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

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

[Pavel Skripkin]

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: syzbot+5134cdf021c4ed5aaa5f@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
 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

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

[Haakon Bugge]

> On 7 Jun 2021, at 21:41, Pavel Skripkin <paskripkin@gmail.com> 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: syzbot+5134cdf021c4ed5aaa5f@syzkaller.appspotmail.com
> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>

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
> 

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

[Pavel Skripkin]

On Tue, 8 Jun 2021 07:11:27 +0000
Haakon Bugge <haakon.bugge@oracle.com> wrote:

> 
> 
> > On 7 Jun 2021, at 21:41, Pavel Skripkin <paskripkin@gmail.com>
> > 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:
> > syzbot+5134cdf021c4ed5aaa5f@syzkaller.appspotmail.com
> > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
> 
> 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

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

[Pavel Skripkin]

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: syzbot+5134cdf021c4ed5aaa5f@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---

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

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

[Haakon Bugge]

> On 8 Jun 2021, at 10:06, Pavel Skripkin <paskripkin@gmail.com> 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: syzbot+5134cdf021c4ed5aaa5f@syzkaller.appspotmail.com
> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>

Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>


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
> 

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

[Santosh Shilimkar]

On Jun 8, 2021, at 1:06 AM, Pavel Skripkin <paskripkin@gmail.com> 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: syzbot+5134cdf021c4ed5aaa5f@syzkaller.appspotmail.com
> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
> ---
> 
> Changes in v2:
> 	Changed goto to break.
> 
Looks fine by me. Thanks for the fix.

Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>

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

[patchwork-bot+netdevbpf]

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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