if (!pte)
goto out_pte;
- /*
- * There's an interaction between the skas0 stub pages, stack
- * randomization, and the BUG at the end of exit_mmap. exit_mmap
- * checks that the number of page tables freed is the same as had
- * been allocated. If the stack is on the last page table page,
- * then the stack pte page will be freed, and if not, it won't. To
- * avoid having to know where the stack is, or if the process mapped
- * something at the top of its address space for some other reason,
- * we set TASK_SIZE to end at the start of the last page table.
- * This keeps exit_mmap off the last page, but introduces a leak
- * of that page. So, we hang onto it here and free it in
- * destroy_context_skas.
- */
-
- mm->context.last_page_table = pmd_page_vaddr(*pmd);
-#ifdef CONFIG_3_LEVEL_PGTABLES
- mm->context.last_pmd = (unsigned long) __va(pud_val(*pud));
-#endif
-
*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
*pte = pte_mkread(*pte);
return 0;
out_pmd:
- pud_free(pud);
+ pud_free(mm, pud);
out_pte:
- pmd_free(pmd);
+ pmd_free(mm, pmd);
out:
return -ENOMEM;
}
stack = get_zeroed_page(GFP_KERNEL);
if (stack == 0)
goto out;
-
- /*
- * This zeros the entry that pgd_alloc didn't, needed since
- * we are about to reinitialize it, and want mm.nr_ptes to
- * be accurate.
- */
- mm->pgd[USER_PTRS_PER_PGD] = __pgd(0);
-
- ret = init_stub_pte(mm, STUB_CODE,
- (unsigned long) &__syscall_stub_start);
- if (ret)
- goto out_free;
-
- ret = init_stub_pte(mm, STUB_DATA, stack);
- if (ret)
- goto out_free;
-
- mm->nr_ptes--;
}
to_mm->id.stack = stack;
to_mm->id.u.pid = copy_context_skas0(stack,
from_mm->id.u.pid);
else to_mm->id.u.pid = start_userspace(stack);
+
+ if (to_mm->id.u.pid < 0) {
+ ret = to_mm->id.u.pid;
+ goto out_free;
+ }
}
ret = init_new_ldt(to_mm, from_mm);
return ret;
}
+void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
+{
+ struct page **pages;
+ int err, ret;
+
+ if (!skas_needs_stub)
+ return;
+
+ ret = init_stub_pte(mm, STUB_CODE,
+ (unsigned long) &__syscall_stub_start);
+ if (ret)
+ goto out;
+
+ ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
+ if (ret)
+ goto out;
+
+ pages = kmalloc(2 * sizeof(struct page *), GFP_KERNEL);
+ if (pages == NULL) {
+ printk(KERN_ERR "arch_dup_mmap failed to allocate 2 page "
+ "pointers\n");
+ goto out;
+ }
+
+ pages[0] = virt_to_page(&__syscall_stub_start);
+ pages[1] = virt_to_page(mm->context.id.stack);
+
+ /* dup_mmap already holds mmap_sem */
+ err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
+ VM_READ | VM_MAYREAD | VM_EXEC |
+ VM_MAYEXEC | VM_DONTCOPY, pages);
+ if (err) {
+ printk(KERN_ERR "install_special_mapping returned %d\n", err);
+ goto out_free;
+ }
+ return;
+
+out_free:
+ kfree(pages);
+out:
+ force_sigsegv(SIGSEGV, current);
+}
+
+void arch_exit_mmap(struct mm_struct *mm)
+{
+ pte_t *pte;
+
+ pte = virt_to_pte(mm, STUB_CODE);
+ if (pte != NULL)
+ pte_clear(mm, STUB_CODE, pte);
+
+ pte = virt_to_pte(mm, STUB_DATA);
+ if (pte == NULL)
+ return;
+
+ pte_clear(mm, STUB_DATA, pte);
+}
+
void destroy_context(struct mm_struct *mm)
{
struct mm_context *mmu = &mm->context;
if (proc_mm)
os_close_file(mmu->id.u.mm_fd);
- else
+ else {
+ /*
+ * If init_new_context wasn't called, this will be
+ * zero, resulting in a kill(0), which will result in the
+ * whole UML suddenly dying. Also, cover negative and
+ * 1 cases, since they shouldn't happen either.
+ */
+ if (mmu->id.u.pid < 2) {
+ printk(KERN_ERR "corrupt mm_context - pid = %d\n",
+ mmu->id.u.pid);
+ return;
+ }
os_kill_ptraced_process(mmu->id.u.pid, 1);
+ }
- if (!proc_mm || !ptrace_faultinfo) {
+ if (skas_needs_stub)
free_page(mmu->id.stack);
- pte_lock_deinit(virt_to_page(mmu->last_page_table));
- pte_free_kernel((pte_t *) mmu->last_page_table);
- dec_zone_page_state(virt_to_page(mmu->last_page_table), NR_PAGETABLE);
-#ifdef CONFIG_3_LEVEL_PGTABLES
- pmd_free((pmd_t *) mmu->last_pmd);
-#endif
- }
free_ldt(mmu);
}
git.openpandora.org / pandora-kernel.git / blobdiff