* [PATCH] fork: fix copy_process(CLONE_PARENT) race with the exiting ->real_parent
@ 2020-11-07 6:47 Eddy Wu
2020-11-08 19:19 ` Linus Torvalds
0 siblings, 1 reply; 2+ messages in thread
From: Eddy Wu @ 2020-11-07 6:47 UTC (permalink / raw)
To: oleg; +Cc: security, linux-kernel, eddy_wu
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@trendmicro.com>
---
kernel/fork.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index da8d360fb032..7abda2a888a9 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2142,14 +2142,9 @@ static __latent_entropy struct task_struct *copy_process(
/* 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;
}
@@ -2193,9 +2188,14 @@ static __latent_entropy struct task_struct *copy_process(
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);
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] fork: fix copy_process(CLONE_PARENT) race with the exiting ->real_parent
2020-11-07 6:47 [PATCH] fork: fix copy_process(CLONE_PARENT) race with the exiting ->real_parent Eddy Wu
@ 2020-11-08 19:19 ` Linus Torvalds
0 siblings, 0 replies; 2+ messages in thread
From: Linus Torvalds @ 2020-11-08 19:19 UTC (permalink / raw)
To: Eddy Wu
Cc: Oleg Nesterov, Security Officers, Linux Kernel Mailing List, eddy_wu
On Fri, Nov 6, 2020 at 10:47 PM Eddy Wu <itseddy0402@gmail.com> wrote:
>
> 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.
Applied. Thanks,
Linus
^ permalink raw reply [flat|nested] 2+ messages in thread
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