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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2022-06-03 16:03:05 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-06-03 16:03:05 -0700 |
| commit | 1ec6574a3c0a22c130c08e8c36c825cb87d68f8e (patch) | |
| tree | 1f064c4a4965b9b0dd213456649b23e066d54bea /init | |
| parent | 1888e9b4bb78c88514b24ecafa9e4e4faf761747 (diff) | |
| parent | b3f9916d81e8ffb21cbe7abccf63f86a5a1d598a (diff) | |
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 'init')
| -rw-r--r-- | init/initramfs.c | 2 | ||||
| -rw-r--r-- | init/main.c | 2 |
2 files changed, 3 insertions, 1 deletions
diff --git a/init/initramfs.c b/init/initramfs.c index dc84cf756cea..18229cfe8906 100644 --- a/init/initramfs.c +++ b/init/initramfs.c @@ -15,6 +15,7 @@ #include <linux/mm.h> #include <linux/namei.h> #include <linux/init_syscalls.h> +#include <linux/task_work.h> #include <linux/umh.h> static __initdata bool csum_present; @@ -727,6 +728,7 @@ done: initrd_end = 0; flush_delayed_fput(); + task_work_run(); } static ASYNC_DOMAIN_EXCLUSIVE(initramfs_domain); diff --git a/init/main.c b/init/main.c index 02eb533018f6..0ee39cdcfcac 100644 --- a/init/main.c +++ b/init/main.c @@ -688,7 +688,7 @@ noinline void __ref rest_init(void) * the init task will end up wanting to create kthreads, which, if * we schedule it before we create kthreadd, will OOPS. */ - pid = kernel_thread(kernel_init, NULL, CLONE_FS); + pid = user_mode_thread(kernel_init, NULL, CLONE_FS); /* * Pin init on the boot CPU. Task migration is not properly working * until sched_init_smp() has been run. It will set the allowed |