diff options
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 /arch/x86/kernel/process.c | |
parent | 1888e9b4bb78c88514b24ecafa9e4e4faf761747 (diff) | |
parent | b3f9916d81e8ffb21cbe7abccf63f86a5a1d598a (diff) | |
download | linux-stable-1ec6574a3c0a22c130c08e8c36c825cb87d68f8e.tar.gz linux-stable-1ec6574a3c0a22c130c08e8c36c825cb87d68f8e.tar.bz2 linux-stable-1ec6574a3c0a22c130c08e8c36c825cb87d68f8e.zip |
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 'arch/x86/kernel/process.c')
-rw-r--r-- | arch/x86/kernel/process.c | 18 |
1 files changed, 10 insertions, 8 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 58fb48d3004f..9b2772b7e1f3 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -131,9 +131,11 @@ static int set_new_tls(struct task_struct *p, unsigned long tls) return do_set_thread_area_64(p, ARCH_SET_FS, tls); } -int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, - struct task_struct *p, unsigned long tls) +int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) { + unsigned long clone_flags = args->flags; + unsigned long sp = args->stack; + unsigned long tls = args->tls; struct inactive_task_frame *frame; struct fork_frame *fork_frame; struct pt_regs *childregs; @@ -171,13 +173,13 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, frame->flags = X86_EFLAGS_FIXED; #endif - fpu_clone(p, clone_flags); + fpu_clone(p, clone_flags, args->fn); /* Kernel thread ? */ if (unlikely(p->flags & PF_KTHREAD)) { p->thread.pkru = pkru_get_init_value(); memset(childregs, 0, sizeof(struct pt_regs)); - kthread_frame_init(frame, sp, arg); + kthread_frame_init(frame, args->fn, args->fn_arg); return 0; } @@ -193,10 +195,10 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, if (sp) childregs->sp = sp; - if (unlikely(p->flags & PF_IO_WORKER)) { + if (unlikely(args->fn)) { /* - * An IO thread is a user space thread, but it doesn't - * return to ret_after_fork(). + * A user space thread, but it doesn't return to + * ret_after_fork(). * * In order to indicate that to tools like gdb, * we reset the stack and instruction pointers. @@ -206,7 +208,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, */ childregs->sp = 0; childregs->ip = 0; - kthread_frame_init(frame, sp, arg); + kthread_frame_init(frame, args->fn, args->fn_arg); return 0; } |