[PATCH] efi_loader: Fix a memory leak when retrieving device paths from boot vars

[Ilias Apalodimas]

get_dp_device() is used to derive the device path from a boot variable.
However, if the last efi_get_variable_int() call fails, we return an
error without freeing 'buf'.

There's no need to call efi_get_variable_int() for variables we don't
know the size since we have the efi_get_var() wrapper.

Replace that in the two instances we use it. The first one will also
fix the memory leak.
A nice sideeffect is that the code size is also reduced, since we are
re-using functions instead of open coding them

$~ bloat-o-meter u-boot u-boot.new
add/remove: 0/0 grow/shrink: 1/2 up/down: 6/-196 (-190)
Function                                     old     new   delta
version_string                                70      76      +6
efi_launch_capsules                         2288    2196     -92
get_dp_device                                244     140    -104
Total: Before=1222331, After=1222141, chg -0.02%

Fixes: c74cd8bd08d1 ("efi_loader: capsule: add capsule_on_disk support")
Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
---
 lib/efi_loader/efi_capsule.c | 34 +++++++---------------------------
 1 file changed, 7 insertions(+), 27 deletions(-)

diff --git a/lib/efi_loader/efi_capsule.c b/lib/efi_loader/efi_capsule.c
index 31b47a20186e..eafc647f558f 100644
--- a/lib/efi_loader/efi_capsule.c
+++ b/lib/efi_loader/efi_capsule.c
@@ -857,18 +857,9 @@ static efi_status_t get_dp_device(u16 *boot_var,
 	struct efi_device_path *file_dp;
 	efi_status_t ret;

-	size = 0;
-	ret = efi_get_variable_int(boot_var, &efi_global_variable_guid,
-				   NULL, &size, NULL, NULL);
-	if (ret == EFI_BUFFER_TOO_SMALL) {
-		buf = malloc(size);
-		if (!buf)
-			return EFI_OUT_OF_RESOURCES;
-		ret = efi_get_variable_int(boot_var, &efi_global_variable_guid,
-					   NULL, &size, buf, NULL);
-	}
-	if (ret != EFI_SUCCESS)
-		return ret;
+	buf = efi_get_var(boot_var, &efi_global_variable_guid, &size);
+	if (!buf)
+		return EFI_NOT_FOUND;

 	efi_deserialize_load_option(&lo, buf, &size);

@@ -960,22 +951,11 @@ static efi_status_t find_boot_device(void)

 skip:
 	/* find active boot device in BootOrder */
-	size = 0;
-	ret = efi_get_variable_int(u"BootOrder", &efi_global_variable_guid,
-				   NULL, &size, NULL, NULL);
-	if (ret == EFI_BUFFER_TOO_SMALL) {
-		boot_order = malloc(size);
-		if (!boot_order) {
-			ret = EFI_OUT_OF_RESOURCES;
-			goto out;
-		}
-
-		ret = efi_get_variable_int(u"BootOrder",
-					   &efi_global_variable_guid,
-					   NULL, &size, boot_order, NULL);
-	}
-	if (ret != EFI_SUCCESS)
+	boot_order = efi_get_var(u"BootOrder", &efi_global_variable_guid, &size);
+	if (!boot_order) {
+		ret = EFI_NOT_FOUND;
 		goto out;
+	}

 	/* check in higher order */
 	num = size / sizeof(u16);
--
2.43.0