[PATCH net] tools: ynl: fix handling of multiple mcast groups

[PATCH net] tools: ynl: fix handling of multiple mcast groups

[Jakub Kicinski]

We never increment the group number iterator, so all groups
get recorded into index 0 of the mcast_groups[] array.

As a result YNL can only handle using the last group.
For example using the "netdev" sample on kernel with
page pool commands results in:

  $ ./samples/netdev
  YNL: Multicast group 'mgmt' not found

Most families have only one multicast group, so this hasn't
been noticed. Plus perhaps developers usually test the last
group which would have worked.

Fixes: 86878f14d71a ("tools: ynl: user space helpers")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: nicolas.dichtel@6wind.com
CC: willemb@google.com
---
 tools/net/ynl/lib/ynl.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/net/ynl/lib/ynl.c b/tools/net/ynl/lib/ynl.c
index c2ba72f68028..6bc95f07dc8f 100644
--- a/tools/net/ynl/lib/ynl.c
+++ b/tools/net/ynl/lib/ynl.c
@@ -585,6 +585,7 @@ ynl_get_family_info_mcast(struct ynl_sock *ys, const struct nlattr *mcasts)
 				ys->mcast_groups[i].name[GENL_NAMSIZ - 1] = 0;
 			}
 		}
+		i++;
 	}
 
 	return 0;
-- 
2.43.2

Re: [PATCH net] tools: ynl: fix handling of multiple mcast groups

[Donald Hunter]

Jakub Kicinski <kuba@kernel.org> writes:

> We never increment the group number iterator, so all groups
> get recorded into index 0 of the mcast_groups[] array.
>
> As a result YNL can only handle using the last group.
> For example using the "netdev" sample on kernel with
> page pool commands results in:
>
>   $ ./samples/netdev
>   YNL: Multicast group 'mgmt' not found
>
> Most families have only one multicast group, so this hasn't
> been noticed. Plus perhaps developers usually test the last
> group which would have worked.
>
> Fixes: 86878f14d71a ("tools: ynl: user space helpers")
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Reviewed-by: Donald Hunter <donald.hunter@gmail.com>

Re: [PATCH net] tools: ynl: fix handling of multiple mcast groups

[Nicolas Dichtel]

Le 26/02/2024 à 22:40, Jakub Kicinski a écrit :
> We never increment the group number iterator, so all groups
> get recorded into index 0 of the mcast_groups[] array.
> 
> As a result YNL can only handle using the last group.
> For example using the "netdev" sample on kernel with
> page pool commands results in:
> 
>   $ ./samples/netdev
>   YNL: Multicast group 'mgmt' not found
> 
> Most families have only one multicast group, so this hasn't
> been noticed. Plus perhaps developers usually test the last
> group which would have worked.
> 
> Fixes: 86878f14d71a ("tools: ynl: user space helpers")
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>

Re: [PATCH net] tools: ynl: fix handling of multiple mcast groups

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 26 Feb 2024 13:40:18 -0800 you wrote:
> We never increment the group number iterator, so all groups
> get recorded into index 0 of the mcast_groups[] array.
> 
> As a result YNL can only handle using the last group.
> For example using the "netdev" sample on kernel with
> page pool commands results in:
> 
> [...]

Here is the summary with links:
  - [net] tools: ynl: fix handling of multiple mcast groups
    https://git.kernel.org/netdev/net/c/b6c65eb20ffa

You are awesome, thank you!
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