sctp: sctp_sock_filter(): avoid list_entry() on possibly empty list

stable inclusion
from stable-v5.10.169
commit 747a17e25aecb4ea8a66427058e0d2d2a25046ad
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7V9QX

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=747a17e25aecb4ea8a66427058e0d2d2a25046ad



----------------------------------------------------

commit a1221703 upstream.

Use list_is_first() to check whether tsp->asoc matches the first
element of ep->asocs, as the list is not guaranteed to have an entry.

Fixes: 8f840e47 ("sctp: add the sctp_diag.c file")
Signed-off-by: Pietro Borrello <borrello@diag.uniroma1.it>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://lore.kernel.org/r/20230208-sctp-filter-v2-1-6e1f4017f326@diag.uniroma1.it


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: zhaoxiaoqiang11 <zhaoxiaoqiang11@jd.com>