2021-06-07 19:43:43

by Pavel Skripkin

Subject: [PATCH] net: rds: fix memory leak in rds_recvmsg

Syzbot reported memory leak in rds. The problem
was in unputted refcount in case of error.

int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
int msg_flags)
{
...

if (!rds_next_incoming(rs, &inc)) {
...
}

After this "if" inc refcount incremented and

if (rds_cmsg_recv(inc, msg, rs)) {
ret = -EFAULT;
goto out;
}
...
out:
return ret;
}

in case of rds_cmsg_recv() fail the refcount won't be
decremented. And it's easy to see from ftrace log, that
rds_inc_addref() don't have rds_inc_put() pair in
rds_recvmsg() after rds_cmsg_recv()

1) | rds_recvmsg() {
1) 3.721 us | rds_inc_addref();
1) 3.853 us | rds_message_inc_copy_to_user();
1) + 10.395 us | rds_cmsg_recv();
1) + 34.260 us | }

Fixes: bdbe6fbc6a2f ("RDS: recv.c")
Reported-and-tested-by: [email protected]
Signed-off-by: Pavel Skripkin <[email protected]>
---
net/rds/recv.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/rds/recv.c b/net/rds/recv.c
index 4db109fb6ec2..3fa16c339bfe 100644
--- a/net/rds/recv.c
+++ b/net/rds/recv.c
@@ -714,7 +714,7 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,

if (rds_cmsg_recv(inc, msg, rs)) {
ret = -EFAULT;
- goto out;
+ goto out_put;
}
rds_recvmsg_zcookie(rs, msg);

@@ -740,6 +740,7 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
break;
}

+out_put:
if (inc)
rds_inc_put(inc);

--
2.31.1

2021-06-08 07:12:55

by Håkon Bugge

Subject: Re: [PATCH] net: rds: fix memory leak in rds_recvmsg

> On 7 Jun 2021, at 21:41, Pavel Skripkin <[email protected]> wrote:
>
> Syzbot reported memory leak in rds. The problem
> was in unputted refcount in case of error.
>
> int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
> int msg_flags)
> {
> ...
>
> if (!rds_next_incoming(rs, &inc)) {
> ...
> }
>
> After this "if" inc refcount incremented and
>
> if (rds_cmsg_recv(inc, msg, rs)) {
> ret = -EFAULT;
> goto out;
> }
> ...
> out:
> return ret;
> }
>
> in case of rds_cmsg_recv() fail the refcount won't be
> decremented. And it's easy to see from ftrace log, that
> rds_inc_addref() don't have rds_inc_put() pair in
> rds_recvmsg() after rds_cmsg_recv()
>
> 1) | rds_recvmsg() {
> 1) 3.721 us | rds_inc_addref();
> 1) 3.853 us | rds_message_inc_copy_to_user();
> 1) + 10.395 us | rds_cmsg_recv();
> 1) + 34.260 us | }
>
> Fixes: bdbe6fbc6a2f ("RDS: recv.c")
> Reported-and-tested-by: [email protected]
> Signed-off-by: Pavel Skripkin <[email protected]>

Thank for your commit and analyses. One small nit below.

> ---
> net/rds/recv.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/rds/recv.c b/net/rds/recv.c
> index 4db109fb6ec2..3fa16c339bfe 100644
> --- a/net/rds/recv.c
> +++ b/net/rds/recv.c
> @@ -714,7 +714,7 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
>
> if (rds_cmsg_recv(inc, msg, rs)) {
> ret = -EFAULT;
> - goto out;
> + goto out_put;

Would a simple "break;" do it here and no need for the next hunk?


