[PATCH v2] arm64: kernel: initialize missing kexec_buf->random field

[Yeoreum Yun]

Gentle ping in case of forgotten.

On Mon, Dec 01, 2025 at 10:51:18AM +0000, Yeoreum Yun wrote:
> Commit bf454ec31add ("kexec_file: allow to place kexec_buf randomly")
> introduced the kexec_buf->random field to enable random placement of
> kexec_buf.
>
> However, this field was never properly initialized for kexec images
> that do not need to be placed randomly, leading to the following UBSAN
> warning:
>
> [  +0.364528] ------------[ cut here ]------------
> [  +0.000019] UBSAN: invalid-load in ./include/linux/kexec.h:210:12
> [  +0.000131] load of value 2 is not a valid value for type 'bool' (aka '_Bool')
> [  +0.000003] CPU: 4 UID: 0 PID: 927 Comm: kexec Not tainted 6.18.0-rc7+ #3 PREEMPT(full)
> [  +0.000002] Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
> [  +0.000000] Call trace:
> [  +0.000001]  show_stack+0x24/0x40 (C)
> [  +0.000006]  __dump_stack+0x28/0x48
> [  +0.000002]  dump_stack_lvl+0x7c/0xb0
> [  +0.000002]  dump_stack+0x18/0x34
> [  +0.000001]  ubsan_epilogue+0x10/0x50
> [  +0.000002]  __ubsan_handle_load_invalid_value+0xc8/0xd0
> [  +0.000003]  locate_mem_hole_callback+0x28c/0x2a0
> [  +0.000003]  kexec_locate_mem_hole+0xf4/0x2f0
> [  +0.000001]  kexec_add_buffer+0xa8/0x178
> [  +0.000002]  image_load+0xf0/0x258
> [  +0.000001]  __arm64_sys_kexec_file_load+0x510/0x718
> [  +0.000002]  invoke_syscall+0x68/0xe8
> [  +0.000001]  el0_svc_common+0xb0/0xf8
> [  +0.000002]  do_el0_svc+0x28/0x48
> [  +0.000001]  el0_svc+0x40/0xe8
> [  +0.000002]  el0t_64_sync_handler+0x84/0x140
> [  +0.000002]  el0t_64_sync+0x1bc/0x1c0
>
> To address this, initialise kexec_buf->random field properly.
>
> Fixes: bf454ec31add ("kexec_file: allow to place kexec_buf randomly")
> Suggested-by: Breno Leitao <leitao at debian.org>
> Cc: <stable at vger.kernel.org>
> Signed-off-by: Yeoreum Yun <yeoreum.yun at arm.com>
> ---
>  arch/arm64/kernel/kexec_image.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c
> index 532d72ea42ee..b70f4df15a1a 100644
> --- a/arch/arm64/kernel/kexec_image.c
> +++ b/arch/arm64/kernel/kexec_image.c
> @@ -41,7 +41,7 @@ static void *image_load(struct kimage *image,
>  	struct arm64_image_header *h;
>  	u64 flags, value;
>  	bool be_image, be_kernel;
> -	struct kexec_buf kbuf;
> +	struct kexec_buf kbuf = {};
>  	unsigned long text_offset, kernel_segment_number;
>  	struct kexec_segment *kernel_segment;
>  	int ret;
> --
> LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
>

--
Sincerely,
Yeoreum Yun