EFI updates for v6.10:

- Additional cleanup by Tim for the efivarfs variable name length
   confusion
 
 - Avoid freeing a bogus pointer when virtual remapping is omitted in the
   EFI boot stub
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Merge tag 'efi-next-for-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi

Pull EFI updates from Ard Biesheuvel:
 "Only a handful of changes this cycle, consisting of cleanup work and a
  low-prio bugfix:

   - Additional cleanup by Tim for the efivarfs variable name length
     confusion

   - Avoid freeing a bogus pointer when virtual remapping is omitted in
     the EFI boot stub"

* tag 'efi-next-for-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
  efi: libstub: only free priv.runtime_map when allocated
  efi: Clear up misconceptions about a maximum variable name size
  efivarfs: Remove unused internal struct members
  Documentation: Mark the 'efivars' sysfs interface as removed
  efi: pstore: Request at most 512 bytes for variable names

Documentation/ABI/removed/sysfs-firmware-efi-vars

@@ -0,0 +1,12 @@
+What:		/sys/firmware/efi/vars
+Date:		April 2004, removed March 2023
+Description:
+		This directory exposed interfaces for interacting with
+		EFI variables.  For more information on EFI variables,
+		see 'Variable Services' in the UEFI specification
+		(section 7.2 in specification version 2.3 Errata D).
+
+		The 'efivars' sysfs interface was removed in March of 2023,
+		after being considered deprecated no later than September
+		of 2020. Its functionality has been replaced by the
+		'efivarfs' filesystem.

Documentation/ABI/stable/sysfs-firmware-efi-vars

@@ -1,79 +0,0 @@
-What:		/sys/firmware/efi/vars
-Date:		April 2004
-Contact:	Matt Domsch <Matt_Domsch@dell.com>
-Description:
-		This directory exposes interfaces for interactive with
-		EFI variables.  For more information on EFI variables,
-		see 'Variable Services' in the UEFI specification
-		(section 7.2 in specification version 2.3 Errata D).
-
-		In summary, EFI variables are named, and are classified
-		into separate namespaces through the use of a vendor
-		GUID.  They also have an arbitrary binary value
-		associated with them.
-
-		The efivars module enumerates these variables and
-		creates a separate directory for each one found.  Each
-		directory has a name of the form "<key>-<vendor guid>"
-		and contains the following files:
-
-		=============== ========================================
-		attributes:	A read-only text file enumerating the
-				EFI variable flags.  Potential values
-				include:
-
-				EFI_VARIABLE_NON_VOLATILE
-				EFI_VARIABLE_BOOTSERVICE_ACCESS
-				EFI_VARIABLE_RUNTIME_ACCESS
-				EFI_VARIABLE_HARDWARE_ERROR_RECORD
-				EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS
-
-				See the EFI documentation for an
-				explanation of each of these variables.
-
-		data:		A read-only binary file that can be read
-				to attain the value of the EFI variable
-
-		guid:		The vendor GUID of the variable.  This
-				should always match the GUID in the
-				variable's name.
-
-		raw_var:	A binary file that can be read to obtain
-				a structure that contains everything
-				there is to know about the variable.
-				For structure definition see "struct
-				efi_variable" in the kernel sources.
-
-				This file can also be written to in
-				order to update the value of a variable.
-				For this to work however, all fields of
-				the "struct efi_variable" passed must
-				match byte for byte with the structure
-				read out of the file, save for the value
-				portion.
-
-				**Note** the efi_variable structure
-				read/written with this file contains a
-				'long' type that may change widths
-				depending on your underlying
-				architecture.
-
-		size:		As ASCII representation of the size of
-				the variable's value.
-		=============== ========================================
-
-
-		In addition, two other magic binary files are provided
-		in the top-level directory and are used for adding and
-		removing variables:
-
-		=============== ========================================
-		new_var:	Takes a "struct efi_variable" and
-				instructs the EFI firmware to create a
-				new variable.
-
-		del_var:	Takes a "struct efi_variable" and
-				instructs the EFI firmware to remove any
-				variable that has a matching vendor GUID
-				and variable key name.
-		=============== ========================================

