From: Marcelo Ricardo Leitner marcelo.leitner@gmail.com
[ Upstream commit 4d1415811e492d9a8238f8a92dd0d51612c788e9 ]
It allocates the extended area for outbound streams only on sendmsg calls, if they are not yet allocated. When using the priority stream scheduler, this initialization may imply into a subsequent allocation, which may fail. In this case, it was aborting the stream scheduler initialization but leaving the ->ext pointer (allocated) in there, thus in a partially initialized state. On a subsequent call to sendmsg, it would notice the ->ext pointer in there, and trip on uninitialized stuff when trying to schedule the data chunk.
The fix is undo the ->ext initialization if the stream scheduler initialization fails and avoid the partially initialized state.
Although syzkaller bisected this to commit 4ff40b86262b ("sctp: set chunk transport correctly when it's a new asoc"), this bug was actually introduced on the commit I marked below.
Reported-by: syzbot+c1a380d42b190ad1e559@syzkaller.appspotmail.com Fixes: 5bbbbe32a431 ("sctp: introduce stream scheduler foundations") Tested-by: Xin Long lucien.xin@gmail.com Signed-off-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Acked-by: Neil Horman nhorman@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sctp/stream.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/net/sctp/stream.c +++ b/net/sctp/stream.c @@ -153,13 +153,20 @@ out: int sctp_stream_init_ext(struct sctp_stream *stream, __u16 sid) { struct sctp_stream_out_ext *soute; + int ret;
soute = kzalloc(sizeof(*soute), GFP_KERNEL); if (!soute) return -ENOMEM; SCTP_SO(stream, sid)->ext = soute;
- return sctp_sched_init_sid(stream, sid, GFP_KERNEL); + ret = sctp_sched_init_sid(stream, sid, GFP_KERNEL); + if (ret) { + kfree(SCTP_SO(stream, sid)->ext); + SCTP_SO(stream, sid)->ext = NULL; + } + + return ret; }
void sctp_stream_free(struct sctp_stream *stream)