mm: variable length argument support
Remove the arg+env limit of MAX_ARG_PAGES by copying the strings directly from
the old mm into the new mm.
We create the new mm before the binfmt code runs, and place the new stack at
the very top of the address space. Once the binfmt code runs and figures out
where the stack should be, we move it downwards.
It is a bit peculiar in that we have one task with two mm's, one of which is
inactive.
[a.p.zijlstra@chello.nl: limit stack size]
Signed-off-by: Ollie Wild <aaw@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <linux-arch@vger.kernel.org>
Cc: Hugh Dickins <hugh@veritas.com>
[bunk@stusta.de: unexport bprm_mm_init]
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index a27e42b..295cbaa 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -148,6 +148,7 @@
elf_addr_t *elf_info;
int ei_index = 0;
struct task_struct *tsk = current;
+ struct vm_area_struct *vma;
/*
* If this architecture has a platform capability string, copy it
@@ -234,6 +235,15 @@
sp = (elf_addr_t __user *)bprm->p;
#endif
+
+ /*
+ * Grow the stack manually; some architectures have a limit on how
+ * far ahead a user-space access may be in order to grow the stack.
+ */
+ vma = find_extend_vma(current->mm, bprm->p);
+ if (!vma)
+ return -EFAULT;
+
/* Now, let's put argc (and argv, envp if appropriate) on the stack */
if (__put_user(argc, sp++))
return -EFAULT;
@@ -254,8 +264,8 @@
size_t len;
if (__put_user((elf_addr_t)p, argv++))
return -EFAULT;
- len = strnlen_user((void __user *)p, PAGE_SIZE*MAX_ARG_PAGES);
- if (!len || len > PAGE_SIZE*MAX_ARG_PAGES)
+ len = strnlen_user((void __user *)p, MAX_ARG_STRLEN);
+ if (!len || len > MAX_ARG_STRLEN)
return 0;
p += len;
}
@@ -266,8 +276,8 @@
size_t len;
if (__put_user((elf_addr_t)p, envp++))
return -EFAULT;
- len = strnlen_user((void __user *)p, PAGE_SIZE*MAX_ARG_PAGES);
- if (!len || len > PAGE_SIZE*MAX_ARG_PAGES)
+ len = strnlen_user((void __user *)p, MAX_ARG_STRLEN);
+ if (!len || len > MAX_ARG_STRLEN)
return 0;
p += len;
}
@@ -826,10 +836,6 @@
}
/* OK, This is the point of no return */
- current->mm->start_data = 0;
- current->mm->end_data = 0;
- current->mm->end_code = 0;
- current->mm->mmap = NULL;
current->flags &= ~PF_FORKNOEXEC;
current->mm->def_flags = def_flags;
@@ -1051,9 +1057,13 @@
compute_creds(bprm);
current->flags &= ~PF_FORKNOEXEC;
- create_elf_tables(bprm, &loc->elf_ex,
+ retval = create_elf_tables(bprm, &loc->elf_ex,
(interpreter_type == INTERPRETER_AOUT),
load_addr, interp_load_addr);
+ if (retval < 0) {
+ send_sig(SIGKILL, current, 0);
+ goto out;
+ }
/* N.B. passed_fileno might not be initialized? */
if (interpreter_type == INTERPRETER_AOUT)
current->mm->arg_start += strlen(passed_fileno) + 1;