From 24427cda90cbbb9015c73e2dd3329a116a00c8de Mon Sep 17 00:00:00 2001
From: Tim Schumacher <timschumi@gmx.de>
Date: Thu, 28 Mar 2024 21:50:30 +0100
Subject: [PATCH] efi: pstore: Request at most 512 bytes for variable names
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.
This was already done to efivarfs in commit f45812cc23fb ("efivarfs:
Request at most 512 bytes for variable names"), but the second copy of
the variable iteration implementation was overlooked.
Signed-off-by: Tim Schumacher <timschumi@gmx.de>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
drivers/firmware/efi/efi-pstore.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
index 833cbb995dd3f..5b9dc26e6bcb9 100644
--- a/drivers/firmware/efi/efi-pstore.c
+++ b/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,
--
2.30.2