linux-kernel - [PATCH 3/3] s390: kexec: Initialize kexec

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Message-Id: <20250827-kbuf_all-v1-3-1df9882bb01a@debian.org>
Date: Wed, 27 Aug 2025 03:42:23 -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 3/3] s390: 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/s390/kernel/kexec_elf.c          | 2 +-
 arch/s390/kernel/kexec_image.c        | 2 +-
 arch/s390/kernel/machine_kexec_file.c | 6 +++---
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/s390/kernel/kexec_elf.c b/arch/s390/kernel/kexec_elf.c
index 4d364de437992..143e34a4eca57 100644
--- a/arch/s390/kernel/kexec_elf.c
+++ b/arch/s390/kernel/kexec_elf.c
@@ -16,7 +16,7 @@
 static int kexec_file_add_kernel_elf(struct kimage *image,
 				     struct s390_load_data *data)
 {
-	struct kexec_buf buf;
+	struct kexec_buf buf = {};
 	const Elf_Ehdr *ehdr;
 	const Elf_Phdr *phdr;
 	Elf_Addr entry;
diff --git a/arch/s390/kernel/kexec_image.c b/arch/s390/kernel/kexec_image.c
index a32ce8bea745c..9a439175723ca 100644
--- a/arch/s390/kernel/kexec_image.c
+++ b/arch/s390/kernel/kexec_image.c
@@ -16,7 +16,7 @@
 static int kexec_file_add_kernel_image(struct kimage *image,
 				       struct s390_load_data *data)
 {
-	struct kexec_buf buf;
+	struct kexec_buf buf = {};
 
 	buf.image = image;
 
diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c
index c2bac14dd668a..a36d7311c6683 100644
--- a/arch/s390/kernel/machine_kexec_file.c
+++ b/arch/s390/kernel/machine_kexec_file.c
@@ -129,7 +129,7 @@ static int kexec_file_update_purgatory(struct kimage *image,
 static int kexec_file_add_purgatory(struct kimage *image,
 				    struct s390_load_data *data)
 {
-	struct kexec_buf buf;
+	struct kexec_buf buf = {};
 	int ret;
 
 	buf.image = image;
@@ -152,7 +152,7 @@ static int kexec_file_add_purgatory(struct kimage *image,
 static int kexec_file_add_initrd(struct kimage *image,
 				 struct s390_load_data *data)
 {
-	struct kexec_buf buf;
+	struct kexec_buf buf = {};
 	int ret;
 
 	buf.image = image;
@@ -184,7 +184,7 @@ static int kexec_file_add_ipl_report(struct kimage *image,
 {
 	__u32 *lc_ipl_parmblock_ptr;
 	unsigned int len, ncerts;
-	struct kexec_buf buf;
+	struct kexec_buf buf = {};
 	unsigned long addr;
 	void *ptr, *end;
 	int ret;

-- 
2.47.3