[PATCH net] net: sched: Don't free f before it is allocated in route4_change

[PATCH net] net: sched: Don't free f before it is allocated in route4_change

[Christoph Paasch]

f is set to *arg in route4_change at the beginning, which points to a
route4_filter in the hash-table (gotten through route4_get, called by
tc_ctl_filter). If the alloc of head fails, we should not goto errout,
because this will free f and thus freed memory will be referenced by
the hash-table.
Only later the pointer f will change to an allocated route4_filter.

This patch returns err if the allocation of head fails as f has not yet
been allocated inside route4_change.

Seems the code has been like this since Linus's original git-commit.

Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
---
 net/sched/cls_route.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/cls_route.c b/net/sched/cls_route.c
index 37da567..f17c67f 100644
--- a/net/sched/cls_route.c
+++ b/net/sched/cls_route.c
@@ -470,7 +470,7 @@ static int route4_change(struct net *net, struct sk_buff *in_skb,
 	if (head == NULL) {
 		head = kzalloc(sizeof(struct route4_head), GFP_KERNEL);
 		if (head == NULL)
-			goto errout;
+			return err;
 
 		tcf_tree_lock(tp);
 		tp->root = head;
-- 
1.8.3.2

Re: [PATCH net] net: sched: Don't free f before it is allocated in route4_change

[Eric Dumazet]

On Thu, 2013-10-24 at 16:50 +0200, Christoph Paasch wrote:
> f is set to *arg in route4_change at the beginning, which points to a
> route4_filter in the hash-table (gotten through route4_get, called by
> tc_ctl_filter). If the alloc of head fails, we should not goto errout,
> because this will free f and thus freed memory will be referenced by
> the hash-table.
> Only later the pointer f will change to an allocated route4_filter.
> 
> This patch returns err if the allocation of head fails as f has not yet
> been allocated inside route4_change.
> 
> Seems the code has been like this since Linus's original git-commit.
> 
> Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
> ---
>  net/sched/cls_route.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/sched/cls_route.c b/net/sched/cls_route.c
> index 37da567..f17c67f 100644
> --- a/net/sched/cls_route.c
> +++ b/net/sched/cls_route.c
> @@ -470,7 +470,7 @@ static int route4_change(struct net *net, struct sk_buff *in_skb,
>  	if (head == NULL) {
>  		head = kzalloc(sizeof(struct route4_head), GFP_KERNEL);
>  		if (head == NULL)
> -			goto errout;
> +			return err;
>  
>  		tcf_tree_lock(tp);
>  		tp->root = head;

I see no bug here, you missed the "goto reinsert;"

Guys, if there are no bugs, could we calm down ?

Thanks !

Re: [PATCH net] net: sched: Don't free f before it is allocated in route4_change

[Christoph Paasch]

On 24/10/13 - 07:54:33, Eric Dumazet wrote:
> On Thu, 2013-10-24 at 16:50 +0200, Christoph Paasch wrote:
> > f is set to *arg in route4_change at the beginning, which points to a
> > route4_filter in the hash-table (gotten through route4_get, called by
> > tc_ctl_filter). If the alloc of head fails, we should not goto errout,
> > because this will free f and thus freed memory will be referenced by
> > the hash-table.
> > Only later the pointer f will change to an allocated route4_filter.
> > 
> > This patch returns err if the allocation of head fails as f has not yet
> > been allocated inside route4_change.
> > 
> > Seems the code has been like this since Linus's original git-commit.
> > 
> > Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
> > ---
> >  net/sched/cls_route.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/net/sched/cls_route.c b/net/sched/cls_route.c
> > index 37da567..f17c67f 100644
> > --- a/net/sched/cls_route.c
> > +++ b/net/sched/cls_route.c
> > @@ -470,7 +470,7 @@ static int route4_change(struct net *net, struct sk_buff *in_skb,
> >  	if (head == NULL) {
> >  		head = kzalloc(sizeof(struct route4_head), GFP_KERNEL);
> >  		if (head == NULL)
> > -			goto errout;
> > +			return err;
> >  
> >  		tcf_tree_lock(tp);
> >  		tp->root = head;
> 
> I see no bug here, you missed the "goto reinsert;"

Ups - sorry...

Re: [PATCH net] net: sched: Don't free f before it is allocated in route4_change

[Eric Dumazet]

On Thu, 2013-10-24 at 16:59 +0200, Christoph Paasch wrote:
> On 24/10/13 - 07:54:33, Eric Dumazet wrote:

> > I see no bug here, you missed the "goto reinsert;"
> 
> Ups - sorry...
> 

Yeah, trying to find bugs in Alexey code is really tricky ;)

Re: [PATCH net] net: sched: Don't free f before it is allocated in route4_change

[Christoph Paasch]

On 24/10/13 - 08:05:57, Eric Dumazet wrote:
> On Thu, 2013-10-24 at 16:59 +0200, Christoph Paasch wrote:
> > On 24/10/13 - 07:54:33, Eric Dumazet wrote:
> 
> > > I see no bug here, you missed the "goto reinsert;"
> > 
> > Ups - sorry...
> > 
> 
> Yeah, trying to find bugs in Alexey code is really tricky ;)

Yeah :)

Instead of the goto, a simple if {} else {} would have made it
more readable IMO.