Add a new generic fuzz target for the QEMU VNC server. This target exercises both the standard VNC protocol and the VNC-over-WebSocket transport layer, increasing coverage of a primary remote attack surface.
To support parallel fuzzing (e.g., with oss-fuzz), the VNC unix socket paths are generated dynamically. The fuzzer harness inspects the command line for placeholders and replaces them with unique paths created by mkstemp() before execution. --- This new target increases code coverage in the VNC subsystem and related networking and I/O code. The baseline coverage below was generated by running all existing fuzz targets with the oss-fuzz corpus. The new target shows significant gains: ---------------------------------------------------------------------------- File New Target Baseline Change ---------------------------------------------------------------------------- vnc.c 339/3212 (10.6%) 3/3212 (0.1%) +336 keymaps.c 91/184 (49.5%) 0/184 (0.0%) +91 net-listener.c 76/198 (38.4%) 3/198 (1.5%) +73 channel-socket.c 73/575 (12.7%) 19/575 (3.3%) +54 qemu-sockets.c 44/1019 (4.3%) 0/1019 (0.0%) +44 vnc-jobs.c 41/219 (18.7%) 0/219 (0.0%) +41 dns-resolver.c 28/145 (19.3%) 3/145 (2.1%) +25 Signed-off-by: Navid Emamdoost <[email protected]> --- tests/qtest/fuzz/generic_fuzz_configs.h | 50 +++++++++++++++++++++++++ 1 file changed, 50 insertions(+) diff --git a/tests/qtest/fuzz/generic_fuzz_configs.h b/tests/qtest/fuzz/generic_fuzz_configs.h index ef0ad95712..9c46e106a4 100644 --- a/tests/qtest/fuzz/generic_fuzz_configs.h +++ b/tests/qtest/fuzz/generic_fuzz_configs.h @@ -29,6 +29,52 @@ static inline gchar *generic_fuzzer_virtio_9p_args(void){ "writeout=immediate,fmode=0600,dmode=0700", tmpdir); } +/* + * Global variables and cleanup handler for VNC fuzzer sockets. + * These are needed because the socket paths must be available at exit. + */ +static char g_vnc_socket_path[sizeof("/tmp/qemu-vnc.XXXXXX")]; +static char g_vnc_ws_socket_path[sizeof("/tmp/qemu-vnc-ws.XXXXXX")]; + +static void cleanup_vnc_sockets(void) +{ + if (g_vnc_socket_path[0] != '\0') { + unlink(g_vnc_socket_path); + } + if (g_vnc_ws_socket_path[0] != '\0') { + unlink(g_vnc_ws_socket_path); + } +} + +/* + * Dynamically generate VNC arguments with unique unix socket paths. + * This allows multiple fuzzing jobs to run in parallel without conflict. + */ +static inline gchar *generic_fuzzer_vnc_args(void) +{ + static bool cleanup_registered = false; + int fd; + + strcpy(g_vnc_socket_path, "/tmp/qemu-vnc.XXXXXX"); + fd = g_mkstemp(g_vnc_socket_path); + g_assert_cmpint(fd, !=, -1); + close(fd); + + strcpy(g_vnc_ws_socket_path, "/tmp/qemu-vnc-ws.XXXXXX"); + fd = g_mkstemp(g_vnc_ws_socket_path); + g_assert_cmpint(fd, !=, -1); + close(fd); + + if (!cleanup_registered) { + atexit(cleanup_vnc_sockets); + cleanup_registered = true; + } + + return g_strdup_printf("-machine q35 -nodefaults " + "-vnc vnc=unix:%s,websocket=unix:%s", + g_vnc_socket_path, g_vnc_ws_socket_path); +} + const generic_fuzz_config predefined_configs[] = { { .name = "virtio-net-pci-slirp", @@ -247,6 +293,10 @@ const generic_fuzz_config predefined_configs[] = { .args = "-machine q35 -nodefaults " "-parallel file:/dev/null", .objects = "parallel*", + },{ + .name = "vnc", + .argfunc = generic_fuzzer_vnc_args, + .objects = "*", } }; -- 2.51.2.1041.gc1ab5b90ca-goog
