[OpenWrt-Devel] [PATCH fwtool 8/8] fix possible garbage in unitialized char* struct members

[Petr Štetiar]

scan-build from clang version 9 has reported following issues:

 crc32.h:44:32: warning: The right operand of '^' is a garbage value
                val = crc_table[(uint8_t)val ^ *(uint8_t*)buf] ^ (val >> 8);
                                             ^ ~~~~~~~~~~~~~~

cppcheck version 1.89 has reported following issues:

 fwtool.c:260:9: error: Uninitialized variable: dest [uninitvar]
  memcpy(dest, dbuf->cur + dbuf->cur_len - cur_len, cur_len);
         ^
 fwtool.c:333:27: note: Calling function 'extract_tail', 2nd argument '&tr' value is <Uninit>
   if (extract_tail(&dbuf, &tr, sizeof(tr))) {
                           ^

Signed-off-by: Petr Štetiar <ynezz at true.cz>
---
 fwtool.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/fwtool.c b/fwtool.c
index e925b0bf5e65..6340db9da63c 100644
--- a/fwtool.c
+++ b/fwtool.c
@@ -145,11 +145,12 @@ append_trailer(FILE *out, struct fwimage_trailer *tr)
 static int
 add_metadata(struct fwimage_trailer *tr)
 {
-	struct fwimage_header hdr = {};
+	struct fwimage_header hdr;
 
 	tr->type = FWIMAGE_INFO;
 	tr->size = sizeof(hdr) + sizeof(*tr);
 
+	memset(&hdr, 0, sizeof(hdr));
 	trailer_update_crc(tr, &hdr, sizeof(hdr));
 	fwrite(&hdr, sizeof(hdr), 1, firmware_file);
 
@@ -181,13 +182,15 @@ add_signature(struct fwimage_trailer *tr)
 static int
 add_data(const char *name)
 {
-	struct fwimage_trailer tr = {
-		.magic = cpu_to_be32(FWIMAGE_MAGIC),
-		.crc32 = ~0,
-	};
+	struct fwimage_trailer tr;
 	int file_len = 0;
 	int ret = 0;
 
+	memset(&tr, 0, sizeof(tr));
+
+	tr.crc32 = ~0;
+	tr.magic = cpu_to_be32(FWIMAGE_MAGIC);
+
 	firmware_file = fopen(name, "r+");
 	if (!firmware_file) {
 		msg("Failed to open firmware file\n");
@@ -289,6 +292,8 @@ extract_data(const char *name)
 	void *buf;
 	bool metadata_keep = false;
 
+	memset(&tr, 0, sizeof(tr));
+
 	firmware_file = open_file(name, false);
 	if (!firmware_file) {
 		msg("Failed to open firmware file\n");

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