2023-10-11 05:12:56

by Anjali Kulkarni

Subject: [PATCH v2] Fix NULL pointer deref due to filtering on fork

cn_netlink_send_mult() should be called with filter & filter_data only
for EXIT case. For all other events, filter & filter_data should be
NULL.

Fixes: 2aa1f7a1f47c ("connector/cn_proc: Add filtering to fix some bugs")
Reported-by: kernel test robot <[email protected]>
Closes: https://urldefense.com/v3/__https://lore.kernel.org/oe-lkp/[email protected]__;!!ACWV5N9M2RV99hQ!PgqlHq_nOe_KlyKkB9Mm_S8QstTJvicjuENwskatuuQK05KPuFw-KvRZeOH8iuEAMjRhkxEMPKJJnLcaT8zrPf9aqNs$

Signed-off-by: Anjali Kulkarni <[email protected]>
---
drivers/connector/cn_proc.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
index 05d562e9c8b1..01e17f18d187 100644
--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -104,13 +104,13 @@ static inline void send_msg(struct cn_msg *msg)
if (filter_data[0] == PROC_EVENT_EXIT) {
filter_data[1] =
((struct proc_event *)msg->data)->event_data.exit.exit_code;
+ cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
+ cn_filter, (void *)filter_data);
} else {
- filter_data[1] = 0;
+ cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
+ NULL, NULL);
}

- cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
- cn_filter, (void *)filter_data);
-
local_unlock(&local_event.lock);
}

--
2.42.0

2023-10-13 12:02:22

by Simon Horman

Subject: Re: [PATCH v2] Fix NULL pointer deref due to filtering on fork

On Tue, Oct 10, 2023 at 10:12:25PM -0700, Anjali Kulkarni wrote:
> cn_netlink_send_mult() should be called with filter & filter_data only
> for EXIT case. For all other events, filter & filter_data should be
> NULL.
>
> Fixes: 2aa1f7a1f47c ("connector/cn_proc: Add filtering to fix some bugs")
> Reported-by: kernel test robot <[email protected]>
> Closes: https://urldefense.com/v3/__https://lore.kernel.org/oe-lkp/[email protected]__;!!ACWV5N9M2RV99hQ!PgqlHq_nOe_KlyKkB9Mm_S8QstTJvicjuENwskatuuQK05KPuFw-KvRZeOH8iuEAMjRhkxEMPKJJnLcaT8zrPf9aqNs$

For the record, this got a bit mangled. I believe it should be:

Closes: https://lore.kernel.org/oe-lkp/[email protected]/

Also, there is probably no need to resend because of this,
but no blank line here, please.

> Signed-off-by: Anjali Kulkarni <[email protected]>
> ---
> drivers/connector/cn_proc.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
> index 05d562e9c8b1..01e17f18d187 100644
> --- a/drivers/connector/cn_proc.c
> +++ b/drivers/connector/cn_proc.c
> @@ -104,13 +104,13 @@ static inline void send_msg(struct cn_msg *msg)
> if (filter_data[0] == PROC_EVENT_EXIT) {
> filter_data[1] =
> ((struct proc_event *)msg->data)->event_data.exit.exit_code;
> + cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
> + cn_filter, (void *)filter_data);
> } else {
> - filter_data[1] = 0;
> + cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
> + NULL, NULL);
> }
>
> - cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
> - cn_filter, (void *)filter_data);
> -

I am wondering if you considered making cn_filter slightly smarter.
It seems it already understands not to do very much for PROC_EVENT_ALL.

> local_unlock(&local_event.lock);
> }
>
> --
> 2.42.0
>
>

2023-10-13 16:19:23

by Anjali Kulkarni

Subject: Re: [PATCH v2] Fix NULL pointer deref due to filtering on fork

> On Oct 13, 2023, at 5:01 AM, Simon Horman <[email protected]> wrote:
>
> On Tue, Oct 10, 2023 at 10:12:25PM -0700, Anjali Kulkarni wrote:
>> cn_netlink_send_mult() should be called with filter & filter_data only
>> for EXIT case. For all other events, filter & filter_data should be
>> NULL.
>>
>> Fixes: 2aa1f7a1f47c ("connector/cn_proc: Add filtering to fix some bugs")
>> Reported-by: kernel test robot <[email protected]>
>> Closes: https://urldefense.com/v3/__https://lore.kernel.org/oe-lkp/[email protected]__;!!ACWV5N9M2RV99hQ!PgqlHq_nOe_KlyKkB9Mm_S8QstTJvicjuENwskatuuQK05KPuFw-KvRZeOH8iuEAMjRhkxEMPKJJnLcaT8zrPf9aqNs$
>
> For the record, this got a bit mangled. I believe it should be:
>
> Closes: https://lore.kernel.org/oe-lkp/[email protected]/
>
> Also, there is probably no need to resend because of this,
> but no blank line here, please.

