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EFI fixes for v6.10 #1

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- Followup fix for the EFI boot sequence refactor, which may result in
   physical KASLR putting the kernel in a region which is being used for
   a special purpose via a command line argument.
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Merge tag 'efi-fixes-for-v6.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi

Pull EFI fix from Ard Biesheuvel:

 - Followup fix for the EFI boot sequence refactor, which may result in
   physical KASLR putting the kernel in a region which is being used for
   a special purpose via a command line argument.

* tag 'efi-fixes-for-v6.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
  x86/efistub: Omit physical KASLR when memory reservations exist
This commit is contained in:
Linus Torvalds 2024-05-21 11:50:26 -07:00
commit 5499315668
1 changed files with 26 additions and 2 deletions
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28
drivers/firmware/efi/libstub/x86-stub.c
View File

@ -776,6 +776,26 @@ static void error(char *str)
efi_warn("Decompression failed: %s\n", str);
}
static const char *cmdline_memmap_override;
static efi_status_t parse_options(const char *cmdline)
{
static const char opts[][14] = {
"mem=", "memmap=", "efi_fake_mem=", "hugepages="
};
for (int i = 0; i < ARRAY_SIZE(opts); i++) {
const char *p = strstr(cmdline, opts[i]);
if (p == cmdline || (p > cmdline && isspace(p[-1]))) {
cmdline_memmap_override = opts[i];
break;
}
}
return efi_parse_options(cmdline);
}
static efi_status_t efi_decompress_kernel(unsigned long *kernel_entry)
{
unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
@ -807,6 +827,10 @@ static efi_status_t efi_decompress_kernel(unsigned long *kernel_entry)
!memcmp(efistub_fw_vendor(), ami, sizeof(ami))) {
efi_debug("AMI firmware v2.0 or older detected - disabling physical KASLR\n");
seed[0] = 0;
} else if (cmdline_memmap_override) {
efi_info("%s detected on the kernel command line - disabling physical KASLR\n",
cmdline_memmap_override);
seed[0] = 0;
}
boot_params_ptr->hdr.loadflags |= KASLR_FLAG;
@ -883,7 +907,7 @@ void __noreturn efi_stub_entry(efi_handle_t handle,
}
#ifdef CONFIG_CMDLINE_BOOL
status = efi_parse_options(CONFIG_CMDLINE);
status = parse_options(CONFIG_CMDLINE);
if (status != EFI_SUCCESS) {
efi_err("Failed to parse options\n");
goto fail;
@ -892,7 +916,7 @@ void __noreturn efi_stub_entry(efi_handle_t handle,
if (!IS_ENABLED(CONFIG_CMDLINE_OVERRIDE)) {
unsigned long cmdline_paddr = ((u64)hdr->cmd_line_ptr |
((u64)boot_params->ext_cmd_line_ptr << 32));
status = efi_parse_options((char *)cmdline_paddr);
status = parse_options((char *)cmdline_paddr);
if (status != EFI_SUCCESS) {
efi_err("Failed to parse options\n");
goto fail;