[PATCH 1/2] taskstats: set version in TGID exit notifications

[Yiyang Chen]

delay accounting started populating taskstats records with a valid
version field via fill_pid() and fill_tgid().

Later, commit ad4ecbcba728 ("[PATCH] delay accounting taskstats
interface send tgid once") changed the TGID exit path to send the
cached signal->stats aggregate directly instead of building the outgoing
record through fill_tgid(). Unlike fill_tgid(), fill_tgid_exit() only
accumulates accounting data and never initializes stats->version.

As a result, TGID exit notifications can reach userspace with
version == 0 even though PID exit notifications and
TASKSTATS_CMD_GET replies carry a valid taskstats version.

Set stats->version = TASKSTATS_VERSION after copying the cached TGID
aggregate into the outgoing netlink payload so all taskstats records are
self-describing again.

Fixes: ad4ecbcba728 ("[PATCH] delay accounting taskstats interface send tgid once")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Yiyang Chen <cyyzero16@xxxxxxxxx>
---
 kernel/taskstats.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index 0cd680ccc7e5..73bd6a6a7893 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -649,6 +649,7 @@ void taskstats_exit(struct task_struct *tsk, int group_dead)
 		goto err;
 
 	memcpy(stats, tsk->signal->stats, sizeof(*stats));
+	stats->version = TASKSTATS_VERSION;
 
 send:
 	send_cpu_listeners(rep_skb, listeners);
-- 
2.43.0