[PATCH] Fix ifinfo_link_with_port race condition with newlink

[Pavel Shirshov]

When a member port is enslaved into a port channel
immediately after the port channel was created,
it is possible to get member port ifinfo structure
not initialized for the member port because of a race
condition.

The race condition here occurs because order of
following events is not strict:
 - adding the member port to the port channel;
 - creating ifinfo structure for the member port.

The error message "Failed to link port with ifinfo" is
thrown when a member port is tried to be added to the
team handler's port list before ifinfo structure was
initialized.

To fix this situation ifinfo_find_create() is used
to search member ports ifinfo structure in
ifinfo_link_with_port().

Signed-off-by: Shuotian Cheng 
Signed-off-by: Pavel Shirshov 
---
 libteam/ifinfo.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libteam/ifinfo.c b/libteam/ifinfo.c
index 46d56a2..a15788b 100644
--- a/libteam/ifinfo.c
+++ b/libteam/ifinfo.c
@@ -453,7 +453,10 @@ int ifinfo_link_with_port(struct team_handle *th, uint32_t ifindex,
 {
    struct team_ifinfo *ifinfo;

-	ifinfo = ifinfo_find(th, ifindex);
+	if (port)
+		ifinfo = ifinfo_find_create(th, ifindex);
+	else
+		ifinfo = ifinfo_find(th, ifindex);
    if (!ifinfo)
    	return -ENOENT;
    if (ifinfo->linked)

[Jiri Pirko]

Fri, Apr 03, 2020 at 02:24:05AM CEST, [e-mail] wrote:
> When a member port is enslaved into a port channel
> immediately after the port channel was created,
> it is possible to get member port ifinfo structure
> not initialized for the member port because of a race
> condition.
>
> The race condition here occurs because order of
> following events is not strict:
> adding the member port to the port channel;
> creating ifinfo structure for the member port.
>
> The error message "Failed to link port with ifinfo" is
> thrown when a member port is tried to be added to the
> team handler's port list before ifinfo structure was
> initialized.
>
> To fix this situation ifinfo_find_create() is used
> to search member ports ifinfo structure in
> ifinfo_link_with_port().
>
> Signed-off-by: Shuotian Cheng 
> Signed-off-by: Pavel Shirshov

Applied, thanks!