| Date | Tue, 16 Oct 2018 17:10:29 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [RFC PATCH for 4.21 06/16] cpu_opv: Provide cpu_opv system call (v8) |
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Hi Mathieu,
On (10/10/18 15:19), Mathieu Desnoyers wrote: [..] > +SYSCALL_DEFINE4(cpu_opv, struct cpu_op __user *, ucpuopv, int, cpuopcnt, > + int, cpu, int, flags) > +{ [..] > +again: > + ret = cpu_opv_pin_pages(cpuopv, cpuopcnt, &vaddr_ptrs); > + if (ret) > + goto end; > + ret = do_cpu_opv(cpuopv, cpuopcnt, &vaddr_ptrs, cpu); > + if (ret == -EAGAIN) > + retry = true; > +end: > + for (i = 0; i < vaddr_ptrs.nr_vaddr; i++) { > + struct vaddr *vaddr = &vaddr_ptrs.addr[i]; > + int j; > + > + vm_unmap_user_ram((void *)vaddr->mem, vaddr->nr_pages);
A dumb question.
Both vm_unmap_user_ram() and vm_map_user_ram() can BUG_ON(). So this is userspace -> syscall -> cpu_opv() -> vm_unmap_user_ram() -> BUG_ON()
Any chance someone can exploit it?
-ss
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