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

1 files changed, 26 insertions, 2 deletions

diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
index d5a8182cf2e1..1983fd3bf392 100644
--- a/drivers/firmware/efi/libstub/x86-stub.c
+++ b/drivers/firmware/efi/libstub/x86-stub.c
@@ -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;