This is a note to let you know that I've just added the patch titled
fork: fix copy_process(CLONE_PARENT) race with the exiting ->real_parent
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fork-fix-copy_process-clone_parent-race-with-the-exiting-real_parent.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b4e00444cab4c3f3fec876dc0cccc8cbb0d1a948 Mon Sep 17 00:00:00 2001
From: Eddy Wu <itseddy0402@xxxxxxxxx>
Date: Sat, 7 Nov 2020 14:47:22 +0800
Subject: fork: fix copy_process(CLONE_PARENT) race with the exiting ->real_parent
From: Eddy Wu <itseddy0402@xxxxxxxxx>
commit b4e00444cab4c3f3fec876dc0cccc8cbb0d1a948 upstream.
current->group_leader->exit_signal may change during copy_process() if
current->real_parent exits.
Move the assignment inside tasklist_lock to avoid the race.
Signed-off-by: Eddy Wu <eddy_wu@xxxxxxxxxxxxxx>
Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/fork.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2100,14 +2100,9 @@ static __latent_entropy struct task_stru
/* ok, now we should be set up.. */
p->pid = pid_nr(pid);
if (clone_flags & CLONE_THREAD) {
- p->exit_signal = -1;
p->group_leader = current->group_leader;
p->tgid = current->tgid;
} else {
- if (clone_flags & CLONE_PARENT)
- p->exit_signal = current->group_leader->exit_signal;
- else
- p->exit_signal = args->exit_signal;
p->group_leader = p;
p->tgid = p->pid;
}
@@ -2152,9 +2147,14 @@ static __latent_entropy struct task_stru
if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
p->real_parent = current->real_parent;
p->parent_exec_id = current->parent_exec_id;
+ if (clone_flags & CLONE_THREAD)
+ p->exit_signal = -1;
+ else
+ p->exit_signal = current->group_leader->exit_signal;
} else {
p->real_parent = current;
p->parent_exec_id = current->self_exec_id;
+ p->exit_signal = args->exit_signal;
}
klp_copy_process(p);
Patches currently in stable-queue which might be from itseddy0402@xxxxxxxxx are
queue-5.4/fork-fix-copy_process-clone_parent-race-with-the-exiting-real_parent.patch
