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Date: Fri, 10 Aug 2018 18:28:46 +0800
From: Dave Young <dyoung@...hat.com>
To: Mike Galbraith <efault@....de>
Cc: Baoquan He <bhe@...hat.com>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86, kdump: Fix efi=noruntime NULL pointer dereference
On 08/10/18 at 04:45pm, Dave Young wrote:
> On 08/08/18 at 04:03pm, Mike Galbraith wrote:
> > When booting with efi=noruntime, we call efi_runtime_map_copy() while
> > loading the kdump kernel, and trip over a NULL efi.memmap.map. Avoid
> > that and a useless allocation when the only mapping we can use (1:1)
> > is not available.
> >
> > Signed-off-by: Mike Galbraith <efault@....de>
> > ---
> > arch/x86/kernel/kexec-bzimage64.c | 22 +++++++++++-----------
> > 1 file changed, 11 insertions(+), 11 deletions(-)
> >
> > --- a/arch/x86/kernel/kexec-bzimage64.c
> > +++ b/arch/x86/kernel/kexec-bzimage64.c
> > @@ -122,9 +122,6 @@ static int setup_efi_info_memmap(struct
> > unsigned long efi_map_phys_addr = params_load_addr + efi_map_offset;
> > struct efi_info *ei = ¶ms->efi_info;
> >
> > - if (!efi_map_sz)
> > - return 0;
> > -
> > efi_runtime_map_copy(efi_map, efi_map_sz);
> >
> > ei->efi_memmap = efi_map_phys_addr & 0xffffffff;
> > @@ -176,7 +173,7 @@ setup_efi_state(struct boot_params *para
> > * acpi_rsdp=<addr> on kernel command line to make second kernel boot
> > * without efi.
> > */
> > - if (efi_enabled(EFI_OLD_MEMMAP))
> > + if (efi_enabled(EFI_OLD_MEMMAP) || !efi_enabled(EFI_MEMMAP))
> > return 0;
> >
> > ei->efi_loader_signature = current_ei->efi_loader_signature;
> > @@ -338,7 +335,7 @@ 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_offset = 0, efi_map_sz = 0, efi_setup_data_offset = 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,
> > @@ -397,19 +394,22 @@ 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);
> > +
> > + /* Now add space for the efi stuff if we have a useable 1:1 mapping. */
> > + if (!efi_enabled(EFI_OLD_MEMMAP) && efi_enabled(EFI_MEMMAP)) {
> > + efi_map_sz = efi_get_runtime_map_size();
> > + kbuf.bufsz += ALIGN(efi_map_sz, 16) + sizeof(struct efi_setup_data);
> > + efi_map_offset = params_cmdline_sz;
> > + efi_setup_data_offset = efi_map_offset + ALIGN(efi_map_sz, 16);
> > + }
> >
> > 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;
>
> BTW, this patch only fix the kexec load phase problem, even if kexec
> load successfully with the fix, the 2nd kernel can not boot because efi
> memmap info is not correct and usable.
>
> So we should go with some fix similar to below, and do the cleanup we
> mentioned with a separate patch later.
>
> Also user space kexec-tools need a similar patch to error out in case
> no runtime maps. It would be good to fix both userspace and kernel
> load.
>
> diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
> index 7326078eaa7a..e34ba2f53cfb 100644
> --- a/arch/x86/kernel/kexec-bzimage64.c
> +++ b/arch/x86/kernel/kexec-bzimage64.c
> @@ -123,7 +123,7 @@ static int setup_efi_info_memmap(struct boot_params *params,
> struct efi_info *ei = ¶ms->efi_info;
>
> if (!efi_map_sz)
> - return 0;
> + return -EINVAL;
>
> efi_runtime_map_copy(efi_map, efi_map_sz);
>
> @@ -166,9 +166,10 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
> {
> struct efi_info *current_ei = &boot_params.efi_info;
> struct efi_info *ei = ¶ms->efi_info;
> + int ret;
>
> if (!current_ei->efi_memmap_size)
> - return 0;
> + return -EINVAL;
>
> /*
> * If 1:1 mapping is not enabled, second kernel can not setup EFI
> @@ -176,8 +177,8 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
> * acpi_rsdp=<addr> on kernel command line to make second kernel boot
> * without efi.
> */
> - if (efi_enabled(EFI_OLD_MEMMAP))
> - return 0;
> + if (efi_enabled(EFI_OLD_MEMMAP) || !efi_enabled(EFI_RUNTIME_SERVICES))
> + return -ENODEV;
>
> ei->efi_loader_signature = current_ei->efi_loader_signature;
> ei->efi_systab = current_ei->efi_systab;
> @@ -186,8 +187,10 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
> ei->efi_memdesc_version = current_ei->efi_memdesc_version;
> ei->efi_memdesc_size = efi_get_runtime_map_desc_size();
>
> - setup_efi_info_memmap(params, params_load_addr, efi_map_offset,
> + ret = setup_efi_info_memmap(params, params_load_addr, efi_map_offset,
> efi_map_sz);
> + if (ret)
> + return ret;
> prepare_add_efi_setup_data(params, params_load_addr,
> efi_setup_data_offset);
> return 0;
> @@ -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
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..
> + return ret;
> #endif
>
> /* Setup EDD info */
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