninitialized memory being
used.

Fixes: bf454ec31add ("kexec_file: allow to place kexec_buf randomly")
Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 arch/riscv/kernel/kexec_elf.c          | 4 ++--
 arch/riscv/kernel/kexec_image.c        | 2 +-
 arch/riscv/kernel/machine_kexec_file.c | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/kernel/kexec_elf.c b/arch/riscv/kernel/kexec_elf.c
index 56444c7bd34eb..531d348db84d7 100644
--- a/arch/riscv/kernel/kexec_elf.c
+++ b/arch/riscv/kernel/kexec_elf.c
@@ -28,7 +28,7 @@ static int riscv_kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
 	int i;
 	int ret = 0;
 	size_t size;
-	struct kexec_buf kbuf;
+	struct kexec_buf kbuf = {};
 	const struct elf_phdr *phdr;
 
 	kbuf.image = image;
@@ -66,7 +66,7 @@ static int elf_find_pbase(struct kimage *image, unsigned long kernel_len,
 {
 	int i;
 	int ret;
-	struct kexec_buf kbuf;
+	struct kexec_buf kbuf = {};
 	const struct elf_phdr *phdr;
 	unsigned long lowest_paddr = ULONG_MAX;
 	unsigned long lowest_vaddr = ULONG_MAX;
diff --git a/arch/riscv/kernel/kexec_image.c b/arch/riscv/kernel/kexec_image.c
index 26a81774a78a3..8f2eb900910b1 100644
--- a/arch/riscv/kernel/kexec_image.c
+++ b/arch/riscv/kernel/kexec_image.c
@@ -41,7 +41,7 @@ static void *image_load(struct kimage *image,
 	struct riscv_image_header *h;
 	u64 flags;
 	bool be_image, be_kernel;
-	struct kexec_buf kbuf;
+	struct kexec_buf kbuf = {};
 	int ret;
 
 	/* Check Image header */
diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
index e36104af2e247..b9eb41b0a9751 100644
--- a/arch/riscv/kernel/machine_kexec_file.c
+++ b/arch/riscv/kernel/machine_kexec_file.c
@@ -261,7 +261,7 @@ int load_extra_segments(struct kimage *image, unsigned long kernel_start,
 	int ret;
 	void *fdt;
 	unsigned long initrd_pbase = 0UL;
-	struct kexec_buf kbuf;
+	struct kexec_buf kbuf = {};
 	char *modified_cmdline = NULL;
 
 	kbuf.image = image;

-- 
2.47.3