[PATCH RH grub2] arm64: Fix EFI loader kernel image allocation
Benjamin Herrenschmidt
benh at kernel.crashing.org
Mon Jul 26 12:34:37 BST 2021
On Mon, 2021-07-26 at 11:44 +0200, Ard Biesheuvel wrote:
> On Mon, 26 Jul 2021 at 10:21, Benjamin Herrenschmidt
> <benh at kernel.crashing.org> wrote:
> > We are currently allocating just enough memory for the file size,
> > which means that the kernel BSS is in limbo (and not even zeroed).
> >
> > Instead, use the PE optional header in which the kernel puts the
> > actual size it needs, including BSS, and make sure we clear it.
> >
> > Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> > ---
> >
> > This bug comes with the original shim_lock patch which removes
> > LoadImage/StartImage
> > and directly calls into the loaded image instead. It has been
> > observbed to
> > occasionally cause boot failures on EC2 ARM instances.
> >
> > I know at least Fedora/RH (and thus Amazon Linux 2) and Ubuntu are
> > affected.
> >
>
> Thanks for fixing this. Does GRUB at least honor the minimum image
> alignment described in the PE/COFF header?
>
> Acked-by: Ard Biesheuvel <ardb at kernel.org>
It doesn't look at it no. So you'll get 4k.
Cheers,
Ben.
> > grub-core/loader/arm64/linux.c | 82 ++++++++++++++++++++++------
> > ------
> > 1 file changed, 54 insertions(+), 28 deletions(-)
> >
> > diff --git a/grub-core/loader/arm64/linux.c b/grub-
> > core/loader/arm64/linux.c
> > index 47f8cf0d8..f568d452d 100644
> > --- a/grub-core/loader/arm64/linux.c
> > +++ b/grub-core/loader/arm64/linux.c
> > @@ -311,14 +311,31 @@ grub_cmd_initrd (grub_command_t cmd
> > __attribute__ ((unused)),
> > return grub_errno;
> > }
> >
> > +static grub_err_t
> > +parse_pe_header (void *kernel, grub_uint64_t *total_size,
> > grub_uint32_t *entry_offset)
> > +{
> > + struct linux_arch_kernel_header *lh = kernel;
> > + struct grub_armxx_linux_pe_header *pe;
> > +
> > + pe = (void *)((unsigned long)kernel + lh->hdr_offset);
> > +
> > + if (pe->opt.magic != GRUB_PE32_PE64_MAGIC)
> > + return grub_error(GRUB_ERR_BAD_OS, "Invalid PE optional header
> > magic");
> > +
> > + *total_size = pe->opt.image_size;
> > + *entry_offset = pe->opt.entry_addr;
> > +
> > + return GRUB_ERR_NONE;
> > +}
> > +
> > static grub_err_t
> > grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
> > int argc, char *argv[])
> > {
> > grub_file_t file = 0;
> > - struct linux_arch_kernel_header lh;
> > - struct grub_armxx_linux_pe_header *pe;
> > grub_err_t err;
> > + grub_uint64_t filelen;
> > + void *kernel = NULL;
> > int rc;
> >
> > grub_dl_ref (my_mod);
> > @@ -333,40 +350,24 @@ grub_cmd_linux (grub_command_t cmd
> > __attribute__ ((unused)),
> > if (!file)
> > goto fail;
> >
> > - kernel_size = grub_file_size (file);
> > -
> > - if (grub_file_read (file, &lh, sizeof (lh)) < (long) sizeof
> > (lh))
> > - return grub_errno;
> > -
> > - if (grub_arch_efi_linux_check_image (&lh) != GRUB_ERR_NONE)
> > - goto fail;
> > -
> > - grub_loader_unset();
> > -
> > - grub_dprintf ("linux", "kernel file size: %lld\n", (long long)
> > kernel_size);
> > - kernel_addr = grub_efi_allocate_any_pages
