Re: [PATCH net v4] sctp: fix memory leak in sctp_stream_outq_migrate()

[Xin Long <lucien.xin@gmail.com>]

On Fri, Nov 25, 2022 at 10:11 PM Zhengchao Shao
<shaozhengchao@huawei.com> 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: 637784ade221 ("sctp: introduce priority based stream scheduler")
> Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com
> Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
> ---
> v4: use .free_sid to free a new stream
> v3: also add .free_sid for sctp_sched_fcfs/rr and make sure only free
>     once in sctp_stream_free()
> v2: add .free_sid hook function and use it to free a stream
> ---
>  include/net/sctp/stream_sched.h |  2 ++
>  net/sctp/stream.c               | 25 ++++++++++++++++++-------
>  net/sctp/stream_sched.c         |  5 +++++
>  net/sctp/stream_sched_prio.c    | 19 +++++++++++++++++++
>  net/sctp/stream_sched_rr.c      |  5 +++++
>  5 files changed, 49 insertions(+), 7 deletions(-)
>
> diff --git a/include/net/sctp/stream_sched.h b/include/net/sctp/stream_sched.h
> index 01a70b27e026..65058faea4db 100644
> --- a/include/net/sctp/stream_sched.h
> +++ b/include/net/sctp/stream_sched.h
> @@ -26,6 +26,8 @@ struct sctp_sched_ops {
>         int (*init)(struct sctp_stream *stream);
>         /* Init a stream */
>         int (*init_sid)(struct sctp_stream *stream, __u16 sid, gfp_t gfp);
> +       /* free a stream */
> +       void (*free_sid)(struct sctp_stream *stream, __u16 sid);
>         /* Frees the entire thing */
>         void (*free)(struct sctp_stream *stream);
>
> diff --git a/net/sctp/stream.c b/net/sctp/stream.c
> index ef9fceadef8d..ee6514af830f 100644
> --- a/net/sctp/stream.c
> +++ b/net/sctp/stream.c
> @@ -52,6 +52,19 @@ static void sctp_stream_shrink_out(struct sctp_stream *stream, __u16 outcnt)
>         }
>  }
>
> +static void sctp_stream_free_ext(struct sctp_stream *stream, __u16 sid)
> +{
> +       struct sctp_sched_ops *sched;
> +
> +       if (!SCTP_SO(stream, sid)->ext)
> +               return;
> +
> +       sched = sctp_sched_ops_from_stream(stream);
> +       sched->free_sid(stream, sid);
> +       kfree(SCTP_SO(stream, sid)->ext);
> +       SCTP_SO(stream, sid)->ext = NULL;
> +}
> +
>  /* Migrates chunks from stream queues to new stream queues if needed,
>   * but not across associations. Also, removes those chunks to streams
>   * higher than the new max.
> @@ -70,16 +83,14 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream,
>                  * sctp_stream_update will swap ->out pointers.
>                  */
>                 for (i = 0; i < outcnt; i++) {
> -                       kfree(SCTP_SO(new, i)->ext);
> +                       sctp_stream_free_ext(new, i);
>                         SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext;
>                         SCTP_SO(stream, i)->ext = NULL;
>                 }
>         }
>
> -       for (i = outcnt; i < stream->outcnt; i++) {
> -               kfree(SCTP_SO(stream, i)->ext);
> -               SCTP_SO(stream, i)->ext = NULL;
> -       }
> +       for (i = outcnt; i < stream->outcnt; i++)
> +               sctp_stream_free_ext(stream, i);
>  }
>
>  static int sctp_stream_alloc_out(struct sctp_stream *stream, __u16 outcnt,
