commit 0fa95308fe5fcce8842530fcae5a49188856e6ac Author: Tobias Stoeckmann <tobias@stoeckmann.org> Date: Sun Mar 31 17:33:11 2019 +0200 Check return value of buf_move_to_buf for error. If the concatenation of connection buffer and the buffer of linked connection exceeds INT_MAX bytes, then buf_move_to_buf returns -1 as an error value. This value is currently casted to size_t (variable n_read) and will erroneously lead to an increasement of variable "max_to_read". This in turn can be used to call connection_buf_read_from_socket to store more data inside the buffer than expected and clogging the connection buffer. If the linked connection buffer was able to overflow INT_MAX, the call of buf_move_to_buf would have previously internally triggered an integer overflow, corrupting the state of the connection buffer. Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org> --- src/or/connection.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/src/or/connection.c b/src/or/connection.c index 791fd95c2..4f636eeb8 100644 --- a/src/or/connection.c +++ b/src/or/connection.c @@ -3581,6 +3581,10 @@ connection_read_to_buf(connection_t *conn, ssize_t *max_to_read, if (conn->linked_conn) { result = move_buf_to_buf(conn->inbuf, conn->linked_conn->outbuf, &conn->linked_conn->outbuf_flushlen); + if (BUG(result<0)) { + log_warn(LD_BUG, "reading from linked connection buffer failed."); + return -1; + } } else { result = 0; }