Re: [PATCH net v2] sctp: fix memory leak in sctp_stream_outq_migrate()

[Xin Long <lucien.xin@xxxxxxxxx>]

On Thu, Nov 24, 2022 at 12:26 PM Marcelo Ricardo Leitner
<marcelo.leitner@xxxxxxxxx> wrote:
>
> On Thu, Nov 24, 2022 at 09:11:00PM +0800, Zhengchao Shao wrote:
> > When sctp_stream_outq_migrate() is called to release stream out resources,
> > the memory pointed to by prio_head in stream out is not released.
> >
> > The memory leak information is as follows:
> >  unreferenced object 0xffff88801fe79f80 (size 64):
> >    comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s)
> >    hex dump (first 32 bytes):
> >      80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff  ................
> >      90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff  ................
> >    backtrace:
> >      [<ffffffff81b215c6>] kmalloc_trace+0x26/0x60
> >      [<ffffffff88ae517c>] sctp_sched_prio_set+0x4cc/0x770
> >      [<ffffffff88ad64f2>] sctp_stream_init_ext+0xd2/0x1b0
> >      [<ffffffff88aa2604>] sctp_sendmsg_to_asoc+0x1614/0x1a30
> >      [<ffffffff88ab7ff1>] sctp_sendmsg+0xda1/0x1ef0
> >      [<ffffffff87f765ed>] inet_sendmsg+0x9d/0xe0
> >      [<ffffffff8754b5b3>] sock_sendmsg+0xd3/0x120
> >      [<ffffffff8755446a>] __sys_sendto+0x23a/0x340
> >      [<ffffffff87554651>] __x64_sys_sendto+0xe1/0x1b0
> >      [<ffffffff89978b49>] do_syscall_64+0x39/0xb0
> >      [<ffffffff89a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
> >
> > Link: https://syzkaller.appspot.com/bug?exrid=29c402e56c4760763cc0
> > Fixes: Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler")
> > Signed-off-by: Zhengchao Shao <shaozhengchao@xxxxxxxxxx>
> > ---
> > v2: add .free_sid hook function and use it to free a stream
>
> It's missing the change to sctp_stream_free as well. Please lets try
> to avoid having multiple paths freeing it differently as much as
> possible.
>
Right, something like:

@@ -181,9 +181,9 @@ void sctp_stream_free(struct sctp_stream *stream)
        struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream);
        int i;

-       sched->free(stream);
+       sched->unsched_all(stream)
        for (i = 0; i < stream->outcnt; i++)
-               kfree(SCTP_SO(stream, i)->ext);
+               sctp_stream_free_ext(stream, i);
        genradix_free(&stream->out);
        genradix_free(&stream->in);
 }

Thanks.