The patch titled
pids: improve get_task_pid() to fix the unsafe sys_wait4()->task_pgrp()
has been added to the -mm tree. Its filename is
pids-improve-get_task_pid-to-fix-the-unsafe-sys_wait4-task_pgrp.patch
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------------------------------------------------------
Subject: pids: improve get_task_pid() to fix the unsafe sys_wait4()->task_pgrp()
From: Oleg Nesterov <oleg@xxxxxxxxxx>
sys_wait4() does get_pid(task_pgrp(current)), this is not safe. We can
add rcu lock/unlock around, but we already have get_task_pid() which can
be improved to handle the special pids in more reliable manner.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Louis Rilling <Louis.Rilling@xxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
Cc: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/exit.c | 2 +-
kernel/pid.c | 2 ++
2 files changed, 3 insertions(+), 1 deletion(-)
diff -puN kernel/exit.c~pids-improve-get_task_pid-to-fix-the-unsafe-sys_wait4-task_pgrp kernel/exit.c
--- a/kernel/exit.c~pids-improve-get_task_pid-to-fix-the-unsafe-sys_wait4-task_pgrp
+++ a/kernel/exit.c
@@ -1819,7 +1819,7 @@ SYSCALL_DEFINE4(wait4, pid_t, upid, int
pid = find_get_pid(-upid);
} else if (upid == 0) {
type = PIDTYPE_PGID;
- pid = get_pid(task_pgrp(current));
+ pid = get_task_pid(current, PIDTYPE_PGID);
} else /* upid > 0 */ {
type = PIDTYPE_PID;
pid = find_get_pid(upid);
diff -puN kernel/pid.c~pids-improve-get_task_pid-to-fix-the-unsafe-sys_wait4-task_pgrp kernel/pid.c
--- a/kernel/pid.c~pids-improve-get_task_pid-to-fix-the-unsafe-sys_wait4-task_pgrp
+++ a/kernel/pid.c
@@ -403,6 +403,8 @@ struct pid *get_task_pid(struct task_str
{
struct pid *pid;
rcu_read_lock();
+ if (type != PIDTYPE_PID)
+ task = task->group_leader;
pid = get_pid(task->pids[type].pid);
rcu_read_unlock();
return pid;
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
getrusage-fill-ru_maxrss-value.patch
pids-document-task_pgrp-task_session-is-not-safe-without-tasklist-rcu.patch
pids-document-task_pgrp-task_session-is-not-safe-without-tasklist-rcu-fix.patch
pids-improve-get_task_pid-to-fix-the-unsafe-sys_wait4-task_pgrp.patch
pids-refactor-vnr-nr_ns-helpers-to-make-them-safe.patch
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