From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> commit 1b5a42d9c85f0e731f01c8d1129001fd8531a8a0 upstream. In the function bacct_add_task the code reading task->exit_code was introduced in commit f3cef7a99469 ("[PATCH] csa: basic accounting over taskstats"), and it is not entirely clear what the taskstats interface is trying to return as only returning the exit_code of the first task in a process doesn't make a lot of sense. As best as I can figure the intent is to return task->exit_code after a task exits. The field is returned with per task fields, so the exit_code of the entire process is not wanted. Only the value of the first task is returned so this is not a useful way to get the per task ptrace stop code. The ordinary case of returning this value is returning after a task exits, which also precludes use for getting a ptrace value. It is common to for the first task of a process to also be the last task of a process so this field may have done something reasonable by accident in testing. Make ac_exitcode a reliable per task value by always returning it for every exited task. Setting ac_exitcode in a sensible mannter makes it possible to continue to provide this value going forward. Cc: Balbir Singh <bsingharora@xxxxxxxxx> Fixes: f3cef7a99469 ("[PATCH] csa: basic accounting over taskstats") Link: https://lkml.kernel.org/r/20220103213312.9144-5-ebiederm@xxxxxxxxxxxx Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> [sudip: adjust context] Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/tsacct.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/kernel/tsacct.c +++ b/kernel/tsacct.c @@ -44,11 +44,10 @@ void bacct_add_tsk(struct user_namespace /* Convert to seconds for btime */ do_div(delta, USEC_PER_SEC); stats->ac_btime = get_seconds() - delta; - if (thread_group_leader(tsk)) { + if (tsk->flags & PF_EXITING) stats->ac_exitcode = tsk->exit_code; - if (tsk->flags & PF_FORKNOEXEC) - stats->ac_flag |= AFORK; - } + if (thread_group_leader(tsk) && (tsk->flags & PF_FORKNOEXEC)) + stats->ac_flag |= AFORK; if (tsk->flags & PF_SUPERPRIV) stats->ac_flag |= ASU; if (tsk->flags & PF_DUMPCORE)