4.20-stable review patch. If anyone has any objections, please let me know.
------------------ From: Xin Long <[email protected]> [ Upstream commit af98c5a78517c04adb5fd68bb64b1ad6fe3d473f ] In sctp_stream_init(), after sctp_stream_outq_migrate() freed the surplus streams' ext, but sctp_stream_alloc_out() returns -ENOMEM, stream->outcnt will not be set to 'outcnt'. With the bigger value on stream->outcnt, when closing the assoc and freeing its streams, the ext of those surplus streams will be freed again since those stream exts were not set to NULL after freeing in sctp_stream_outq_migrate(). Then the invalid-free issue reported by syzbot would be triggered. We fix it by simply setting them to NULL after freeing. Fixes: 5bbbbe32a431 ("sctp: introduce stream scheduler foundations") Reported-by: [email protected] Signed-off-by: Xin Long <[email protected]> Acked-by: Neil Horman <[email protected]> Acked-by: Marcelo Ricardo Leitner <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- net/sctp/stream.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/net/sctp/stream.c +++ b/net/sctp/stream.c @@ -144,8 +144,10 @@ static void sctp_stream_outq_migrate(str } } - for (i = outcnt; i < stream->outcnt; i++) + for (i = outcnt; i < stream->outcnt; i++) { kfree(SCTP_SO(stream, i)->ext); + SCTP_SO(stream, i)->ext = NULL; + } } static int sctp_stream_alloc_out(struct sctp_stream *stream, __u16 outcnt,
