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

Hi Breno,

On 8/27/25 12:42, Breno Leitao wrote:

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/ (local) [0]
Link: https://lore.kernel.org/all/oninomspajhxp4omtdapxnckxydbk2nzmrix7rggmpukpnzadw@c67o7njgdgm3/ (local) [1]
Link: https://lore.kernel.org/all/20250826-akpm-v1-1-3c831f0e3799@debian.org/ (local) [2]

Signed-off-by: Breno Leitao <leitao@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 [off-list ref]

I see that the commit those patches fix is in 6.16 so we should add cc: 
stable.

And who should merge those patches? Should we do it on a per-arch basis?

Thanks,

Alex

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