Re: [PATCH v4 6/7] x86/crash: pass dm crypt keys to kdump kernel

Baoquan He
2024-06-07T09:58:12Z

On 05/23/24 at 01:04pm, Coiby Xu wrote:
> 1st kernel will build up the kernel command parameter dmcryptkeys as
> similar to elfcorehdr to pass the memory address of the stored info of
> dm crypt key to kdump kernel.
>
> Signed-off-by: Coiby Xu <coxu@redhat.com>
> ---
> arch/x86/kernel/crash.c | 15 ++++++++++++++-
> arch/x86/kernel/kexec-bzimage64.c | 7 +++++++
> 2 files changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
> index f06501445cd9..74b3844ae53c 100644
> --- a/arch/x86/kernel/crash.c
> +++ b/arch/x86/kernel/crash.c
> @@ -266,6 +266,7 @@ static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
> unsigned long long mend)
> {
> unsigned long start, end;
> + int r;
~?

r is only to contain the returned value? Then you can call it ret as
many do in kernel code.

>
> cmem->ranges[0].start = mstart;
> cmem->ranges[0].end = mend;
> @@ -274,7 +275,19 @@ static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
> /* Exclude elf header region */
> start = image->elf_load_addr;
> end = start + image->elf_headers_sz - 1;
> - return crash_exclude_mem_range(cmem, start, end);
> + r = crash_exclude_mem_range(cmem, start, end);
> +
> + if (r)
> + return r;
> +
> + /* Exclude dm crypt keys region */
> + if (image->dm_crypt_keys_addr) {
> + start = image->dm_crypt_keys_addr;
> + end = start + image->dm_crypt_keys_sz - 1;
> + return crash_exclude_mem_range(cmem, start, end);
> + }

You need adjust the array length of cmem->ranges[], I believe you will
cause the array overflow because the keys are randomly set and mostly
will be in the middle of crashkernel region.

> +
> + return r;
> }
>
> /* Prepare memory map for crash dump kernel */