2023-04-20 18:10:58

by Ivan Vecera

Subject: [PATCH net] net/sched: cls_api: Initialize miss_cookie_node when action miss is not used

Function tcf_exts_init_ex() sets exts->miss_cookie_node ptr only
when use_action_miss is true so it assumes in other case that
the field is set to NULL by the caller. If not then the field
contains garbage and subsequent tcf_exts_destroy() call results
in a crash.
Initialize .miss_cookie_node pointer to NULL when use_action_miss
parameter is false to avoid this potential scenario.

Fixes: 80cd22c35c90 ("net/sched: cls_api: Support hardware miss to tc action")
Signed-off-by: Ivan Vecera <[email protected]>
---
net/sched/cls_api.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 35785a36c80298..8bc5b9d6a2916e 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -3224,8 +3224,12 @@ int tcf_exts_init_ex(struct tcf_exts *exts, struct net *net, int action,
exts->action = action;
exts->police = police;

- if (!use_action_miss)
+ if (!use_action_miss) {
+#ifdef CONFIG_NET_CLS_ACT
+ exts->miss_cookie_node = NULL;
+#endif
return 0;
+ }

err = tcf_exts_miss_cookie_base_alloc(exts, tp, handle);
if (err)
--
2.39.2

2023-04-20 18:23:42

by Pedro Tammela

Subject: Re: [PATCH net] net/sched: cls_api: Initialize miss_cookie_node when action miss is not used

On 20/04/2023 14:59, Ivan Vecera wrote:
> Function tcf_exts_init_ex() sets exts->miss_cookie_node ptr only
> when use_action_miss is true so it assumes in other case that
> the field is set to NULL by the caller. If not then the field
> contains garbage and subsequent tcf_exts_destroy() call results
> in a crash.
> Initialize .miss_cookie_node pointer to NULL when use_action_miss
> parameter is false to avoid this potential scenario.
>
> Fixes: 80cd22c35c90 ("net/sched: cls_api: Support hardware miss to tc action")
> Signed-off-by: Ivan Vecera <[email protected]>
> ---
> net/sched/cls_api.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
> index 35785a36c80298..8bc5b9d6a2916e 100644
> --- a/net/sched/cls_api.c
> +++ b/net/sched/cls_api.c
> @@ -3224,8 +3224,12 @@ int tcf_exts_init_ex(struct tcf_exts *exts, struct net *net, int action,
> exts->action = action;
> exts->police = police;
>
> - if (!use_action_miss)
> + if (!use_action_miss) {
> +#ifdef CONFIG_NET_CLS_ACT
> + exts->miss_cookie_node = NULL;
> +#endif
> return 0;
> + }
>
> err = tcf_exts_miss_cookie_base_alloc(exts, tp, handle);
> if (err)

The problem described here also happens in the case some error happens
if the action array allocation fails and before the 'miss_cookie_node'
assignment inside 'tcf_exts_miss_cookie_base_alloc()'.

Seems like a better way to solve this issue is to just:
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 35785a36c802..3c3629c9e7b6 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -3211,6 +3211,7 @@ int tcf_exts_init_ex(struct tcf_exts *exts, struct
net *net, int action,
#ifdef CONFIG_NET_CLS_ACT
exts->type = 0;
exts->nr_actions = 0;
+ exts->miss_cookie_node = NULL;
/* Note: we do not own yet a reference on net.
* This reference might be taken later from tcf_exts_get_net().
*/

2023-04-20 18:53:11

by Ivan Vecera

Subject: Re: [PATCH net] net/sched: cls_api: Initialize miss_cookie_node when action miss is not used

On 20. 04. 23 20:21, Pedro Tammela wrote:
> On 20/04/2023 14:59, Ivan Vecera wrote:
>> Function tcf_exts_init_ex() sets exts->miss_cookie_node ptr only
>> when use_action_miss is true so it assumes in other case that
>> the field is set to NULL by the caller. If not then the field
>> contains garbage and subsequent tcf_exts_destroy() call results
>> in a crash.
>> Initialize .miss_cookie_node pointer to NULL when use_action_miss
>> parameter is false to avoid this potential scenario.
>>
>> Fixes: 80cd22c35c90 ("net/sched: cls_api: Support hardware miss to tc
>> action")
>> Signed-off-by: Ivan Vecera <[email protected]>
>> ---
>>   net/sched/cls_api.c | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
>> index 35785a36c80298..8bc5b9d6a2916e 100644
>> --- a/net/sched/cls_api.c
>> +++ b/net/sched/cls_api.c
>> @@ -3224,8 +3224,12 @@ int tcf_exts_init_ex(struct tcf_exts *exts,
>> struct net *net, int action,
>>       exts->action = action;
>>       exts->police = police;
>> -    if (!use_action_miss)
>> +    if (!use_action_miss) {
>> +#ifdef CONFIG_NET_CLS_ACT
>> +        exts->miss_cookie_node = NULL;
>> +#endif
>>           return 0;
>> +    }
>>       err = tcf_exts_miss_cookie_base_alloc(exts, tp, handle);
>>       if (err)
>
> The problem described here also happens in the case some error happens
> if the action array allocation fails and before the 'miss_cookie_node'
> assignment inside 'tcf_exts_miss_cookie_base_alloc()'.
>
> Seems like a better way to solve this issue is to just:
> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
> index 35785a36c802..3c3629c9e7b6 100644
> --- a/net/sched/cls_api.c
> +++ b/net/sched/cls_api.c
> @@ -3211,6 +3211,7 @@ int tcf_exts_init_ex(struct tcf_exts *exts, struct
> net *net, int action,
>  #ifdef CONFIG_NET_CLS_ACT
>         exts->type = 0;
>         exts->nr_actions = 0;
> +       exts->miss_cookie_node = NULL;
>         /* Note: we do not own yet a reference on net.
>          * This reference might be taken later from tcf_exts_get_net().
>          */

Looks better, will repost...

Thanks

Ivan