[U-Boot] [PATCH v2 2/3] efi_loader: device_path: lift the upper limit in dp-to-text conversion

[AKASHI Takahiro]

There is no practical reason to set a maxmum length of text either for
file path or whole device path in device path-to-text conversion.

Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
---
 lib/efi_loader/efi_device_path_to_text.c | 90 +++++++++++++++++++++---
 1 file changed, 80 insertions(+), 10 deletions(-)

diff --git a/lib/efi_loader/efi_device_path_to_text.c b/lib/efi_loader/efi_device_path_to_text.c
index b158641e3043..75aabe66bf77 100644
--- a/lib/efi_loader/efi_device_path_to_text.c
+++ b/lib/efi_loader/efi_device_path_to_text.c
@@ -7,12 +7,12 @@
 
 #include <common.h>
 #include <efi_loader.h>
+#include <malloc.h>
 
 #define MAC_OUTPUT_LEN 22
 #define UNKNOWN_OUTPUT_LEN 23
 
 #define MAX_NODE_LEN 512
-#define MAX_PATH_LEN 1024
 
 const efi_guid_t efi_guid_device_path_to_text_protocol =
 		EFI_DEVICE_PATH_TO_TEXT_PROTOCOL_GUID;
@@ -228,8 +228,7 @@ static char *dp_media(char *s, struct efi_device_path *dp)
 		struct efi_device_path_file_path *fp =
 			(struct efi_device_path_file_path *)dp;
 		int slen = (dp->length - sizeof(*dp)) / 2;
-		if (slen > MAX_NODE_LEN - 2)
-			slen = MAX_NODE_LEN - 2;
+
 		s += sprintf(s, "%-.*ls", slen, fp->str);
 		break;
 	}
@@ -240,6 +239,31 @@ static char *dp_media(char *s, struct efi_device_path *dp)
 	return s;
 }
 
+/*
+ * Return a maximum size of buffer to be allocated for conversion
+ *
+ * @dp			device path or node
+ * @return		maximum size of buffer
+ */
+static size_t efi_dp_text_max(struct efi_device_path *dp)
+{
+	/*
+	 * We don't have be very accurate here.
+	 * Currently, there are only two cases where a maximum size
+	 * of buffer may go over MAX_NODE_LEN.
+	 */
+	if (dp->type == DEVICE_PATH_TYPE_HARDWARE_DEVICE &&
+	    dp->sub_type == DEVICE_PATH_SUB_TYPE_VENDOR)
+		/* VenHw(<guid>, xxxxxxxx...) */
+		return 8 + 36 + (dp->length - sizeof(*dp)) * 2 + 1;
+
+	if (dp->type == DEVICE_PATH_TYPE_MEDIA_DEVICE &&
+	    dp->sub_type == DEVICE_PATH_SUB_TYPE_FILE_PATH)
+		return dp->length - sizeof(*dp) + 2 /* u16 NULL */;
+
+	return MAX_NODE_LEN;
+}
+
 /*
  * Converts a single node to a char string.
  *
@@ -293,16 +317,27 @@ static uint16_t EFIAPI *efi_convert_device_node_to_text(
 		bool display_only,
 		bool allow_shortcuts)
 {
-	char str[MAX_NODE_LEN];
+	char *str;
+	size_t str_size;
 	uint16_t *text = NULL;
 
 	EFI_ENTRY("%p, %d, %d", device_node, display_only, allow_shortcuts);
 
 	if (!device_node)
 		goto out;
+
+	str_size = efi_dp_text_max(device_node);
+	if (!str_size)
+		goto out;
+
+	str = malloc(str_size);
+	if (!str)
+		goto out;
+
 	efi_convert_single_device_node_to_text(str, device_node);
 
 	text = efi_str_to_u16(str);
+	free(str);
 
 out:
 	EFI_EXIT(EFI_SUCCESS);
@@ -327,24 +362,59 @@ static uint16_t EFIAPI *efi_convert_device_path_to_text(
 		bool allow_shortcuts)
 {
 	uint16_t *text = NULL;
-	char buffer[MAX_PATH_LEN];
-	char *str = buffer;
+	char *buffer = NULL, *str;
+	size_t buf_size, buf_left;
+	efi_status_t ret = EFI_SUCCESS;
 
 	EFI_ENTRY("%p, %d, %d", device_path, display_only, allow_shortcuts);
 
-	if (!device_path)
+	if (!device_path) {
+		ret = EFI_INVALID_PARAMETER;
 		goto out;
-	while (device_path &&
-	       str + MAX_NODE_LEN < buffer + MAX_PATH_LEN) {
+	}
+
+	buf_size = 1024;
+	buf_left = buf_size;
+	buffer = malloc(buf_size);
+	if (!buffer) {
+		ret = EFI_OUT_OF_RESOURCES;
+		goto out;
+	}
+
+	str = buffer;
+	while (device_path) {
+		char *buf_new;
+		size_t buf_new_size, dp_text_len;
+
 		*str++ = '/';
+		buf_left--;
+		dp_text_len = efi_dp_text_max(device_path);
+		if (buf_left < dp_text_len) {
+			buf_new_size = buf_size + dp_text_len;
+			buf_new = malloc(buf_new_size);
+			if (!buf_new) {
+				ret = EFI_OUT_OF_RESOURCES;
+				goto out;
+			}
+
+			memcpy(buf_new, buffer, str - buffer);
+			buf_left = buf_new_size - (str - buffer);
+			str = buf_new + (str - buffer);
+			free(buffer);
+			buffer = buf_new;
+		}
+
 		str = efi_convert_single_device_node_to_text(str, device_path);
+
 		device_path = efi_dp_next(device_path);
 	}
 
 	text = efi_str_to_u16(buffer);
 
 out:
-	EFI_EXIT(EFI_SUCCESS);
+	free(buffer);
+	EFI_EXIT(ret);
+
 	return text;
 }
 
-- 
2.21.0