exec: create initial stack independent of PAGE_SIZE

[safe/jmp/linux-2.6] / fs / exec.c

diff --git a/fs/exec.c b/fs/exec.c
index 0790a10..da2b31d 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -195,7 +195,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
                 *    to work from.
                 */
                rlim = current->signal->rlim;
-               if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
+               if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
                        put_page(page);
                        return NULL;
                }
@@ -246,6 +246,7 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
        vma->vm_start = vma->vm_end - PAGE_SIZE;
        vma->vm_flags = VM_STACK_FLAGS;
        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+       INIT_LIST_HEAD(&vma->anon_vma_chain);
        err = insert_vm_struct(mm, vma);
        if (err)
                goto err;
@@ -516,7 +517,8 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
        /*
         * cover the whole range: [new_start, old_end)
         */
-       vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
+       if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
+               return -ENOMEM;
 
        /*
         * move the page tables downwards, on failure we rely on
@@ -547,15 +549,13 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
        tlb_finish_mmu(tlb, new_end, old_end);
 
        /*
-        * shrink the vma to just the new range.
+        * Shrink the vma to just the new range.  Always succeeds.
         */
        vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 
        return 0;
 }
 
-#define EXTRA_STACK_VM_PAGES   20      /* random */
-
 /*
  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
  * the stack is optionally relocated, and some extra space is added.
@@ -571,10 +571,13 @@ int setup_arg_pages(struct linux_binprm *bprm,
        struct vm_area_struct *prev = NULL;
        unsigned long vm_flags;
        unsigned long stack_base;
+       unsigned long stack_size;
+       unsigned long stack_expand;
+       unsigned long rlim_stack;
 
 #ifdef CONFIG_STACK_GROWSUP
        /* Limit stack size to 1GB */
-       stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
+       stack_base = rlimit_max(RLIMIT_STACK);
        if (stack_base > (1 << 30))
                stack_base = 1 << 30;
 
@@ -627,10 +630,23 @@ int setup_arg_pages(struct linux_binprm *bprm,
                        goto out_unlock;
        }
 
+       stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
+       stack_size = vma->vm_end - vma->vm_start;
+       /*
+        * Align this down to a page boundary as expand_stack
+        * will align it up.
+        */
+       rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
 #ifdef CONFIG_STACK_GROWSUP
-       stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
+       if (stack_size + stack_expand > rlim_stack)
+               stack_base = vma->vm_start + rlim_stack;
+       else
+               stack_base = vma->vm_end + stack_expand;
 #else
-       stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
+       if (stack_size + stack_expand > rlim_stack)
+               stack_base = vma->vm_end - rlim_stack;
+       else
+               stack_base = vma->vm_start - stack_expand;
 #endif
        ret = expand_stack(vma, stack_base);
        if (ret)
@@ -702,6 +718,7 @@ static int exec_mmap(struct mm_struct *mm)
        /* Notify parent that we're no longer interested in the old VM */
        tsk = current;
        old_mm = current->mm;
+       sync_mm_rss(tsk, old_mm);
        mm_release(tsk, old_mm);
 
        if (old_mm) {
@@ -1516,7 +1533,7 @@ static int format_corename(char *corename, long signr)
                        /* core limit size */
                        case 'c':
                                rc = snprintf(out_ptr, out_end - out_ptr,
-                                             "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
+                                             "%lu", rlimit(RLIMIT_CORE));
                                if (rc > out_end - out_ptr)
                                        goto out;
                                out_ptr += rc;
@@ -1781,7 +1798,7 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
        struct coredump_params cprm = {
                .signr = signr,
                .regs = regs,
-               .limit = current->signal->rlim[RLIMIT_CORE].rlim_cur,
+               .limit = rlimit(RLIMIT_CORE),
        };
 
        audit_core_dumps(signr);