Documentation/filesystems/efivarfs.rst

@@ -40,4 +40,4 @@ accidentally.
 *See also:*
 
 - Documentation/admin-guide/acpi/ssdt-overlays.rst
-- Documentation/ABI/stable/sysfs-firmware-efi-vars
+- Documentation/ABI/removed/sysfs-firmware-efi-vars

drivers/firmware/efi/efi-pstore.c

@@ -162,7 +162,15 @@ static ssize_t efi_pstore_read(struct pstore_record *record)
 	efi_status_t status;
 
 	for (;;) {
-		varname_size = 1024;
+		/*
+		 * A small set of old UEFI implementations reject sizes
+		 * above a certain threshold, the lowest seen in the wild
+		 * is 512.
+		 *
+		 * TODO: Commonize with the iteration implementation in
+		 *       fs/efivarfs to keep all the quirks in one place.
+		 */
+		varname_size = 512;
 
 		/*
 		 * If this is the first read() call in the pstore enumeration,

drivers/firmware/efi/libstub/fdt.c

@@ -335,7 +335,7 @@ fail_free_new_fdt:
 
 fail:
 	efi_free(fdt_size, fdt_addr);
-
+	if (!efi_novamap)
 		efi_bs_call(free_pool, priv.runtime_map);
 
 	return EFI_LOAD_ERROR;

drivers/firmware/efi/vars.c

@@ -215,7 +215,7 @@ efi_status_t efivar_set_variable_locked(efi_char16_t *name, efi_guid_t *vendor,
 
 	if (data_size > 0) {
 		status = check_var_size(nonblocking, attr,
-					data_size + ucs2_strsize(name, 1024));
+					data_size + ucs2_strsize(name, EFI_VAR_NAME_LEN));
 		if (status != EFI_SUCCESS)
 			return status;
 	}

fs/efivarfs/internal.h

@@ -24,11 +24,8 @@ struct efivarfs_fs_info {
 struct efi_variable {
 	efi_char16_t  VariableName[EFI_VAR_NAME_LEN/sizeof(efi_char16_t)];
 	efi_guid_t    VendorGuid;
-	unsigned long DataSize;
-	__u8          Data[1024];
-	efi_status_t  Status;
 	__u32         Attributes;
-} __attribute__((packed));
+};
 
 struct efivar_entry {
 	struct efi_variable var;

fs/efivarfs/vars.c

@@ -295,9 +295,9 @@ static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor,
 	unsigned long strsize1, strsize2;
 	bool found = false;
 
-	strsize1 = ucs2_strsize(variable_name, 1024);
+	strsize1 = ucs2_strsize(variable_name, EFI_VAR_NAME_LEN);
 	list_for_each_entry_safe(entry, n, head, list) {
-		strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
+		strsize2 = ucs2_strsize(entry->var.VariableName, EFI_VAR_NAME_LEN);
 		if (strsize1 == strsize2 &&
 			!memcmp(variable_name, &(entry->var.VariableName),
 				strsize2) &&
@@ -396,6 +396,7 @@ int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *,
 
 	do {
 		variable_name_size = 512;
+		BUILD_BUG_ON(EFI_VAR_NAME_LEN < 512);
 
 		status = efivar_get_next_variable(&variable_name_size,
 						  variable_name,

include/linux/efi.h

@@ -1072,12 +1072,11 @@ static inline u64 efivar_reserved_space(void) { return 0; }
 #endif
 
 /*
- * The maximum size of VariableName + Data = 1024
- * Therefore, it's reasonable to save that much
- * space in each part of the structure,
- * and we use a page for reading/writing.
+ * There is no actual upper limit specified for the variable name size.
+ *
+ * This limit exists only for practical purposes, since name conversions
+ * are bounds-checked and name data is occasionally stored in-line.
  */
-
 #define EFI_VAR_NAME_LEN	1024
 
 int efivars_register(struct efivars *efivars,