chore(mysql): create regression test for RUSTSEC-2024-0363

Cargo.toml

@@ -328,6 +328,11 @@ name = "mysql-migrate"
 path = "tests/mysql/migrate.rs"
 required-features = ["mysql", "macros", "migrate"]
 
+[[test]]
+name = "mysql-rustsec"
+path = "tests/mysql/rustsec.rs"
+required-features = ["mysql"]
+
 #
 # PostgreSQL
 #

tests/mysql/rustsec.rs

@@ -0,0 +1,67 @@
+use sqlx::{Error, MySql};
+use std::io;
+
+use sqlx_test::new;
+
+// https://rustsec.org/advisories/RUSTSEC-2024-0363.html
+//
+// During the audit the MySQL driver was found to be *unlikely* to be vulnerable to the exploit,
+// so this just serves as a sanity check.
+#[sqlx::test]
+async fn rustsec_2024_0363() -> anyhow::Result<()> {
+    let overflow_len = 4 * 1024 * 1024 * 1024; // 4 GiB
+
+    let padding = " ".repeat(overflow_len);
+
+    let payload = "UPDATE injection_target SET message = 'you''ve been pwned!' WHERE id = 1";
+
+    let mut injected_value = String::with_capacity(overflow_len + payload.len());
+
+    injected_value.push_str(&padding);
+    injected_value.push_str(payload);
+
+    // Since this is so large, keeping it around until the end *can* lead to getting OOM-killed.
+    drop(padding);
+
+    let mut conn = new::<MySql>().await?;
+
+    sqlx::raw_sql(
+        "CREATE TEMPORARY TABLE injection_target(id INTEGER PRIMARY KEY AUTO_INCREMENT, message TEXT);\n\
+         INSERT INTO injection_target(message) VALUES ('existing message');",
+    )
+    .execute(&mut conn)
+    .await?;
+
+    // We can't concatenate a query string together like the other tests
+    // because it would just demonstrate a regular old SQL injection.
+    let res = sqlx::query("INSERT INTO injection_target(message) VALUES (?)")
+        .bind(&injected_value)
+        .execute(&mut conn)
+        .await;
+
+    if let Err(e) = res {
+        // Connection rejected the query; we're happy.
+        //
+        // Current observed behavior is that `mysqld` closes the connection before we're even done
+        // sending the message, giving us a "Broken pipe" error.
+        //
+        // As it turns out, MySQL has a tight limit on packet sizes (even after splitting)
+        // by default: https://dev.mysql.com/doc/refman/8.4/en/packet-too-large.html
+        if matches!(e, Error::Io(ref ioe) if ioe.kind() == io::ErrorKind::BrokenPipe) {
+            return Ok(());
+        }
+
+        panic!("unexpected error: {e:?}");
+    }
+
+    let messages: Vec<String> =
+        sqlx::query_scalar("SELECT message FROM injection_target ORDER BY id")
+            .fetch_all(&mut conn)
+            .await?;
+
+    assert_eq!(messages[0], "existing_message");
+    assert_eq!(messages[1].len(), injected_value.len());
+
+    // Injection didn't affect our database; we're happy.
+    Ok(())
+}