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SubjectRe: [PATCH] x86, kdump: Fix efi=noruntime NULL pointer dereference
Apologize for late reply, I'm occupied with something else.

On 08/10/18 at 07:39pm, Mike Galbraith wrote:
> On Fri, 2018-08-10 at 18:28 +0800, Dave Young wrote:
> >
> > > @@ -250,8 +253,10 @@ setup_boot_parameters(struct kimage *image, struct boot_params *params,
> > >
> > > #ifdef CONFIG_EFI
> > > /* Setup EFI state */
> > > - setup_efi_state(params, params_load_addr, efi_map_offset, efi_map_sz,
> > > + ret = setup_efi_state(params, params_load_addr, efi_map_offset, efi_map_sz,
> > > efi_setup_data_offset);
> > > + if (ret)
> >
> > Here should check efi_enabled(EFI_BOOT) && ret
>
> Patch with that works for me.
>
> > In case efi boot we need the efi info set correctly, or one need pass
> > acpi_rsdp= in kernel cmdline param.
> >
> > Still not sure how to allow one to workaround it by using acpi_rsdp=
> > param with kexec_file_load..
>
> Does this improve things, and plug the no boot hole?

Would you mind to tune my patch with some acpi_rsdp checking and add
some error message in case kexec load failure? Eg. suggest people to use
append acpi_rsdp for noefi booting etc.

I'm still not very satisfied with the code cleanup, ideally we should add a
separate kbuf for efi stuff, so that we can isolate the efi_map_sz
efi_setup_data_offset, and efi_map_offset initialization only when
necessary. Anyway the cleanup can be a separate patch.

