Subject: Re: [PATCH net] tipc: fix duplicate publication key in tipc_service_insert_publ()

From: Simon Horman <[email-masked]>
Date: Mon, 23 Feb 2026 17:24:59 +0000

On Fri, Feb 20, 2026 at 05:05:41AM +0000, Tung Nguyen wrote:
> TIPC uses named table to store TIPC services represented by type and
> instance. Each time an application calls TIPC API bind() to bind a
> type/instance to a socket, an entry is created and inserted into the
> named table. It looks like this:
> 
> named table:
> key1, entry1 (type, instance ...)
> key2, entry2 (type, instance ...)
> 
> In the above table, each entry represents a route for sending data
> from one socket to the other. For all publications originated from
> the same node, the key is UNIQUE to identify each entry.
> It is calculated by this formula:
> key = socket portid + number of bindings + 1 (1)
> 
> where:
>  - socket portid: unique and calculated by using linux kernel function
>                   get_random_u32_below(). So, the value is randomized.
>  - number of bindings: the number of times a type/instance pair is bound
>                        to a socket. This number is linearly increased,
>                        starting from 0.
> 
> While the socket portid is unique and randomized by linux kernel, the
> linear increment of "number of bindings" in formula (1) makes "key" not
> unique anymore. For example:
> - Socket 1 is created with its associated port number 20062001. Type 1000,
> instance 1 is bound to socket 1:
> key1: 20062001 + 0 + 1 = 20062002
> 
> Then, bind() is called a second time on Socket 1 to by the same type 1000,
> instance 1:
> key2: 20062001 + 1 + 1 = 20062003
> 
> Named table:
> key1 (20062002), entry1 (1000, 1 ...)
> key2 (20062003), entry2 (1000, 1 ...)
> 
> - Socket 2 is created with its associated port number 20062002. Type 1000,
> instance 1 is bound to socket 2:
> key3: 20062002 + 0 + 1 = 20062003
> 
> TIPC looks up the named table and finds out that key2 with the same value
> already exists and rejects the insertion into the named table.
> This leads to failure of bind() call from application on Socket 2 with error
> message EINVAL "Invalid argument".
> 
> This commit fixes this issue by adding more port id checking to make sure
> that the key is unique to publications originated from the same port id
> and node.
> 
> Fixes: 218527fe27ad ("tipc: replace name table service range array with rb tree")
> Signed-off-by: Tung Nguyen <[email-masked]>

Thanks.

My understanding is that ->ref functions as the portid.
And if so, this makes sense to me.

Reviewed-by: Simon Horman <[email-masked]>