[PATCH 1/2] efi: loader: don't let VarToFile stop the variable file from being written

[Ahmad Fatoum]

efi_var_collect() walks the variable store with GetNextVariableName() and
reads every variable it finds into a buffer the size of the store, then
keeps only those matching the attribute mask. Reading a variable whose
value does not fit aborts the collection, and with it the write of the
variable file:

  efi-loader: var-file: Failed to persist EFI variables Out of memory

VarToFile is such a variable. Its value is not stored anywhere: reading
it serializes all non-volatile variables, so it needed as much room as
everything collected before it.

Assisted-by: Claude:opus-5
Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 efi/loader/efi_var_common.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/efi/loader/efi_var_common.c b/efi/loader/efi_var_common.c
index 4c6cb77e7c2c..dcdfa6fb0165 100644
--- a/efi/loader/efi_var_common.c
+++ b/efi/loader/efi_var_common.c
@@ -454,6 +454,14 @@ efi_status_t __maybe_unused efi_var_collect(struct efi_var_file **bufp, loff_t *
 		ret = efi_get_variable_int(var->name, &var->guid,
 					   &var->attr, &data_length, data,
 					   &var->time);
+		/*
+		 * The attributes are valid even when the value did not fit.
+		 * Variables we are not going to keep may thus be skipped
+		 * without their value ever being copied, e.g. VarToFile.
+		 */
+		if (ret == EFI_BUFFER_TOO_SMALL &&
+		    (var->attr & check_attr_mask) != check_attr_mask)
+			continue;
 		if (ret != EFI_SUCCESS) {
 			free(buf);
 			return ret;
-- 
2.47.3