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 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@xxxxxx>
---
I CC'd the pstore people and linux-hardening mailing list because
get_maintainer.pl suggested to do so. Apologies in case this was the
incorrect decision, this is a very non-pstore-specific patch after all.
I have taken the liberty of adding a TODO for the future, the actual
refactor can follow at some point down the line.
---
drivers/firmware/efi/efi-pstore.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
index e7b9ec6f8a86..f0ceb5702d21 100644
--- a/drivers/firmware/efi/efi-pstore.c
+++ b/drivers/firmware/efi/efi-pstore.c
@@ -135,7 +135,15 @@ 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,
--
2.44.0
