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| author | Eric W. Biederman <ebiederm@xmission.com> | 2021-12-23 01:57:50 +0300 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2021-12-23 01:57:50 +0300 |
| commit | 00580f03af5eb2a527875b4a80a5effd95bda2fa (patch) | |
| tree | 43cf743e630c66d1c711b67c179e2bbe03025ba9 | |
| parent | dd621ee0cf8eb32445c8f5f26d3b7555953071d8 (diff) | |
| download | linux-00580f03af5eb2a527875b4a80a5effd95bda2fa.tar.xz | |
kthread: Never put_user the set_child_tid address
Kernel threads abuse set_child_tid. Historically that has been fine
as set_child_tid was initialized after the kernel thread had been
forked. Unfortunately storing struct kthread in set_child_tid after
the thread is running makes struct kthread being unusable for storing
result codes of the thread.
When set_child_tid is set to struct kthread during fork that results
in schedule_tail writing the thread id to the beggining of struct
kthread (if put_user does not realize it is a kernel address).
Solve this by skipping the put_user for all kthreads.
Reported-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lkml.kernel.org/r/YcNsG0Lp94V13whH@archlinux-ax161
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| -rw-r--r-- | kernel/sched/core.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index ee222b89c692..d8adbea77be1 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4908,7 +4908,7 @@ asmlinkage __visible void schedule_tail(struct task_struct *prev) finish_task_switch(prev); preempt_enable(); - if (current->set_child_tid) + if (!(current->flags & PF_KTHREAD) && current->set_child_tid) put_user(task_pid_vnr(current), current->set_child_tid); calculate_sigpending(); |