5.4-stable patches

added patches:
	efivarfs-request-at-most-512-bytes-for-variable-names.patch

2 files changed, 77 insertions, 0 deletions

diff --git a/queue-5.4/efivarfs-request-at-most-512-bytes-for-variable-names.patch b/queue-5.4/efivarfs-request-at-most-512-bytes-for-variable-names.patch
new file mode 100644
index 0000000000..e802cf54a3
--- /dev/null
+++ b/queue-5.4/efivarfs-request-at-most-512-bytes-for-variable-names.patch
@@ -0,0 +1,76 @@
+From f45812cc23fb74bef62d4eb8a69fe7218f4b9f2a Mon Sep 17 00:00:00 2001
+From: Tim Schumacher <timschumi@gmx.de>
+Date: Fri, 26 Jan 2024 17:25:23 +0100
+Subject: efivarfs: Request at most 512 bytes for variable names
+
+From: Tim Schumacher <timschumi@gmx.de>
+
+commit f45812cc23fb74bef62d4eb8a69fe7218f4b9f2a upstream.
+
+Work around a quirk in a few old (2011-ish) UEFI implementations, where
+a call to `GetNextVariableName` with a buffer size larger than 512 bytes
+will always return EFI_INVALID_PARAMETER.
+
+There is some lore around EFI variable names being up to 1024 bytes in
+size, but this has no basis in the UEFI specification, and the upper
+bounds are typically platform specific, and apply to the entire variable
+(name plus payload).
+
+Given that Linux does not permit creating files with names longer than
+NAME_MAX (255) bytes, 512 bytes (== 256 UTF-16 characters) is a
+reasonable limit.
+
+Cc: <stable@vger.kernel.org> # 6.1+
+Signed-off-by: Tim Schumacher <timschumi@gmx.de>
+Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
+[timschumi@gmx.de: adjusted diff for changed context and code move]
+Signed-off-by: Tim Schumacher <timschumi@gmx.de>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/firmware/efi/vars.c |   17 +++++++++++------
+ 1 file changed, 11 insertions(+), 6 deletions(-)
+
+--- a/drivers/firmware/efi/vars.c
++++ b/drivers/firmware/efi/vars.c
+@@ -427,7 +427,7 @@ int efivar_init(int (*func)(efi_char16_t
+ 		void *data, bool duplicates, struct list_head *head)
+ {
+ 	const struct efivar_operations *ops;
+-	unsigned long variable_name_size = 1024;
++	unsigned long variable_name_size = 512;
+ 	efi_char16_t *variable_name;
+ 	efi_status_t status;
+ 	efi_guid_t vendor_guid;
+@@ -450,12 +450,13 @@ int efivar_init(int (*func)(efi_char16_t
+ 	}
+ 
+ 	/*
+-	 * Per EFI spec, the maximum storage allocated for both
+-	 * the variable name and variable data is 1024 bytes.
++	 * A small set of old UEFI implementations reject sizes
++	 * above a certain threshold, the lowest seen in the wild
++	 * is 512.
+ 	 */
+ 
+ 	do {
+-		variable_name_size = 1024;
++		variable_name_size = 512;
+ 
+ 		status = ops->get_next_variable(&variable_name_size,
+ 						variable_name,
+@@ -499,9 +500,13 @@ int efivar_init(int (*func)(efi_char16_t
+ 			break;
+ 		case EFI_NOT_FOUND:
+ 			break;
++		case EFI_BUFFER_TOO_SMALL:
++			pr_warn("efivars: Variable name size exceeds maximum (%lu > 512)\n",
++				variable_name_size);
++			status = EFI_NOT_FOUND;
++			break;
+ 		default:
+-			printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
+-				status);
++			pr_warn("efivars: get_next_variable: status=%lx\n", status);
+ 			status = EFI_NOT_FOUND;
+ 			break;
+ 		}
diff --git a/queue-5.4/series b/queue-5.4/series
index 2d6e004da5..24bcd76be7 100644
--- a/queue-5.4/series
+++ b/queue-5.4/series
@@ -104,3 +104,4 @@ loop-factor-out-configuring-loop-from-status.patch
 loop-check-for-overflow-while-configuring-loop.patch
 loop-loop_set_status_from_info-check-before-assignment.patch
 perf-core-fix-reentry-problem-in-perf_output_read_group.patch
+efivarfs-request-at-most-512-bytes-for-variable-names.patch