Thxs, Håkon

> }
> rds_recvmsg_zcookie(rs, msg);
>
> @@ -740,6 +740,7 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
> break;
> }
>
> +out_put:
> if (inc)
> rds_inc_put(inc);
>
> --
> 2.31.1
>

2021-06-08 08:01:46

by Pavel Skripkin

Subject: Re: [PATCH] net: rds: fix memory leak in rds_recvmsg

On Tue, 8 Jun 2021 07:11:27 +0000
Haakon Bugge <[email protected]> wrote:

>
>
> > On 7 Jun 2021, at 21:41, Pavel Skripkin <[email protected]>
> > wrote:
> >
> > Syzbot reported memory leak in rds. The problem
> > was in unputted refcount in case of error.
> >
> > int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t
> > size, int msg_flags)
> > {
> > ...
> >
> > if (!rds_next_incoming(rs, &inc)) {
> > ...
> > }
> >
> > After this "if" inc refcount incremented and
> >
> > if (rds_cmsg_recv(inc, msg, rs)) {
> > ret = -EFAULT;
> > goto out;
> > }
> > ...
> > out:
> > return ret;
> > }
> >
> > in case of rds_cmsg_recv() fail the refcount won't be
> > decremented. And it's easy to see from ftrace log, that
> > rds_inc_addref() don't have rds_inc_put() pair in
> > rds_recvmsg() after rds_cmsg_recv()
> >
> > 1) | rds_recvmsg() {
> > 1) 3.721 us | rds_inc_addref();
> > 1) 3.853 us | rds_message_inc_copy_to_user();
> > 1) + 10.395 us | rds_cmsg_recv();
> > 1) + 34.260 us | }
> >
> > Fixes: bdbe6fbc6a2f ("RDS: recv.c")
> > Reported-and-tested-by:
> > [email protected]
> > Signed-off-by: Pavel Skripkin <[email protected]>
>
> Thank for your commit and analyses. One small nit below.
>
> > ---
> > net/rds/recv.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/rds/recv.c b/net/rds/recv.c
> > index 4db109fb6ec2..3fa16c339bfe 100644
> > --- a/net/rds/recv.c
> > +++ b/net/rds/recv.c
> > @@ -714,7 +714,7 @@ int rds_recvmsg(struct socket *sock, struct
> > msghdr *msg, size_t size,
> >
> > if (rds_cmsg_recv(inc, msg, rs)) {
> > ret = -EFAULT;
> > - goto out;
> > + goto out_put;
>
> Would a simple "break;" do it here and no need for the next hunk?
>
>
> Thxs, Håkon
>

Sure! I'll send v2 soon. Thank you for feedback :)


With regards,
Pavel Skripkin

2021-06-08 08:11:02

by Pavel Skripkin

Subject: [PATCH v2] net: rds: fix memory leak in rds_recvmsg

Syzbot reported memory leak in rds. The problem
was in unputted refcount in case of error.

int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
int msg_flags)
{
...

if (!rds_next_incoming(rs, &inc)) {
...
}

After this "if" inc refcount incremented and

if (rds_cmsg_recv(inc, msg, rs)) {
ret = -EFAULT;
goto out;
}
...
out:
return ret;
}

in case of rds_cmsg_recv() fail the refcount won't be
decremented. And it's easy to see from ftrace log, that
rds_inc_addref() don't have rds_inc_put() pair in
rds_recvmsg() after rds_cmsg_recv()

1) | rds_recvmsg() {
1) 3.721 us | rds_inc_addref();
1) 3.853 us | rds_message_inc_copy_to_user();
1) + 10.395 us | rds_cmsg_recv();
1) + 34.260 us | }

Fixes: bdbe6fbc6a2f ("RDS: recv.c")
Reported-and-tested-by: [email protected]
Signed-off-by: Pavel Skripkin <[email protected]>
---

Changes in v2:
Changed goto to break.

---
net/rds/recv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/rds/recv.c b/net/rds/recv.c
index 4db109fb6ec2..5b426dc3634d 100644
--- a/net/rds/recv.c
+++ b/net/rds/recv.c
@@ -714,7 +714,7 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,

if (rds_cmsg_recv(inc, msg, rs)) {
ret = -EFAULT;
- goto out;
+ break;
}
rds_recvmsg_zcookie(rs, msg);

