clarify API doc for osmo_pfcp_endpoint_tx()

I recently discovered some use-after-free in osmo-upf by wrong API usage
of osmo_pfcp_endpoint_tx(). Highlight this pitfall in API doc.

Change-Id: I637e7bb5d1296b5ad8db8ab0b8151fdbb9e7be03
This commit is contained in:
Neels Hofmeyr 2023-02-09 00:06:41 +01:00 committed by neels
parent 6df7905736
commit c518e3fa06
1 changed files with 6 additions and 1 deletions

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@ -326,7 +326,12 @@ static int osmo_pfcp_endpoint_retrans_queue_add(struct osmo_pfcp_endpoint *endpo
* Store the message in the local message queue for possible retransmissions.
* On success, return zero, and pass ownership of m to ep. ep deallocates m when all retransmissions are done / a reply
* has been received.
* On error, return nonzero, and immediately deallocate m. */
* On error, return nonzero, and immediately deallocate m.
*
* WARNING: Do not access the osmo_pfcp_msg m after calling this function! In most cases, m will still remain allocated,
* and accessing it will work, but especially when an error occurs, m will be deallocated immediately. Hence, you will
* see no problem during normal successful operation, but your program will crash with use-after-free on any error!
*/
int osmo_pfcp_endpoint_tx(struct osmo_pfcp_endpoint *ep, struct osmo_pfcp_msg *m)
{
struct osmo_pfcp_ie_node_id *node_id;