> > (GRUB_EFI_BYTES_TO_PAGES (kernel_size));
> > - grub_dprintf ("linux", "kernel numpages: %lld\n",
> > - (long long) GRUB_EFI_BYTES_TO_PAGES (kernel_size));
> > - if (!kernel_addr)
> > + filelen = grub_file_size (file);
> > + kernel = grub_malloc(filelen);
> > + if (!kernel)
> > {
> > - grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("out of memory"));
> > + grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("cannot allocate
> > kernel load buffer"));
> > goto fail;
> > }
> >
> > - grub_file_seek (file, 0);
> > - if (grub_file_read (file, kernel_addr, kernel_size)
> > - < (grub_int64_t) kernel_size)
> > + if (grub_file_read (file, kernel, filelen) < filelen)
> > {
> > - if (!grub_errno)
> > - grub_error (GRUB_ERR_BAD_OS, N_("premature end of file
> > %s"), argv[0]);
> > + grub_error (GRUB_ERR_FILE_READ_ERROR, N_("Can't read kernel
> > %s"),
> > + argv[0]);
> > goto fail;
> > }
> >
> > - grub_dprintf ("linux", "kernel @ %p\n", kernel_addr);
> > -
> > if (grub_efi_get_secureboot () ==
> > GRUB_EFI_SECUREBOOT_MODE_ENABLED)
> > {
> > - rc = grub_linuxefi_secure_validate (kernel_addr,
> > kernel_size);
> > + rc = grub_linuxefi_secure_validate (kernel, filelen);
> > if (rc <= 0)
> > {
> > grub_error (GRUB_ERR_INVALID_COMMAND,
> > @@ -375,8 +376,30 @@ grub_cmd_linux (grub_command_t cmd
> > __attribute__ ((unused)),
> > }
> > }
> >
> > - pe = (void *)((unsigned long)kernel_addr + lh.hdr_offset);
> > - handover_offset = pe->opt.entry_addr;
> > + if (grub_arch_efi_linux_check_image (kernel) != GRUB_ERR_NONE)
> > + goto fail;
> > + if (parse_pe_header (kernel, &kernel_size, &handover_offset) !=
> > GRUB_ERR_NONE)
> > + goto fail;
> > + grub_dprintf ("linux", "kernel mem size : %lld\n", (long
> > long) kernel_size);
> > + grub_dprintf ("linux", "kernel entry offset : %d\n",
> > handover_offset);
> > +
> > + grub_loader_unset();
> > +
> > + kernel_addr = grub_efi_allocate_any_pages
> > (GRUB_EFI_BYTES_TO_PAGES (kernel_size));
> > + grub_dprintf ("linux", "kernel numpages: %lld\n",
> > + (long long) GRUB_EFI_BYTES_TO_PAGES (kernel_size));
> > + if (!kernel_addr)
> > + {
> > + grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("out of memory"));
> > + goto fail;
> > + }
> > +
> > + grub_dprintf ("linux", "kernel @ %p\n", kernel_addr);
> > + grub_memcpy (kernel_addr, kernel, grub_min(filelen,
> > kernel_size));
> > + if (kernel_size > filelen)
> > + grub_memset ((char *)kernel_addr + filelen, 0, kernel_size -
> > filelen);
> > + grub_free(kernel);
> > + kernel = NULL;
> >
> > cmdline_size = grub_loader_cmdline_size (argc, argv) + sizeof
> > (LINUX_IMAGE);
> > linux_args = grub_malloc (cmdline_size);
> > @@ -400,6 +423,9 @@ grub_cmd_linux (grub_command_t cmd
> > __attribute__ ((unused)),
> > }
> >
> > fail:
> > + if (kernel)
> > + grub_free (kernel);
> > +
> > if (file)
> > grub_file_close (file);
> >
> >
> >
> >
> > _______________________________________________
> > Efi mailing list
> > Efi at lists.einval.com
> > https://lists.einval.com/cgi-bin/mailman/listinfo/efi
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