get_family_id() walks the generic netlink CTRL_CMD_GETFAMILY reply
looking for the CTRL_ATTR_FAMILY_ID attribute and returns the parsed
value in the local variable "id". If the reply does not carry that
attribute, the parsing loop never assigns "id" and the function returns
an indeterminate stack value, which the caller stores in self->fid and
uses for subsequent netlink requests.

Initialize "id" to 0 so a missing attribute yields a deterministic
(invalid) family ID instead of a garbage value.

Fixes: f595cf1242f3 ("selftests: Add nci suite")
Signed-off-by: Chaithanya Lagisetty <nagachaithanya9911@gmail.com>
---
 tools/testing/selftests/nci/nci_dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/nci/nci_dev.c b/tools/testing/selftests/nci/nci_dev.c
index 312f84ee0444..ed306ec23895 100644
--- a/tools/testing/selftests/nci/nci_dev.c
+++ b/tools/testing/selftests/nci/nci_dev.c
@@ -182,7 +182,7 @@ static int get_family_id(int sd, __u32 pid, __u32 *event_group)
 	} ans;
 	struct nlattr *na;
 	int resp_len;
-	__u16 id;
+	__u16 id = 0;
 	int len;
 	int rc;
 
-- 
2.43.0

On Tue, Sep 01, 2026 at 07:06:18AM +0000, Chaithanya Lagisetty wrote:
> get_family_id() walks the generic netlink CTRL_CMD_GETFAMILY reply
> looking for the CTRL_ATTR_FAMILY_ID attribute and returns the parsed
> value in the local variable "id". If the reply does not carry that
> attribute, the parsing loop never assigns "id" and the function returns
> an indeterminate stack value, which the caller stores in self->fid and
> uses for subsequent netlink requests.
> 
> Initialize "id" to 0 so a missing attribute yields a deterministic
> (invalid) family ID instead of a garbage value.
> 
> Fixes: f595cf1242f3 ("selftests: Add nci suite")
> Signed-off-by: Chaithanya Lagisetty <nagachaithanya9911@gmail.com>
> ---
>  tools/testing/selftests/nci/nci_dev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/nci/nci_dev.c b/tools/testing/selftests/nci/nci_dev.c
> index 312f84ee0444..ed306ec23895 100644
> --- a/tools/testing/selftests/nci/nci_dev.c
> +++ b/tools/testing/selftests/nci/nci_dev.c
> @@ -182,7 +182,7 @@ static int get_family_id(int sd, __u32 pid, __u32 *event_group)
>  	} ans;
>  	struct nlattr *na;
>  	int resp_len;
> -	__u16 id;
> +	__u16 id = 0;
>  	int len;
>  	int rc;
>  
> -- 
> 2.43.0
> 

Reviewed-by: Hangbin Liu <liuhangbin@kylinos.cn>