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authorLinus Torvalds <torvalds@linux-foundation.org>2022-06-04 02:03:05 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-06-04 02:03:05 +0300
commit1ec6574a3c0a22c130c08e8c36c825cb87d68f8e (patch)
tree1f064c4a4965b9b0dd213456649b23e066d54bea /include
parent1888e9b4bb78c88514b24ecafa9e4e4faf761747 (diff)
parentb3f9916d81e8ffb21cbe7abccf63f86a5a1d598a (diff)
downloadlinux-1ec6574a3c0a22c130c08e8c36c825cb87d68f8e.tar.xz
Merge tag 'kthread-cleanups-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull kthread updates from Eric Biederman: "This updates init and user mode helper tasks to be ordinary user mode tasks. Commit 40966e316f86 ("kthread: Ensure struct kthread is present for all kthreads") caused init and the user mode helper threads that call kernel_execve to have struct kthread allocated for them. This struct kthread going away during execve in turned made a use after free of struct kthread possible. Here, commit 343f4c49f243 ("kthread: Don't allocate kthread_struct for init and umh") is enough to fix the use after free and is simple enough to be backportable. The rest of the changes pass struct kernel_clone_args to clean things up and cause the code to make sense. In making init and the user mode helpers tasks purely user mode tasks I ran into two complications. The function task_tick_numa was detecting tasks without an mm by testing for the presence of PF_KTHREAD. The initramfs code in populate_initrd_image was using flush_delayed_fput to ensuere the closing of all it's file descriptors was complete, and flush_delayed_fput does not work in a userspace thread. I have looked and looked and more complications and in my code review I have not found any, and neither has anyone else with the code sitting in linux-next" * tag 'kthread-cleanups-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: sched: Update task_tick_numa to ignore tasks without an mm fork: Stop allowing kthreads to call execve fork: Explicitly set PF_KTHREAD init: Deal with the init process being a user mode process fork: Generalize PF_IO_WORKER handling fork: Explicity test for idle tasks in copy_thread fork: Pass struct kernel_clone_args into copy_thread kthread: Don't allocate kthread_struct for init and umh
Diffstat (limited to 'include')
-rw-r--r--include/linux/sched/task.h8
1 files changed, 6 insertions, 2 deletions
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 719c9a6cac8d..505aaf9fe477 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -32,6 +32,10 @@ struct kernel_clone_args {
size_t set_tid_size;
int cgroup;
int io_thread;
+ int kthread;
+ int idle;
+ int (*fn)(void *);
+ void *fn_arg;
struct cgroup *cgrp;
struct css_set *cset;
};
@@ -67,8 +71,7 @@ extern void fork_init(void);
extern void release_task(struct task_struct * p);
-extern int copy_thread(unsigned long, unsigned long, unsigned long,
- struct task_struct *, unsigned long);
+extern int copy_thread(struct task_struct *, const struct kernel_clone_args *);
extern void flush_thread(void);
@@ -89,6 +92,7 @@ struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
struct task_struct *fork_idle(int);
struct mm_struct *copy_init_mm(void);
extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
+extern pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags);
extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
int kernel_wait(pid_t pid, int *stat);