[PATCH 0/3] kexec: Fix invalid field access

[Breno Leitao]

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.

An initial fix was already landed for arm64[0], and this patchset fixes
the problem on the remaining arm64 code and on riscv, as raised by Mark.

Discussions about this problem could be found at[1][2].

Link: https://lore.kernel.org/all/20250826180742.f2471131255ec1c43683ea07@linux-foundation.org/ [0]
Link: https://lore.kernel.org/all/oninomspajhxp4omtdapxnckxydbk2nzmrix7rggmpukpnzadw@c67o7njgdgm3/ [1]
Link: https://lore.kernel.org/all/20250826-akpm-v1-1-3c831f0e3799@debian.org/ [2]

Signed-off-by: Breno Leitao <leitao at debian.org>
---
Breno Leitao (3):
      arm64: kexec: Initialize kexec_buf struct in load_other_segments()
      riscv: kexec: Initialize kexec_buf struct
      s390: kexec: Initialize kexec_buf struct

 arch/arm64/kernel/machine_kexec_file.c | 2 +-
 arch/riscv/kernel/kexec_elf.c          | 4 ++--
 arch/riscv/kernel/kexec_image.c        | 2 +-
 arch/riscv/kernel/machine_kexec_file.c | 2 +-
 arch/s390/kernel/kexec_elf.c           | 2 +-
 arch/s390/kernel/kexec_image.c         | 2 +-
 arch/s390/kernel/machine_kexec_file.c  | 6 +++---
 7 files changed, 10 insertions(+), 10 deletions(-)
---
base-commit: 3c642997252eef4449cb6b6e02af3dc22515d817
change-id: 20250827-kbuf_all-b9d55c9291eb

Best regards,
--  
Breno Leitao <leitao at debian.org>