* [PATCH v2] net/smc: fix TCP fallback socket release
@ 2018-12-17 5:21 Myungho Jung
2018-12-17 14:58 ` Ursula Braun
0 siblings, 1 reply; 4+ messages in thread
From: Myungho Jung @ 2018-12-17 5:21 UTC (permalink / raw)
To: Ursula Braun, David S. Miller; +Cc: linux-s390, netdev, linux-kernel
clcsock can be released while kernel_accept() references it in TCP
listen worker. Also, clcsock needs to wake up before released if TCP
fallback is used and the clcsock is blocked by accept. Add a lock to
safely release clcsock and call kernel_sock_shutdown() to wake up
clcsock from accept in smc_release().
Reported-by: syzbot+0bf2e01269f1274b4b03@syzkaller.appspotmail.com
Reported-by: syzbot+e3132895630f957306bc@syzkaller.appspotmail.com
Signed-off-by: Myungho Jung <mhjungk@gmail.com>
---
net/smc/af_smc.c | 14 ++++++++++++--
net/smc/smc.h | 2 ++
2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 5fbaf1901571..5d06fb1bbccf 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -147,8 +147,14 @@ static int smc_release(struct socket *sock)
sk->sk_shutdown |= SHUTDOWN_MASK;
}
if (smc->clcsock) {
+ if (smc->use_fallback && sk->sk_state == SMC_LISTEN) {
+ /* wake up clcsock accept */
+ rc = kernel_sock_shutdown(smc->clcsock, SHUT_RDWR);
+ }
+ mutex_lock(&smc->clcsock_release_lock);
sock_release(smc->clcsock);
smc->clcsock = NULL;
+ mutex_unlock(&smc->clcsock_release_lock);
}
if (smc->use_fallback) {
if (sk->sk_state != SMC_LISTEN && sk->sk_state != SMC_INIT)
@@ -205,6 +211,7 @@ static struct sock *smc_sock_alloc(struct net *net, struct socket *sock,
spin_lock_init(&smc->conn.send_lock);
sk->sk_prot->hash(sk);
sk_refcnt_debug_inc(sk);
+ mutex_init(&smc->clcsock_release_lock);
return sk;
}
@@ -821,7 +828,7 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
struct socket *new_clcsock = NULL;
struct sock *lsk = &lsmc->sk;
struct sock *new_sk;
- int rc;
+ int rc = 0;
release_sock(lsk);
new_sk = smc_sock_alloc(sock_net(lsk), NULL, lsk->sk_protocol);
@@ -834,7 +841,10 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
}
*new_smc = smc_sk(new_sk);
- rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0);
+ mutex_lock(&lsmc->clcsock_release_lock);
+ if (lsmc->clcsock)
+ rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0);
+ mutex_unlock(&lsmc->clcsock_release_lock);
lock_sock(lsk);
if (rc < 0)
lsk->sk_err = -rc;
diff --git a/net/smc/smc.h b/net/smc/smc.h
index 08786ace6010..9a2795cf5d30 100644
--- a/net/smc/smc.h
+++ b/net/smc/smc.h
@@ -219,6 +219,8 @@ struct smc_sock { /* smc sock container */
* started, waiting for unsent
* data to be sent
*/
+ struct mutex clcsock_release_lock;
+ /* protects clcsock */
};
static inline struct smc_sock *smc_sk(const struct sock *sk)
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH v2] net/smc: fix TCP fallback socket release
2018-12-17 5:21 [PATCH v2] net/smc: fix TCP fallback socket release Myungho Jung
@ 2018-12-17 14:58 ` Ursula Braun
2018-12-18 7:03 ` Myungho Jung
0 siblings, 1 reply; 4+ messages in thread
From: Ursula Braun @ 2018-12-17 14:58 UTC (permalink / raw)
To: Myungho Jung; +Cc: David S. Miller, linux-s390, netdev, linux-kernel
On 12/17/2018 06:21 AM, Myungho Jung wrote:
> clcsock can be released while kernel_accept() references it in TCP
> listen worker. Also, clcsock needs to wake up before released if TCP
> fallback is used and the clcsock is blocked by accept. Add a lock to
> safely release clcsock and call kernel_sock_shutdown() to wake up
> clcsock from accept in smc_release().
