tests: prefer dynamically allocated buffers

Help detecting Valgrind OOB reads and other issues.

 Conditional jump or move depends on uninitialised value(s)
   at 0x5452886: blobmsg_parse (blobmsg.c:203)
   by 0x400A8E: test_blobmsg (tests/test-blobmsg-parse.c:66)
   by 0x400A8E: main (tests/test-blobmsg-parse.c:82)

 Conditional jump or move depends on uninitialised value(s)
   at 0x545247F: blobmsg_check_name (blobmsg.c:39)
   by 0x545247F: blobmsg_check_attr_len (blobmsg.c:79)
   by 0x5452710: blobmsg_parse_array (blobmsg.c:159)
   by 0x400AB8: test_blobmsg (tests/test-blobmsg-parse.c:69)
   by 0x400AB8: main (tests/test-blobmsg-parse.c:82)

 Conditional jump or move depends on uninitialised value(s)
   at 0x54524A0: blobmsg_check_name (blobmsg.c:42)
   by 0x54524A0: blobmsg_check_attr_len (blobmsg.c:79)
   by 0x5452710: blobmsg_parse_array (blobmsg.c:159)
   by 0x400AB8: test_blobmsg (tests/test-blobmsg-parse.c:69)
   by 0x400AB8: main (tests/test-blobmsg-parse.c:82)

Ref: http://lists.infradead.org/pipermail/openwrt-devel/2020-January/021204.html
Signed-off-by: Petr Štetiar <ynezz@true.cz>

1 files changed, 13 insertions, 4 deletions

diff --git a/tests/test-blob-parse.c b/tests/test-blob-parse.c
index 6d65eb4..5f58201 100644
--- a/tests/test-blob-parse.c
+++ b/tests/test-blob-parse.c
@@ -68,7 +68,7 @@ static int cert_load(const char *certfile, struct list_head *chain)
 	struct blob_attr *certtb[CERT_ATTR_MAX];
 	struct blob_attr *bufpt;
 	struct cert_object *cobj;
-	char filebuf[CERT_BUF_LEN];
+	char *filebuf = NULL;
 	int ret = 0, pret = 0;
 	size_t len, pos = 0;
 
@@ -76,14 +76,22 @@ static int cert_load(const char *certfile, struct list_head *chain)
 	if (!f)
 		return 1;
 
-	len = fread(&filebuf, 1, CERT_BUF_LEN - 1, f);
-	if (len < 64)
+	filebuf = malloc(CERT_BUF_LEN+1);
+	if (!filebuf)
 		return 1;
 
+	len = fread(filebuf, 1, CERT_BUF_LEN, f);
+	if (len < 64) {
+		free(filebuf);
+		return 1;
+	}
+
 	ret = ferror(f) || !feof(f);
 	fclose(f);
-	if (ret)
+	if (ret) {
+		free(filebuf);
 		return 1;
+	}
 
 	bufpt = (struct blob_attr *)filebuf;
 	do {
@@ -112,6 +120,7 @@ static int cert_load(const char *certfile, struct list_head *chain)
 	/* repeat parsing while there is still enough remaining data in buffer */
 	} while(len > pos + sizeof(struct blob_attr) && (bufpt = blob_next(bufpt)));
 
+	free(filebuf);
 	return (ret <= 0);
 }