--
2.31.1

2021-06-09 00:27:15

by Håkon Bugge

Subject: Re: [PATCH v2] net: rds: fix memory leak in rds_recvmsg

> On 8 Jun 2021, at 10:06, Pavel Skripkin <[email protected]> wrote:
>
> Syzbot reported memory leak in rds. The problem
> was in unputted refcount in case of error.
>
> int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
> int msg_flags)
> {
> ...
>
> if (!rds_next_incoming(rs, &inc)) {
> ...
> }
>
> After this "if" inc refcount incremented and
>
> if (rds_cmsg_recv(inc, msg, rs)) {
> ret = -EFAULT;
> goto out;
> }
> ...
> out:
> return ret;
> }
>
> in case of rds_cmsg_recv() fail the refcount won't be
> decremented. And it's easy to see from ftrace log, that
> rds_inc_addref() don't have rds_inc_put() pair in
> rds_recvmsg() after rds_cmsg_recv()
>
> 1) | rds_recvmsg() {
> 1) 3.721 us | rds_inc_addref();
> 1) 3.853 us | rds_message_inc_copy_to_user();
> 1) + 10.395 us | rds_cmsg_recv();
> 1) + 34.260 us | }
>
> Fixes: bdbe6fbc6a2f ("RDS: recv.c")
> Reported-and-tested-by: [email protected]
> Signed-off-by: Pavel Skripkin <[email protected]>

Reviewed-by: Håkon Bugge <[email protected]>


Thanks for fixing this, Håkon

> ---
>
> Changes in v2:
> Changed goto to break.
>
> ---
> net/rds/recv.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/rds/recv.c b/net/rds/recv.c
> index 4db109fb6ec2..5b426dc3634d 100644
> --- a/net/rds/recv.c
> +++ b/net/rds/recv.c
> @@ -714,7 +714,7 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
>
> if (rds_cmsg_recv(inc, msg, rs)) {
> ret = -EFAULT;
> - goto out;
> + break;
> }
> rds_recvmsg_zcookie(rs, msg);
>
> --
> 2.31.1
>

2021-06-09 03:11:46

by Santosh Shilimkar

Subject: Re: [PATCH v2] net: rds: fix memory leak in rds_recvmsg

On Jun 8, 2021, at 1:06 AM, Pavel Skripkin <[email protected]> wrote:
>
> Syzbot reported memory leak in rds. The problem
> was in unputted refcount in case of error.
>
> int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
> int msg_flags)
> {
> ...
>
> if (!rds_next_incoming(rs, &inc)) {
> ...
> }
>
> After this "if" inc refcount incremented and
>
> if (rds_cmsg_recv(inc, msg, rs)) {
> ret = -EFAULT;
> goto out;
> }
> ...
> out:
> return ret;
> }
>
> in case of rds_cmsg_recv() fail the refcount won't be
> decremented. And it's easy to see from ftrace log, that
> rds_inc_addref() don't have rds_inc_put() pair in
> rds_recvmsg() after rds_cmsg_recv()
>
> 1) | rds_recvmsg() {
> 1) 3.721 us | rds_inc_addref();
> 1) 3.853 us | rds_message_inc_copy_to_user();
> 1) + 10.395 us | rds_cmsg_recv();
> 1) + 34.260 us | }
>
> Fixes: bdbe6fbc6a2f ("RDS: recv.c")
> Reported-and-tested-by: [email protected]
> Signed-off-by: Pavel Skripkin <[email protected]>
> ---
>
> Changes in v2:
> Changed goto to break.
>
Looks fine by me. Thanks for the fix.

Acked-by: Santosh Shilimkar <[email protected]>

2021-06-09 16:56:05

by patchwork-bot+netdevbpf

Subject: Re: [PATCH v2] net: rds: fix memory leak in rds_recvmsg

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Tue, 8 Jun 2021 11:06:41 +0300 you wrote:
> Syzbot reported memory leak in rds. The problem
> was in unputted refcount in case of error.
>
> int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
> int msg_flags)
> {
> ...
>
> [...]

Here is the summary with links:
- [v2] net: rds: fix memory leak in rds_recvmsg
https://git.kernel.org/netdev/net/c/49bfcbfd989a

You are awesome, thank you!
--
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