commit dddd333a80ee2e9bb731cb3c127ace3741d49673 Author: Nick Mathewson <nickm@torproject.org> Date: Fri Mar 25 16:45:25 2011 -0400 Fix some 'impossible' overflow bugs in byte counting The first was genuinely impossible, I think: it could only happen when the amount we read differed from the amount we wanted to read by more than INT_MAX. The second is just very unlikely: it would give incorrect results to the controller if you somehow wrote or read more than 4GB on one edge conn in one second. That one is a bugfix on 0.1.2.8-beta. --- changes/count_overflow | 5 +++++ src/or/connection.c | 36 ++++++++++++++++++++++-------------- 2 files changed, 27 insertions(+), 14 deletions(-) diff --git a/changes/count_overflow b/changes/count_overflow new file mode 100644 index 0000000..f302ff2 --- /dev/null +++ b/changes/count_overflow @@ -0,0 +1,5 @@ + o Minor bugfixes: + - Correctly handle an "impossible" overflow cases in connection + byte counting, where we write or read more than 4GB on an edge + connection in single second. Bugfix on 0.1.2.8-beta. + diff --git a/src/or/connection.c b/src/or/connection.c index 7fa6cd9..084237d 100644 --- a/src/or/connection.c +++ b/src/or/connection.c @@ -51,7 +51,7 @@ static int connection_finished_flushing(connection_t *conn); static int connection_flushed_some(connection_t *conn); static int connection_finished_connecting(connection_t *conn); static int connection_reached_eof(connection_t *conn); -static int connection_read_to_buf(connection_t *conn, int *max_to_read, +static int connection_read_to_buf(connection_t *conn, ssize_t *max_to_read, int *socket_error); static int connection_process_inbuf(connection_t *conn, int package_partial); static void client_check_address_changed(int sock); @@ -2338,7 +2338,7 @@ connection_bucket_should_increase(int bucket, or_connection_t *conn) static int connection_handle_read_impl(connection_t *conn) { - int max_to_read=-1, try_to_read; + ssize_t max_to_read=-1, try_to_read; size_t before, n_read = 0; int socket_error = 0; @@ -2456,7 +2456,8 @@ connection_handle_read(connection_t *conn) * Return -1 if we want to break conn, else return 0. */ static int -connection_read_to_buf(connection_t *conn, int *max_to_read, int *socket_error) +connection_read_to_buf(connection_t *conn, ssize_t *max_to_read, + int *socket_error) { int result; ssize_t at_most = *max_to_read; @@ -2574,15 +2575,19 @@ connection_read_to_buf(connection_t *conn, int *max_to_read, int *socket_error) n_read = (size_t) result; } - if (n_read > 0) { /* change *max_to_read */ - /*XXXX022 check for overflow*/ - *max_to_read = (int)(at_most - n_read); - } + if (n_read > 0) { + /* change *max_to_read */ + *max_to_read = at_most - n_read; - if (conn->type == CONN_TYPE_AP) { - edge_connection_t *edge_conn = TO_EDGE_CONN(conn); - /*XXXX022 check for overflow*/ - edge_conn->n_read += (int)n_read; + /* Update edge_conn->n_read */ + if (conn->type == CONN_TYPE_AP) { + edge_connection_t *edge_conn = TO_EDGE_CONN(conn); + /* Check for overflow: */ + if (PREDICT_LIKELY(UINT32_MAX - edge_conn->n_read > n_read)) + edge_conn->n_read += (int)n_read; + else + edge_conn->n_read = UINT32_MAX; + } } connection_buckets_decrement(conn, approx_time(), n_read, n_written); @@ -2781,10 +2786,13 @@ connection_handle_write_impl(connection_t *conn, int force) n_written = (size_t) result; } - if (conn->type == CONN_TYPE_AP) { + if (n_written && conn->type == CONN_TYPE_AP) { edge_connection_t *edge_conn = TO_EDGE_CONN(conn); - /*XXXX022 check for overflow.*/ - edge_conn->n_written += (int)n_written; + /* Check for overflow: */ + if (PREDICT_LIKELY(UINT32_MAX - edge_conn->n_written > n_written)) + edge_conn->n_written += n_written; + else + edge_conn->n_written = UINT32_MAX; } connection_buckets_decrement(conn, approx_time(), n_read, n_written);