[PATCH] net: qrtr: fix memory leak in qrtr_local_enqueue

[PATCH] net: qrtr: fix memory leak in qrtr_local_enqueue

[Pavel Skripkin]

Syzbot reported memory leak in qrtr. The problem was in unputted
struct sock. qrtr_local_enqueue() function calls qrtr_port_lookup()
which takes sock reference if port was found. Then there is the following
check:

if (!ipc || &ipc->sk == skb->sk) {
	...
	return -ENODEV;
}

Since we should drop the reference before returning from this function and
ipc can be non-NULL inside this if, we should add qrtr_port_put() inside
this if.

Fixes: bdabad3e363d ("net: Add Qualcomm IPC router")
Reported-and-tested-by: syzbot+35a511c72ea7356cdcf3@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
 net/qrtr/qrtr.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
index e6f4a6202f82..d5ce428d0b25 100644
--- a/net/qrtr/qrtr.c
+++ b/net/qrtr/qrtr.c
@@ -839,6 +839,8 @@ static int qrtr_local_enqueue(struct qrtr_node *node, struct sk_buff *skb,
 
 	ipc = qrtr_port_lookup(to->sq_port);
 	if (!ipc || &ipc->sk == skb->sk) { /* do not send to self */
+		if (ipc)
+			qrtr_port_put(ipc);
 		kfree_skb(skb);
 		return -ENODEV;
 	}
-- 
2.32.0

Re: [PATCH] net: qrtr: fix memory leak in qrtr_local_enqueue

[Manivannan Sadhasivam]

On Thu, Jul 22, 2021 at 07:16:25PM +0300, Pavel Skripkin wrote:
> Syzbot reported memory leak in qrtr. The problem was in unputted
> struct sock. qrtr_local_enqueue() function calls qrtr_port_lookup()
> which takes sock reference if port was found. Then there is the following
> check:
> 
> if (!ipc || &ipc->sk == skb->sk) {
> 	...
> 	return -ENODEV;
> }
> 
> Since we should drop the reference before returning from this function and
> ipc can be non-NULL inside this if, we should add qrtr_port_put() inside
> this if.
> 
> Fixes: bdabad3e363d ("net: Add Qualcomm IPC router")
> Reported-and-tested-by: syzbot+35a511c72ea7356cdcf3@syzkaller.appspotmail.com
> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>

Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>

It'd be good if this patch can be extended to fix one more corner case here:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/qrtr/qrtr.c#n522

Thanks,
Mani

> ---
>  net/qrtr/qrtr.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
> index e6f4a6202f82..d5ce428d0b25 100644
> --- a/net/qrtr/qrtr.c
> +++ b/net/qrtr/qrtr.c
> @@ -839,6 +839,8 @@ static int qrtr_local_enqueue(struct qrtr_node *node, struct sk_buff *skb,
>  
>  	ipc = qrtr_port_lookup(to->sq_port);
>  	if (!ipc || &ipc->sk == skb->sk) { /* do not send to self */
> +		if (ipc)
> +			qrtr_port_put(ipc);
>  		kfree_skb(skb);
>  		return -ENODEV;
>  	}
> -- 
> 2.32.0
> 

Re: [PATCH] net: qrtr: fix memory leak in qrtr_local_enqueue

[Pavel Skripkin]

On Fri, 23 Jul 2021 17:57:53 +0530
Manivannan Sadhasivam <mani@kernel.org> wrote:

> On Thu, Jul 22, 2021 at 07:16:25PM +0300, Pavel Skripkin wrote:
> > Syzbot reported memory leak in qrtr. The problem was in unputted
> > struct sock. qrtr_local_enqueue() function calls qrtr_port_lookup()
> > which takes sock reference if port was found. Then there is the
> > following check:
> > 
> > if (!ipc || &ipc->sk == skb->sk) {
> > 	...
> > 	return -ENODEV;
> > }
> > 
> > Since we should drop the reference before returning from this
> > function and ipc can be non-NULL inside this if, we should add
> > qrtr_port_put() inside this if.
> > 
> > Fixes: bdabad3e363d ("net: Add Qualcomm IPC router")
> > Reported-and-tested-by:
> > syzbot+35a511c72ea7356cdcf3@syzkaller.appspotmail.com
> > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
> 
> Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
> 
> It'd be good if this patch can be extended to fix one more corner
> case here:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/qrtr/qrtr.c#n522
> 
> Thanks,
> Mani

Hi, Manivannan!

I will fix leak there too in v2, thank you! 



With regards,
Pavel Skripkin

> 
> > ---
> >  net/qrtr/qrtr.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
> > index e6f4a6202f82..d5ce428d0b25 100644
> > --- a/net/qrtr/qrtr.c
> > +++ b/net/qrtr/qrtr.c
> > @@ -839,6 +839,8 @@ static int qrtr_local_enqueue(struct qrtr_node
> > *node, struct sk_buff *skb, 
> >  	ipc = qrtr_port_lookup(to->sq_port);
> >  	if (!ipc || &ipc->sk == skb->sk) { /* do not send to self
> > */
> > +		if (ipc)
> > +			qrtr_port_put(ipc);
> >  		kfree_skb(skb);
> >  		return -ENODEV;
> >  	}
> > -- 
> > 2.32.0
> >