Thanks for your effort to solve this problem. I have some minor
improvement proposals:
>
> Reported-by: syzbot+0bf2e01269f1274b4b03@syzkaller.appspotmail.com
> Reported-by: syzbot+e3132895630f957306bc@syzkaller.appspotmail.com
> Signed-off-by: Myungho Jung <mhjungk@gmail.com>
> ---
> net/smc/af_smc.c | 14 ++++++++++++--
> net/smc/smc.h | 2 ++
> 2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
> index 5fbaf1901571..5d06fb1bbccf 100644
> --- a/net/smc/af_smc.c
> +++ b/net/smc/af_smc.c
> @@ -147,8 +147,14 @@ static int smc_release(struct socket *sock)
> sk->sk_shutdown |= SHUTDOWN_MASK;
> }
> if (smc->clcsock) {
> + if (smc->use_fallback && sk->sk_state == SMC_LISTEN) {
> + /* wake up clcsock accept */
> + rc = kernel_sock_shutdown(smc->clcsock, SHUT_RDWR);
> + }
This part is not needed, since an SMC socket in state SMC_LISTEN is never
a use_fallback socket.
> + mutex_lock(&smc->clcsock_release_lock);
> sock_release(smc->clcsock);
> smc->clcsock = NULL;
> + mutex_unlock(&smc->clcsock_release_lock);
> }
> if (smc->use_fallback) {
> if (sk->sk_state != SMC_LISTEN && sk->sk_state != SMC_INIT)
> @@ -205,6 +211,7 @@ static struct sock *smc_sock_alloc(struct net *net, struct socket *sock,
> spin_lock_init(&smc->conn.send_lock);
> sk->sk_prot->hash(sk);
> sk_refcnt_debug_inc(sk);
> + mutex_init(&smc->clcsock_release_lock);
>
> return sk;
> }
> @@ -821,7 +828,7 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
> struct socket *new_clcsock = NULL;
> struct sock *lsk = &lsmc->sk;
> struct sock *new_sk;
> - int rc;
> + int rc = 0;
Without clcsock the good path should not be executed. Thus I suggest
to initialize with something negative like -EINVAL.
>
> release_sock(lsk);
> new_sk = smc_sock_alloc(sock_net(lsk), NULL, lsk->sk_protocol);
> @@ -834,7 +841,10 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
> }
> *new_smc = smc_sk(new_sk);
>
> - rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0);
> + mutex_lock(&lsmc->clcsock_release_lock);
> + if (lsmc->clcsock)
> + rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0);
> + mutex_unlock(&lsmc->clcsock_release_lock);
> lock_sock(lsk);
> if (rc < 0)
> lsk->sk_err = -rc;
> diff --git a/net/smc/smc.h b/net/smc/smc.h
> index 08786ace6010..9a2795cf5d30 100644
> --- a/net/smc/smc.h
> +++ b/net/smc/smc.h
> @@ -219,6 +219,8 @@ struct smc_sock { /* smc sock container */
> * started, waiting for unsent
> * data to be sent
> */
> + struct mutex clcsock_release_lock;
> + /* protects clcsock */
I suggest to be more precise: "protects clcsock of a listen socket"
> };
>
> static inline struct smc_sock *smc_sk(const struct sock *sk)
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH v2] net/smc: fix TCP fallback socket release
2018-12-17 14:58 ` Ursula Braun
@ 2018-12-18 7:03 ` Myungho Jung
2018-12-18 11:24 ` Ursula Braun
0 siblings, 1 reply; 4+ messages in thread
From: Myungho Jung @ 2018-12-18 7:03 UTC (permalink / raw)
To: Ursula Braun; +Cc: David S. Miller, linux-s390, netdev, linux-kernel
On Mon, Dec 17, 2018 at 03:58:58PM +0100, Ursula Braun wrote:
>
Hi Ursula,
Thank you for your suggestion. I have a question on your comment.
>
> On 12/17/2018 06:21 AM, Myungho Jung wrote:
> > clcsock can be released while kernel_accept() references it in TCP
> > listen worker. Also, clcsock needs to wake up before released if TCP
> > fallback is used and the clcsock is blocked by accept. Add a lock to
> > safely release clcsock and call kernel_sock_shutdown() to wake up
> > clcsock from accept in smc_release().