>
> x86, kdump: cleanup efi setup data handling a bit
>
> 1. Remove efi specific variables from bzImage64_load() other than the
> one it needs, efi_map_sz, passing it and params_cmdline_sz on to efi
> setup functions, giving them all they need without duplication.
>
> 2. Only allocate space for efi setup data when a 1:1 mapping is available.
> Bail early with -ENODEV if not available, but is required to boot, and
> acpi_rsdp= was not passed on the command line.
>
> 3. Use the proper config dependency to isolate efi setup functions,
> adding a !EFI_RUNTIME_MAP stub for setup_efi_state().
>
> 4. Change efi functions that cannot fail to void.
>
> Signed-off-by: Mike Galbraith <efault@gmx.de>
> ---
> arch/x86/kernel/kexec-bzimage64.c | 99 +++++++++++++++++---------------------
> 1 file changed, 45 insertions(+), 54 deletions(-)
>
> --- a/arch/x86/kernel/kexec-bzimage64.c
> +++ b/arch/x86/kernel/kexec-bzimage64.c
> @@ -112,35 +112,32 @@ static int setup_e820_entries(struct boo
> return 0;
> }
>
> -#ifdef CONFIG_EFI
> -static int setup_efi_info_memmap(struct boot_params *params,
> +#ifdef CONFIG_EFI_RUNTIME_MAP
> +static void setup_efi_info_memmap(struct boot_params *params,
> unsigned long params_load_addr,
> - unsigned int efi_map_offset,
> + unsigned int params_cmdline_sz,
> unsigned int efi_map_sz)
> {
> - void *efi_map = (void *)params + efi_map_offset;
> - unsigned long efi_map_phys_addr = params_load_addr + efi_map_offset;
> + void *efi_map = (void *)params + params_cmdline_sz;
> + unsigned long efi_map_phys_addr = params_load_addr + params_cmdline_sz;
> struct efi_info *ei = &params->efi_info;
>
> - if (!efi_map_sz)
> - return -EINVAL;
> -
> efi_runtime_map_copy(efi_map, efi_map_sz);
>
> ei->efi_memmap = efi_map_phys_addr & 0xffffffff;
> ei->efi_memmap_hi = efi_map_phys_addr >> 32;
> ei->efi_memmap_size = efi_map_sz;
> -
> - return 0;
> }
>
> -static int
> +static void
> prepare_add_efi_setup_data(struct boot_params *params,
> - unsigned long params_load_addr,
> - unsigned int efi_setup_data_offset)
> + unsigned long params_load_addr,
> + unsigned int params_cmdline_sz,
> + unsigned int efi_map_sz)
> {
> + unsigned int data_offset = params_cmdline_sz + ALIGN(efi_map_sz, 16);
> unsigned long setup_data_phys;
> - struct setup_data *sd = (void *)params + efi_setup_data_offset;
> + struct setup_data *sd = (void *)params + data_offset;
> struct efi_setup_data *esd = (void *)sd + sizeof(struct setup_data);
>
> esd->fw_vendor = efi.fw_vendor;
> @@ -152,33 +149,20 @@ prepare_add_efi_setup_data(struct boot_p
> sd->len = sizeof(struct efi_setup_data);
>
> /* Add setup data */
> - setup_data_phys = params_load_addr + efi_setup_data_offset;
> + setup_data_phys = params_load_addr + data_offset;
> sd->next = params->hdr.setup_data;
> params->hdr.setup_data = setup_data_phys;
> -
> - return 0;
> }
>
> static int
> setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
> - unsigned int efi_map_offset, unsigned int efi_map_sz,
> - unsigned int efi_setup_data_offset)
> + unsigned int params_cmdline_sz, unsigned int efi_map_sz)
> {
> struct efi_info *current_ei = &boot_params.efi_info;
> struct efi_info *ei = &params->efi_info;
> - int ret;
> -
> - if (!current_ei->efi_memmap_size)
> - return -EINVAL;
>
> - /*
> - * If 1:1 mapping is not enabled, second kernel can not setup EFI
> - * and use EFI run time services. User space will have to pass
> - * acpi_rsdp=<addr> on kernel command line to make second kernel boot
> - * without efi.
> - */
> - if (efi_enabled(EFI_OLD_MEMMAP) || !efi_enabled(EFI_RUNTIME_SERVICES))
> - return -ENODEV;
> + if (!efi_map_sz || !current_ei->efi_memmap_size)
> + return efi_map_sz ? -EINVAL : 0;
>
> ei->efi_loader_signature = current_ei->efi_loader_signature;
> ei->efi_systab = current_ei->efi_systab;
> @@ -187,21 +171,24 @@ setup_efi_state(struct boot_params *para
> ei->efi_memdesc_version = current_ei->efi_memdesc_version;
> ei->efi_memdesc_size = efi_get_runtime_map_desc_size();
>
> - ret = setup_efi_info_memmap(params, params_load_addr, efi_map_offset,
> + setup_efi_info_memmap(params, params_load_addr, params_cmdline_sz,
> efi_map_sz);
> - if (ret)
> - return ret;
> - prepare_add_efi_setup_data(params, params_load_addr,
> - efi_setup_data_offset);
> + prepare_add_efi_setup_data(params, params_load_addr, params_cmdline_sz,
> + efi_map_sz);
> return 0;
> }
> -#endif /* CONFIG_EFI */
> +#else /* !CONFIG_EFI_RUNTIME_MAP */
> +static int
> +setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
> + unsigned int params_cmdline_sz, unsigned int efi_map_sz)
> +{ return 0; }
> +#endif /* CONFIG_EFI_RUNTIME_MAP */
>
> static int
> setup_boot_parameters(struct kimage *image, struct boot_params *params,
> unsigned long params_load_addr,
> - unsigned int efi_map_offset, unsigned int efi_map_sz,
> - unsigned int efi_setup_data_offset)
> + unsigned int params_cmdline_sz,
> + unsigned int efi_map_sz)
> {
> unsigned int nr_e820_entries;
> unsigned long long mem_k, start, end;
> @@ -251,13 +238,9 @@ setup_boot_parameters(struct kimage *ima
> }
> }
>
> -#ifdef CONFIG_EFI
> - /* Setup EFI state */
> - ret = setup_efi_state(params, params_load_addr, efi_map_offset, efi_map_sz,
> - efi_setup_data_offset);
> - if (efi_enabled(EFI_BOOT) && ret)
> + ret = setup_efi_state(params, params_load_addr, params_cmdline_sz, efi_map_sz);
> + if (ret)
> return ret;
> -#endif
>
> /* Setup EDD info */
> memcpy(params->eddbuf, boot_params.eddbuf,
> @@ -343,7 +326,7 @@ static void *bzImage64_load(struct kimag
> struct kexec_entry64_regs regs64;
> void *stack;
> unsigned int setup_hdr_offset = offsetof(struct boot_params, hdr);
> - unsigned int efi_map_offset, efi_map_sz, efi_setup_data_offset;
> + unsigned int efi_map_sz = 0;
> struct kexec_buf kbuf = { .image = image, .buf_max = ULONG_MAX,
> .top_down = true };
> struct kexec_buf pbuf = { .image = image, .buf_min = MIN_PURGATORY_ADDR,
> @@ -402,19 +385,28 @@ static void *bzImage64_load(struct kimag
> * have to create separate segment for each. Keeps things
> * little bit simple
> */
> - efi_map_sz = efi_get_runtime_map_size();
> params_cmdline_sz = sizeof(struct boot_params) + cmdline_len +
> MAX_ELFCOREHDR_STR_LEN;
> params_cmdline_sz = ALIGN(params_cmdline_sz, 16);
> - kbuf.bufsz = params_cmdline_sz + ALIGN(efi_map_sz, 16) +
> - sizeof(struct setup_data) +
> - sizeof(struct efi_setup_data);
> + kbuf.bufsz = params_cmdline_sz + sizeof(struct setup_data);
> +
> + /*
> + * If a 1:1 mapping does not exist, the second kernel cannot setup
> + * and use EFI run time services, user space will have to pass
> + * acpi_rsdp=<addr> on the kernel command line to make the second
> + * kernel boot without efi. Allocate space for efi setup data if
> + * this constraint is met, bail if not, but is required to boot,
> + * and acpi_rsdp=<addr> was not passed on the command line.
> + */
> + if (efi_enabled(EFI_RUNTIME_SERVICES) && !efi_enabled(EFI_OLD_MEMMAP)) {
> + efi_map_sz = efi_get_runtime_map_size();
> + kbuf.bufsz += ALIGN(efi_map_sz, 16) + sizeof(struct efi_setup_data);
> + } else if (efi_enabled(EFI_BOOT) && !strstr(cmdline, "acpi_rsdp="))
> + return ERR_PTR(-ENODEV);
>
> params = kzalloc(kbuf.bufsz, GFP_KERNEL);
> if (!params)
> return ERR_PTR(-ENOMEM);
> - efi_map_offset = params_cmdline_sz;
> - efi_setup_data_offset = efi_map_offset + ALIGN(efi_map_sz, 16);
>
> /* Copy setup header onto bootparams. Documentation/x86/boot.txt */
> setup_header_size = 0x0202 + kernel[0x0201] - setup_hdr_offset;
> @@ -494,8 +486,7 @@ static void *bzImage64_load(struct kimag
> goto out_free_params;
>
> ret = setup_boot_parameters(image, params, bootparam_load_addr,
> - efi_map_offset, efi_map_sz,
> - efi_setup_data_offset);
> + params_cmdline_sz, efi_map_sz);
> if (ret)
> goto out_free_params;
>
>

Thanks
Dave

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