[ulogd2 PATCH v2 20/27] output: SQLITE3: Fix string truncation warnings and possible buffer overruns

[Jeremy Sowden <jeremy@xxxxxxxxxx>]

Extend name length to match input key.

Replace strncpy with snprintf.

Remove superfluous intermediate buffers.

Leave `field->name` with underscores: we can get the key-name from
`field->key->name`.

Signed-off-by: Jeremy Sowden <jeremy@xxxxxxxxxx>
---
 output/sqlite3/ulogd_output_SQLITE3.c | 38 +++++++++++----------------
 1 file changed, 16 insertions(+), 22 deletions(-)

diff --git a/output/sqlite3/ulogd_output_SQLITE3.c b/output/sqlite3/ulogd_output_SQLITE3.c
index 20ceb3b5d6e2..053d7a3b0238 100644
--- a/output/sqlite3/ulogd_output_SQLITE3.c
+++ b/output/sqlite3/ulogd_output_SQLITE3.c
@@ -48,7 +48,7 @@
 
 struct field {
 	TAILQ_ENTRY(field) link;
-	char name[ULOGD_MAX_KEYLEN];
+	char name[ULOGD_MAX_KEYLEN + 1];
 	struct ulogd_key *key;
 };
 
@@ -214,8 +214,6 @@ sqlite3_createstmt(struct ulogd_pluginstance *pi)
 {
 	struct sqlite3_priv *priv = (void *)pi->private;
 	struct field *f;
-	char buf[ULOGD_MAX_KEYLEN];
-	char *underscore;
 	char *stmt_pos;
 	int i, cols = 0;
 
@@ -231,12 +229,7 @@ sqlite3_createstmt(struct ulogd_pluginstance *pi)
 	stmt_pos = priv->stmt + strlen(priv->stmt);
 
 	tailq_for_each(f, priv->fields, link) {
-		strncpy(buf, f->name, ULOGD_MAX_KEYLEN);
-
-		while ((underscore = strchr(buf, '.')))
-			*underscore = '_';
-
-		sprintf(stmt_pos, "%s,", buf);
+		sprintf(stmt_pos, "%s,", f->name);
 		stmt_pos = priv->stmt + strlen(priv->stmt);
 
 		cols++;
@@ -273,10 +266,15 @@ sqlite3_createstmt(struct ulogd_pluginstance *pi)
 static struct ulogd_key *
 ulogd_find_key(struct ulogd_pluginstance *pi, const char *name)
 {
+	char key_name[ULOGD_MAX_KEYLEN + 1] = "";
 	unsigned int i;
 
+	/* replace all underscores with dots */
+	for (i = 0; i < sizeof(key_name) && name[i]; ++i)
+		key_name[i] = name[i] != '_' ? name[i] : '.';
+
 	for (i = 0; i < pi->input.num_keys; i++) {
-		if (strcmp(pi->input.keys[i].name, name) == 0)
+		if (strcmp(pi->input.keys[i].name, key_name) == 0)
 			return &pi->input.keys[i];
 	}
 
@@ -305,9 +303,6 @@ static int
 sqlite3_init_db(struct ulogd_pluginstance *pi)
 {
 	struct sqlite3_priv *priv = (void *)pi->private;
-	char buf[ULOGD_MAX_KEYLEN];
-	char *underscore;
-	struct field *f;
 	sqlite3_stmt *schema_stmt;
 	int col, num_cols;
 
@@ -327,23 +322,22 @@ sqlite3_init_db(struct ulogd_pluginstance *pi)
 	}
 
 	for (col = 0; col < num_cols; col++) {
-		strncpy(buf, sqlite3_column_name(schema_stmt, col), ULOGD_MAX_KEYLEN);
-
-		/* replace all underscores with dots */
-		while ((underscore = strchr(buf, '_')) != NULL)
-			*underscore = '.';
-
-		DEBUGP("field '%s' found\n", buf);
+		struct field *f;
 
 		/* prepend it to the linked list */
 		if ((f = calloc(1, sizeof(struct field))) == NULL) {
 			ulogd_log(ULOGD_ERROR, "SQLITE3: out of memory\n");
 			return -1;
 		}
-		strncpy(f->name, buf, ULOGD_MAX_KEYLEN);
+		snprintf(f->name, sizeof(f->name),
+			 "%s", sqlite3_column_name(schema_stmt, col));
 
-		if ((f->key = ulogd_find_key(pi, buf)) == NULL)
+		DEBUGP("field '%s' found\n", f->name);
+
+		if ((f->key = ulogd_find_key(pi, f->name)) == NULL) {
+			free(f);
 			return -1;
+		}
 
 		TAILQ_INSERT_TAIL(&priv->fields, f, link);
 	}
-- 
2.33.0