>
> Thanks for your effort to solve this problem. I have some minor
> improvement proposals:
>
> >
> > Reported-by: syzbot+0bf2e01269f1274b4b03@syzkaller.appspotmail.com
> > Reported-by: syzbot+e3132895630f957306bc@syzkaller.appspotmail.com
> > Signed-off-by: Myungho Jung <mhjungk@gmail.com>
> > ---
> > net/smc/af_smc.c | 14 ++++++++++++--
> > net/smc/smc.h | 2 ++
> > 2 files changed, 14 insertions(+), 2 deletions(-)
> >
> > diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
> > index 5fbaf1901571..5d06fb1bbccf 100644
> > --- a/net/smc/af_smc.c
> > +++ b/net/smc/af_smc.c
> > @@ -147,8 +147,14 @@ static int smc_release(struct socket *sock)
> > sk->sk_shutdown |= SHUTDOWN_MASK;
> > }
> > if (smc->clcsock) {
> > + if (smc->use_fallback && sk->sk_state == SMC_LISTEN) {
> > + /* wake up clcsock accept */
> > + rc = kernel_sock_shutdown(smc->clcsock, SHUT_RDWR);
> > + }
>
> This part is not needed, since an SMC socket in state SMC_LISTEN is never
> a use_fallback socket.
In smc_sendmsg(), set use_fallback to true if SMC socket is SMC_INIT
state and the message has MSG_FASTOPEN flag. After this, smc_listen()
would trigger smc_tcp_listen_work(). Is this not an expected scenario?
Then, what is the reason for not skipping smc_sendmsg() in SMC_INIT
state?
>
> > + mutex_lock(&smc->clcsock_release_lock);
> > sock_release(smc->clcsock);
> > smc->clcsock = NULL;
> > + mutex_unlock(&smc->clcsock_release_lock);
> > }
> > if (smc->use_fallback) {
> > if (sk->sk_state != SMC_LISTEN && sk->sk_state != SMC_INIT)
> > @@ -205,6 +211,7 @@ static struct sock *smc_sock_alloc(struct net *net, struct socket *sock,
> > spin_lock_init(&smc->conn.send_lock);
> > sk->sk_prot->hash(sk);
> > sk_refcnt_debug_inc(sk);
> > + mutex_init(&smc->clcsock_release_lock);
> >
> > return sk;
> > }
> > @@ -821,7 +828,7 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
> > struct socket *new_clcsock = NULL;
> > struct sock *lsk = &lsmc->sk;
> > struct sock *new_sk;
> > - int rc;
> > + int rc = 0;
>
> Without clcsock the good path should not be executed. Thus I suggest
> to initialize with something negative like -EINVAL.
>
> >
> > release_sock(lsk);
> > new_sk = smc_sock_alloc(sock_net(lsk), NULL, lsk->sk_protocol);
> > @@ -834,7 +841,10 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
> > }
> > *new_smc = smc_sk(new_sk);
> >
> > - rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0);
> > + mutex_lock(&lsmc->clcsock_release_lock);
> > + if (lsmc->clcsock)
> > + rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0);
> > + mutex_unlock(&lsmc->clcsock_release_lock);
> > lock_sock(lsk);
> > if (rc < 0)
> > lsk->sk_err = -rc;
> > diff --git a/net/smc/smc.h b/net/smc/smc.h
> > index 08786ace6010..9a2795cf5d30 100644
> > --- a/net/smc/smc.h
> > +++ b/net/smc/smc.h
> > @@ -219,6 +219,8 @@ struct smc_sock { /* smc sock container */
> > * started, waiting for unsent
> > * data to be sent
> > */
> > + struct mutex clcsock_release_lock;
> > + /* protects clcsock */
>
> I suggest to be more precise: "protects clcsock of a listen socket"
>
> > };
> >
> > static inline struct smc_sock *smc_sk(const struct sock *sk)
> >
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH v2] net/smc: fix TCP fallback socket release
2018-12-18 7:03 ` Myungho Jung
@ 2018-12-18 11:24 ` Ursula Braun
0 siblings, 0 replies; 4+ messages in thread
From: Ursula Braun @ 2018-12-18 11:24 UTC (permalink / raw)
To: Myungho Jung; +Cc: David S. Miller, linux-s390, netdev, linux-kernel
On 12/18/2018 08:03 AM, Myungho Jung wrote:
> On Mon, Dec 17, 2018 at 03:58:58PM +0100, Ursula Braun wrote:
>>
>
> Hi Ursula,
>
> Thank you for your suggestion. I have a question on your comment.
>
>>
>> On 12/17/2018 06:21 AM, Myungho Jung wrote:
>>> clcsock can be released while kernel_accept() references it in TCP
>>> listen worker. Also, clcsock needs to wake up before released if TCP
>>> fallback is used and the clcsock is blocked by accept. Add a lock to
>>> safely release clcsock and call kernel_sock_shutdown() to wake up
>>> clcsock from accept in smc_release().
