releases/2.6.36.2/exec-copy-and-paste-the-fixes-into-compat_do_execve-paths.patch

   1 From 114279be2120a916e8a04feeb2ac976a10016f2f Mon Sep 17 00:00:00 2001
   2 From: Oleg Nesterov <oleg@redhat.com>
   3 Date: Tue, 30 Nov 2010 20:56:02 +0100
   4 Subject: exec: copy-and-paste the fixes into compat_do_execve() paths
   5
   6 From: Oleg Nesterov <oleg@redhat.com>
   7
   8 commit 114279be2120a916e8a04feeb2ac976a10016f2f upstream.
   9
  10 Note: this patch targets 2.6.37 and tries to be as simple as possible.
  11 That is why it adds more copy-and-paste horror into fs/compat.c and
  12 uglifies fs/exec.c, this will be cleanuped later.
  13
  14 compat_copy_strings() plays with bprm->vma/mm directly and thus has
  15 two problems: it lacks the RLIMIT_STACK check and argv/envp memory
  16 is not visible to oom killer.
  17
  18 Export acct_arg_size() and get_arg_page(), change compat_copy_strings()
  19 to use get_arg_page(), change compat_do_execve() to do acct_arg_size(0)
  20 as do_execve() does.
  21
  22 Add the fatal_signal_pending/cond_resched checks into compat_count() and
  23 compat_copy_strings(), this matches the code in fs/exec.c and certainly
  24 makes sense.
  25
  26 Signed-off-by: Oleg Nesterov <oleg@redhat.com>
  27 Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
  28 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  29 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  30
  31 ---
  32  fs/compat.c             |   28 +++++++++++++++-------------
  33  fs/exec.c               |    8 ++++----
  34  include/linux/binfmts.h |    4 ++++
  35  3 files changed, 23 insertions(+), 17 deletions(-)
  36
  37 --- a/fs/compat.c
  38 +++ b/fs/compat.c
  39 @@ -1378,6 +1378,10 @@ static int compat_count(compat_uptr_t __
  40                         argv++;
  41                         if (i++ >= max)
  42                                 return -E2BIG;
  43 +
  44 +                       if (fatal_signal_pending(current))
  45 +                               return -ERESTARTNOHAND;
  46 +                       cond_resched();
  47                 }
  48         }
  49         return i;
  50 @@ -1419,6 +1423,12 @@ static int compat_copy_strings(int argc,
  51                 while (len > 0) {
  52                         int offset, bytes_to_copy;
  53
  54 +                       if (fatal_signal_pending(current)) {
  55 +                               ret = -ERESTARTNOHAND;
  56 +                               goto out;
  57 +                       }
  58 +                       cond_resched();
  59 +
  60                         offset = pos % PAGE_SIZE;
  61                         if (offset == 0)
  62                                 offset = PAGE_SIZE;
  63 @@ -1435,18 +1445,8 @@ static int compat_copy_strings(int argc,
  64                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
  65                                 struct page *page;
  66
  67 -#ifdef CONFIG_STACK_GROWSUP
  68 -                               ret = expand_stack_downwards(bprm->vma, pos);
  69 -                               if (ret < 0) {
  70 -                                       /* We've exceed the stack rlimit. */
  71 -                                       ret = -E2BIG;
  72 -                                       goto out;
  73 -                               }
  74 -#endif
  75 -                               ret = get_user_pages(current, bprm->mm, pos,
  76 -                                                    1, 1, 1, &page, NULL);
  77 -                               if (ret <= 0) {
  78 -                                       /* We've exceed the stack rlimit. */
  79 +                               page = get_arg_page(bprm, pos, 1);
  80 +                               if (!page) {
  81                                         ret = -E2BIG;
  82                                         goto out;
  83                                 }
  84 @@ -1567,8 +1567,10 @@ int compat_do_execve(char * filename,
  85         return retval;
  86
  87  out:
  88 -       if (bprm->mm)
  89 +       if (bprm->mm) {
  90 +               acct_arg_size(bprm, 0);
  91                 mmput(bprm->mm);
  92 +       }
  93
  94  out_file:
  95         if (bprm->file) {
  96 --- a/fs/exec.c
  97 +++ b/fs/exec.c
  98 @@ -157,7 +157,7 @@ out:
  99
 100  #ifdef CONFIG_MMU
 101
 102 -static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 103 +void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 104  {
 105         struct mm_struct *mm = current->mm;
 106         long diff = (long)(pages - bprm->vma_pages);
 107 @@ -176,7 +176,7 @@ static void acct_arg_size(struct linux_b
 108  #endif
 109  }
 110
 111 -static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 112 +struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 113                 int write)
 114  {
 115         struct page *page;
 116 @@ -290,11 +290,11 @@ static bool valid_arg_len(struct linux_b
 117
 118  #else
 119
 120 -static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 121 +void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 122  {
 123  }
 124
 125 -static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 126 +struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 127                 int write)
 128  {
 129         struct page *page;
 130 --- a/include/linux/binfmts.h
 131 +++ b/include/linux/binfmts.h
 132 @@ -60,6 +60,10 @@ struct linux_binprm{
 133         unsigned long loader, exec;
 134  };
 135
 136 +extern void acct_arg_size(struct linux_binprm *bprm, unsigned long pages);
 137 +extern struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 138 +                                       int write);
 139 +
 140  #define BINPRM_FLAGS_ENFORCE_NONDUMP_BIT 0
 141  #define BINPRM_FLAGS_ENFORCE_NONDUMP (1 << BINPRM_FLAGS_ENFORCE_NONDUMP_BIT)
 142