While running pasta, we trigger the following assert:
ASSERTION FAILED in udp_at_sidx (udp_flow.c:35): flow->f.type == FLOW_UDP
in udp_at_sidx() in the following path:
902 void udp_sock_handler(const struct ctx *c, union epoll_ref ref,
903 uint32_t events, const struct timespec *now)
904 {
905 struct udp_flow *uflow = udp_at_sidx(ref.flowside);
The invalid sidx is comming from the epoll_ref provided by epoll_wait().
This assert follows the following error:
Couldn't connect flow socket: Permission denied
It appears that an error happens in udp_flow_sock() and the recently
created fd is not removed from the epoll_ctl() pool:
71 static int udp_flow_sock(const struct ctx *c,
72 struct udp_flow *uflow, unsigned sidei)
73 {
...
82 s = flowside_sock_l4(c, EPOLL_TYPE_UDP, pif, side, fref.data);
83 if (s < 0) {
84 flow_dbg_perror(uflow, "Couldn't open flow specific socket");
85 return s;
86 }
87
88 if (flowside_connect(c, s, pif, side) < 0) {
89 int rc = -errno;
90 flow_dbg_perror(uflow, "Couldn't connect flow socket");
91 return rc;
92 }
...
flowside_sock_l4() calls sock_l4_sa() that adds 's' to the epoll_ctl()
pool.
So to cleanly manage the error of flowside_connect() we need to remove
's' from the epoll_ctl() pool using epoll_del().
Link: https://github.com/containers/podman/issues/26073
Signed-off-by: Laurent Vivier