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author | Linus Torvalds <torvalds@linux-foundation.org> | 2022-06-03 16:03:05 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-06-03 16:03:05 -0700 |
commit | 1ec6574a3c0a22c130c08e8c36c825cb87d68f8e (patch) | |
tree | 1f064c4a4965b9b0dd213456649b23e066d54bea /arch/s390/kernel | |
parent | 1888e9b4bb78c88514b24ecafa9e4e4faf761747 (diff) | |
parent | b3f9916d81e8ffb21cbe7abccf63f86a5a1d598a (diff) | |
download | linux-1ec6574a3c0a22c130c08e8c36c825cb87d68f8e.tar.gz linux-1ec6574a3c0a22c130c08e8c36c825cb87d68f8e.tar.bz2 linux-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/s390/kernel')
-rw-r--r-- | arch/s390/kernel/process.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c index 71d86f73b02c..89949b9f3cf8 100644 --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -94,9 +94,11 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) return 0; } -int copy_thread(unsigned long clone_flags, unsigned long new_stackp, - 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 new_stackp = args->stack; + unsigned long tls = args->tls; struct fake_frame { struct stack_frame sf; @@ -130,15 +132,15 @@ int copy_thread(unsigned long clone_flags, unsigned long new_stackp, frame->sf.gprs[9] = (unsigned long)frame; /* Store access registers to kernel stack of new process. */ - if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) { + if (unlikely(args->fn)) { /* kernel thread */ memset(&frame->childregs, 0, sizeof(struct pt_regs)); frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK; frame->childregs.psw.addr = (unsigned long)__ret_from_fork; - frame->childregs.gprs[9] = new_stackp; /* function */ - frame->childregs.gprs[10] = arg; + frame->childregs.gprs[9] = (unsigned long)args->fn; + frame->childregs.gprs[10] = (unsigned long)args->fn_arg; frame->childregs.orig_gpr2 = -1; frame->childregs.last_break = 1; return 0; |