> @@ -174,9 +185,9 @@ 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);
>  }
> diff --git a/net/sctp/stream_sched.c b/net/sctp/stream_sched.c
> index 1ad565ed5627..7c8f9d89e16a 100644
> --- a/net/sctp/stream_sched.c
> +++ b/net/sctp/stream_sched.c
> @@ -46,6 +46,10 @@ static int sctp_sched_fcfs_init_sid(struct sctp_stream *stream, __u16 sid,
>         return 0;
>  }
>
> +static void sctp_sched_fcfs_free_sid(struct sctp_stream *stream, __u16 sid)
> +{
> +}
> +
>  static void sctp_sched_fcfs_free(struct sctp_stream *stream)
>  {
>  }
> @@ -96,6 +100,7 @@ static struct sctp_sched_ops sctp_sched_fcfs = {
>         .get = sctp_sched_fcfs_get,
>         .init = sctp_sched_fcfs_init,
>         .init_sid = sctp_sched_fcfs_init_sid,
> +       .free_sid = sctp_sched_fcfs_free_sid,
>         .free = sctp_sched_fcfs_free,
>         .enqueue = sctp_sched_fcfs_enqueue,
>         .dequeue = sctp_sched_fcfs_dequeue,
> diff --git a/net/sctp/stream_sched_prio.c b/net/sctp/stream_sched_prio.c
> index 80b5a2c4cbc7..4fc9f2923ed1 100644
> --- a/net/sctp/stream_sched_prio.c
> +++ b/net/sctp/stream_sched_prio.c
> @@ -204,6 +204,24 @@ static int sctp_sched_prio_init_sid(struct sctp_stream *stream, __u16 sid,
>         return sctp_sched_prio_set(stream, sid, 0, gfp);
>  }
>
> +static void sctp_sched_prio_free_sid(struct sctp_stream *stream, __u16 sid)
> +{
> +       struct sctp_stream_priorities *prio = SCTP_SO(stream, sid)->ext->prio_head;
> +       int i;
> +
> +       if (!prio)
> +               return;
> +
> +       SCTP_SO(stream, sid)->ext->prio_head = NULL;
> +       for (i = 0; i < stream->outcnt; i++) {
> +               if (SCTP_SO(stream, i)->ext &&
> +                   SCTP_SO(stream, i)->ext->prio_head == prio)
> +                       return;
> +       }
> +
> +       kfree(prio);
> +}
> +
>  static void sctp_sched_prio_free(struct sctp_stream *stream)
>  {
>         struct sctp_stream_priorities *prio, *n;
> @@ -323,6 +341,7 @@ static struct sctp_sched_ops sctp_sched_prio = {
>         .get = sctp_sched_prio_get,
>         .init = sctp_sched_prio_init,
>         .init_sid = sctp_sched_prio_init_sid,
> +       .free_sid = sctp_sched_prio_free_sid,
>         .free = sctp_sched_prio_free,
>         .enqueue = sctp_sched_prio_enqueue,
>         .dequeue = sctp_sched_prio_dequeue,
> diff --git a/net/sctp/stream_sched_rr.c b/net/sctp/stream_sched_rr.c
> index ff425aed62c7..cc444fe0d67c 100644
> --- a/net/sctp/stream_sched_rr.c
> +++ b/net/sctp/stream_sched_rr.c
> @@ -90,6 +90,10 @@ static int sctp_sched_rr_init_sid(struct sctp_stream *stream, __u16 sid,
>         return 0;
>  }
>
> +static void sctp_sched_rr_free_sid(struct sctp_stream *stream, __u16 sid)
> +{
> +}
> +
>  static void sctp_sched_rr_free(struct sctp_stream *stream)
>  {
>         sctp_sched_rr_unsched_all(stream);
> @@ -177,6 +181,7 @@ static struct sctp_sched_ops sctp_sched_rr = {
>         .get = sctp_sched_rr_get,
>         .init = sctp_sched_rr_init,
>         .init_sid = sctp_sched_rr_init_sid,
> +       .free_sid = sctp_sched_rr_free_sid,
>         .free = sctp_sched_rr_free,
>         .enqueue = sctp_sched_rr_enqueue,
>         .dequeue = sctp_sched_rr_dequeue,
> --
> 2.17.1
>

Thanks.

Reviewed-by: Xin Long <lucien.xin@gmail.com>