>>
>> Thanks for your effort to solve this problem. I have some minor
>> improvement proposals:
>>
>>>
>>> Reported-by: syzbot+0bf2e01269f1274b4b03@syzkaller.appspotmail.com
>>> Reported-by: syzbot+e3132895630f957306bc@syzkaller.appspotmail.com
>>> Signed-off-by: Myungho Jung <mhjungk@gmail.com>
>>> ---
>>> net/smc/af_smc.c | 14 ++++++++++++--
>>> net/smc/smc.h | 2 ++
>>> 2 files changed, 14 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
>>> index 5fbaf1901571..5d06fb1bbccf 100644
>>> --- a/net/smc/af_smc.c
>>> +++ b/net/smc/af_smc.c
>>> @@ -147,8 +147,14 @@ static int smc_release(struct socket *sock)
>>> sk->sk_shutdown |= SHUTDOWN_MASK;
>>> }
>>> if (smc->clcsock) {
>>> + if (smc->use_fallback && sk->sk_state == SMC_LISTEN) {
>>> + /* wake up clcsock accept */
>>> + rc = kernel_sock_shutdown(smc->clcsock, SHUT_RDWR);
>>> + }
>>
>> This part is not needed, since an SMC socket in state SMC_LISTEN is never
>> a use_fallback socket.
>
> In smc_sendmsg(), set use_fallback to true if SMC socket is SMC_INIT
> state and the message has MSG_FASTOPEN flag. After this, smc_listen()
> would trigger smc_tcp_listen_work(). Is this not an expected scenario?
> Then, what is the reason for not skipping smc_sendmsg() in SMC_INIT
> state?
>
You are right, I have not had the FASTOPEN case in mind, sorry. If we want
to allow fallback in case of FASTOPEN, we need the kernel_sock_shutdown() here
for proper cleanup. Nice!
>>
>>> + mutex_lock(&smc->clcsock_release_lock);
>>> sock_release(smc->clcsock);
>>> smc->clcsock = NULL;
>>> + mutex_unlock(&smc->clcsock_release_lock);
>>> }
>>> if (smc->use_fallback) {
>>> if (sk->sk_state != SMC_LISTEN && sk->sk_state != SMC_INIT)
>>> @@ -205,6 +211,7 @@ static struct sock *smc_sock_alloc(struct net *net, struct socket *sock,
>>> spin_lock_init(&smc->conn.send_lock);
>>> sk->sk_prot->hash(sk);
>>> sk_refcnt_debug_inc(sk);
>>> + mutex_init(&smc->clcsock_release_lock);
>>>
>>> return sk;
>>> }
>>> @@ -821,7 +828,7 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
>>> struct socket *new_clcsock = NULL;
>>> struct sock *lsk = &lsmc->sk;
>>> struct sock *new_sk;
>>> - int rc;
>>> + int rc = 0;
>>
>> Without clcsock the good path should not be executed. Thus I suggest
>> to initialize with something negative like -EINVAL.
>>
>>>
>>> release_sock(lsk);
>>> new_sk = smc_sock_alloc(sock_net(lsk), NULL, lsk->sk_protocol);
>>> @@ -834,7 +841,10 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
>>> }
>>> *new_smc = smc_sk(new_sk);
>>>
>>> - rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0);
>>> + mutex_lock(&lsmc->clcsock_release_lock);
>>> + if (lsmc->clcsock)
>>> + rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0);
>>> + mutex_unlock(&lsmc->clcsock_release_lock);
>>> lock_sock(lsk);
>>> if (rc < 0)
>>> lsk->sk_err = -rc;
>>> diff --git a/net/smc/smc.h b/net/smc/smc.h
>>> index 08786ace6010..9a2795cf5d30 100644
>>> --- a/net/smc/smc.h
>>> +++ b/net/smc/smc.h
>>> @@ -219,6 +219,8 @@ struct smc_sock { /* smc sock container */
>>> * started, waiting for unsent
>>> * data to be sent
>>> */
>>> + struct mutex clcsock_release_lock;
>>> + /* protects clcsock */
>>
>> I suggest to be more precise: "protects clcsock of a listen socket"
>>
>>> };
>>>
>>> static inline struct smc_sock *smc_sk(const struct sock *sk)
>>>
>>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-12-18 11:24 UTC | newest]
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2018-12-17 5:21 [PATCH v2] net/smc: fix TCP fallback socket release Myungho Jung
2018-12-17 14:58 ` Ursula Braun
2018-12-18 7:03 ` Myungho Jung
2018-12-18 11:24 ` Ursula Braun
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