From a14f7152ce1c25cf110d3ccf640f9d4ce17dacd3 Mon Sep 17 00:00:00 2001 From: Daniel Stenberg Date: Fri, 8 Sep 2017 10:20:36 +0200 Subject: rtsp: do not call fwrite() with NULL pointer FILE * If the default write callback is used and no destination has been set, a NULL pointer would be passed to fwrite()'s 4th argument. OSS-fuzz bug https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=3327 (not publicly open yet) Detected by OSS-fuzz Closes #1874 --- lib/rtsp.c | 9 +++++++++ tests/fuzz/curl_fuzz_data/oss-fuzz-3327 | Bin 0 -> 27 bytes 2 files changed, 9 insertions(+) create mode 100644 tests/fuzz/curl_fuzz_data/oss-fuzz-3327 diff --git a/lib/rtsp.c b/lib/rtsp.c index 9bd935fd5..4bca11459 100644 --- a/lib/rtsp.c +++ b/lib/rtsp.c @@ -756,6 +756,15 @@ CURLcode rtp_client_write(struct connectdata *conn, char *ptr, size_t len) } writeit = data->set.fwrite_rtp?data->set.fwrite_rtp:data->set.fwrite_func; + + if(!data->set.fwrite_rtp && !data->set.is_fwrite_set && + !data->set.rtp_out) { + /* if no callback is set for either RTP or default, the default function + fwrite() is utilized and that can't handle a NULL input */ + failf(data, "No destination to default data callback!"); + return CURLE_WRITE_ERROR; + } + wrote = writeit(ptr, 1, len, data->set.rtp_out); if(CURL_WRITEFUNC_PAUSE == wrote) { diff --git a/tests/fuzz/curl_fuzz_data/oss-fuzz-3327 b/tests/fuzz/curl_fuzz_data/oss-fuzz-3327 new file mode 100644 index 000000000..064cc623a Binary files /dev/null and b/tests/fuzz/curl_fuzz_data/oss-fuzz-3327 differ -- cgit v1.2.1