Ok.

>
>> Signed-off-by: Anjali Kulkarni <[email protected]>
>> ---
>> drivers/connector/cn_proc.c | 8 ++++----
>> 1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
>> index 05d562e9c8b1..01e17f18d187 100644
>> --- a/drivers/connector/cn_proc.c
>> +++ b/drivers/connector/cn_proc.c
>> @@ -104,13 +104,13 @@ static inline void send_msg(struct cn_msg *msg)
>> if (filter_data[0] == PROC_EVENT_EXIT) {
>> filter_data[1] =
>> ((struct proc_event *)msg->data)->event_data.exit.exit_code;
>> + cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
>> + cn_filter, (void *)filter_data);
>> } else {
>> - filter_data[1] = 0;
>> + cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
>> + NULL, NULL);
>> }
>>
>> - cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
>> - cn_filter, (void *)filter_data);
>> -
>
> I am wondering if you considered making cn_filter slightly smarter.
> It seems it already understands not to do very much for PROC_EVENT_ALL.

I could, but then we would be unnecessarily make an extra function call to cn_filter, and re-check this condition, which can be avoided if we do the check here.

>
>> local_unlock(&local_event.lock);
>> }
>>
>> --
>> 2.42.0

2023-10-13 23:01:52

by Anjali Kulkarni

Subject: Re: [PATCH v2] Fix NULL pointer deref due to filtering on fork

Please discard this patch,

Anjali

> On Oct 13, 2023, at 5:01 AM, Simon Horman <[email protected]> wrote:
>
> On Tue, Oct 10, 2023 at 10:12:25PM -0700, Anjali Kulkarni wrote:
>> cn_netlink_send_mult() should be called with filter & filter_data only
>> for EXIT case. For all other events, filter & filter_data should be
>> NULL.
>>
>> Fixes: 2aa1f7a1f47c ("connector/cn_proc: Add filtering to fix some bugs")
>> Reported-by: kernel test robot <[email protected]>
>> Closes: https://urldefense.com/v3/__https://lore.kernel.org/oe-lkp/[email protected]__;!!ACWV5N9M2RV99hQ!PgqlHq_nOe_KlyKkB9Mm_S8QstTJvicjuENwskatuuQK05KPuFw-KvRZeOH8iuEAMjRhkxEMPKJJnLcaT8zrPf9aqNs$
>
> For the record, this got a bit mangled. I believe it should be:
>
> Closes: https://lore.kernel.org/oe-lkp/[email protected]/
>
> Also, there is probably no need to resend because of this,
> but no blank line here, please.
>
>> Signed-off-by: Anjali Kulkarni <[email protected]>
>> ---
>> drivers/connector/cn_proc.c | 8 ++++----
>> 1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
>> index 05d562e9c8b1..01e17f18d187 100644
>> --- a/drivers/connector/cn_proc.c
>> +++ b/drivers/connector/cn_proc.c
>> @@ -104,13 +104,13 @@ static inline void send_msg(struct cn_msg *msg)
>> if (filter_data[0] == PROC_EVENT_EXIT) {
>> filter_data[1] =
>> ((struct proc_event *)msg->data)->event_data.exit.exit_code;
>> + cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
>> + cn_filter, (void *)filter_data);
>> } else {
>> - filter_data[1] = 0;
>> + cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
>> + NULL, NULL);
>> }
>>
>> - cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
>> - cn_filter, (void *)filter_data);
>> -
>
> I am wondering if you considered making cn_filter slightly smarter.
> It seems it already understands not to do very much for PROC_EVENT_ALL.
>
>> local_unlock(&local_event.lock);
>> }
>>
>> --
>> 2.42.0