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Date: Sat, 26 Nov 2022 10:05:35 +0800
From: shaozhengchao <shaozhengchao@...wei.com>
To: Xin Long <lucien.xin@...il.com>
CC: <netdev@...r.kernel.org>, <linux-sctp@...r.kernel.org>,
<vyasevich@...il.com>, <nhorman@...driver.com>,
<marcelo.leitner@...il.com>, <davem@...emloft.net>,
<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
<syzkaller-bugs@...glegroups.com>, <weiyongjun1@...wei.com>,
<yuehaibing@...wei.com>
Subject: Re: [PATCH net v3] sctp: fix memory leak in
sctp_stream_outq_migrate()
On 2022/11/26 0:34, Xin Long wrote:
> ,
>
> On Thu, Nov 24, 2022 at 9:59 PM Zhengchao Shao <shaozhengchao@...wei.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: Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler")
>> Reported-by: syzbot+29c402e56c4760763cc0@...kaller.appspotmail.com
>> Signed-off-by: Zhengchao Shao <shaozhengchao@...wei.com>
>> ---
>> 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 | 21 +++++++++++++++------
>> net/sctp/stream_sched.c | 5 +++++
>> net/sctp/stream_sched_prio.c | 19 +++++++++++++++++++
>> net/sctp/stream_sched_rr.c | 5 +++++
>> 5 files changed, 46 insertions(+), 6 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..30bf9ba10f8e 100644
>> --- a/net/sctp/stream.c
>> +++ b/net/sctp/stream.c
>> @@ -52,6 +52,17 @@ 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 = sctp_sched_ops_from_stream(stream);
>> +
>> + if (SCTP_SO(stream, sid)->ext) {
>> + sched->free_sid(stream, sid);
>> + kfree(SCTP_SO(stream, sid)->ext);
>> + SCTP_SO(stream, sid)->ext = NULL;
>> + }
>> +}
>> +
> 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;
> }
>
> This will look better to me.
>
>> /* 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.
>> @@ -76,10 +87,8 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream,
>> }
>> }
>>
>> - 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);
>> }
> 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;
> }
>
> We should replace this one too so that all ext frees go to the same function.
>
> That's all from me.
>
> Thanks.
>
Hi Long:
Thank you for your review. I will send V4.
Zhengchao Shao
>>
>> static int sctp_stream_alloc_out(struct sctp_stream *stream, __u16 outcnt,
>> @@ -174,9 +183,9 @@ 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
>>
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