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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/arm64 | |
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 'arch/arm64')
-rw-r--r-- | arch/arm64/kernel/process.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 2f42123e059f..92bcc1768f0b 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -343,9 +343,11 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) asmlinkage void ret_from_fork(void) asm("ret_from_fork"); -int copy_thread(unsigned long clone_flags, unsigned long stack_start, - unsigned long stk_sz, 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 stack_start = args->stack; + unsigned long tls = args->tls; struct pt_regs *childregs = task_pt_regs(p); memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context)); @@ -361,7 +363,7 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start, ptrauth_thread_init_kernel(p); - if (likely(!(p->flags & (PF_KTHREAD | PF_IO_WORKER)))) { + if (likely(!args->fn)) { *childregs = *current_pt_regs(); childregs->regs[0] = 0; @@ -399,8 +401,8 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start, memset(childregs, 0, sizeof(struct pt_regs)); childregs->pstate = PSR_MODE_EL1h | PSR_IL_BIT; - p->thread.cpu_context.x19 = stack_start; - p->thread.cpu_context.x20 = stk_sz; + p->thread.cpu_context.x19 = (unsigned long)args->fn; + p->thread.cpu_context.x20 = (unsigned long)args->fn_arg; } p->thread.cpu_context.pc = (unsigned long)ret_from_fork; p->thread.cpu_context.sp = (unsigned long)childregs; |