[PATCH] efi_loader: loosen buffer parameter check in efi_file_read_int

[Peng Fan (OSS)]

From: Peng Fan <peng.fan at nxp.com>

This is same issue as https://bugzilla.redhat.com/show_bug.cgi?id=1733817,
but that fix was wrongly partial reverted.

To Fedora shim loader, when buffer is NULL, a use-case is to call
efi_file_read with *buffer_size=0 and buffer=NULL to obtain the needed
size before doing the actual read.

Otherwise, we always met "Could not read \EFI\: Invalid Parameter"

Fixes: db12f518edb0("efi_loader: implement non-blocking file services")
Signed-off-by: Peng Fan <peng.fan at nxp.com>
Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
Cc: Stefan Sørensen <stefan.sorensen at spectralink.com>
---
 lib/efi_loader/efi_file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/efi_loader/efi_file.c b/lib/efi_loader/efi_file.c
index 204105e25a..6b3f5962be 100644
--- a/lib/efi_loader/efi_file.c
+++ b/lib/efi_loader/efi_file.c
@@ -554,7 +554,7 @@ static efi_status_t efi_file_read_int(struct efi_file_handle *this,
 	efi_status_t ret = EFI_SUCCESS;
 	u64 bs;
 
-	if (!this || !buffer_size || !buffer)
+	if (!this || !buffer_size)
 		return EFI_INVALID_PARAMETER;
 
 	bs = *buffer_size;
-- 
2.30.0