releases/3.0.16/oprofile-fix-uninitialized-memory-access-when-writing-to-writing-to-oprofilefs.patch

   1 From 913050b91eb94f194392dd797b1ff3779f606ac0 Mon Sep 17 00:00:00 2001
   2 From: Robert Richter <robert.richter@amd.com>
   3 Date: Mon, 19 Dec 2011 16:38:30 +0100
   4 Subject: oprofile: Fix uninitialized memory access when writing to writing to oprofilefs
   5
   6 From: Robert Richter <robert.richter@amd.com>
   7
   8 commit 913050b91eb94f194392dd797b1ff3779f606ac0 upstream.
   9
  10 If oprofilefs_ulong_from_user() is called with count equals
  11 zero, *val remains unchanged. Depending on the implementation it
  12 might be uninitialized.
  13
  14 Change oprofilefs_ulong_from_user()'s interface to return count
  15 on success. Thus, we are able to return early if count equals
  16 zero which avoids using *val uninitialized. Fixing all users of
  17 oprofilefs_ulong_ from_user().
  18
  19 This follows write syscall implementation when count is zero:
  20 "If count is zero ... [and if] no errors are detected, 0 will be
  21 returned without causing any other effect." (man 2 write)
  22
  23 Reported-By: Mike Waychison <mikew@google.com>
  24 Signed-off-by: Robert Richter <robert.richter@amd.com>
  25 Cc: Andrew Morton <akpm@linux-foundation.org>
  26 Cc: oprofile-list <oprofile-list@lists.sourceforge.net>
  27 Link: http://lkml.kernel.org/r/20111219153830.GH16765@erda.amd.com
  28 Signed-off-by: Ingo Molnar <mingo@elte.hu>
  29 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  30
  31 ---
  32  arch/s390/oprofile/init.c         |    2 +-
  33  drivers/oprofile/oprofile_files.c |    7 ++++---
  34  drivers/oprofile/oprofilefs.c     |   11 +++++++++--
  35  3 files changed, 14 insertions(+), 6 deletions(-)
  36
  37 --- a/arch/s390/oprofile/init.c
  38 +++ b/arch/s390/oprofile/init.c
  39 @@ -90,7 +90,7 @@ static ssize_t hwsampler_write(struct fi
  40                 return -EINVAL;
  41
  42         retval = oprofilefs_ulong_from_user(&val, buf, count);
  43 -       if (retval)
  44 +       if (retval <= 0)
  45                 return retval;
  46
  47         if (oprofile_started)
  48 --- a/drivers/oprofile/oprofile_files.c
  49 +++ b/drivers/oprofile/oprofile_files.c
  50 @@ -45,7 +45,7 @@ static ssize_t timeout_write(struct file
  51                 return -EINVAL;
  52
  53         retval = oprofilefs_ulong_from_user(&val, buf, count);
  54 -       if (retval)
  55 +       if (retval <= 0)
  56                 return retval;
  57
  58         retval = oprofile_set_timeout(val);
  59 @@ -84,7 +84,7 @@ static ssize_t depth_write(struct file *
  60                 return -EINVAL;
  61
  62         retval = oprofilefs_ulong_from_user(&val, buf, count);
  63 -       if (retval)
  64 +       if (retval <= 0)
  65                 return retval;
  66
  67         retval = oprofile_set_ulong(&oprofile_backtrace_depth, val);
  68 @@ -141,9 +141,10 @@ static ssize_t enable_write(struct file
  69                 return -EINVAL;
  70
  71         retval = oprofilefs_ulong_from_user(&val, buf, count);
  72 -       if (retval)
  73 +       if (retval <= 0)
  74                 return retval;
  75
  76 +       retval = 0;
  77         if (val)
  78                 retval = oprofile_start();
  79         else
  80 --- a/drivers/oprofile/oprofilefs.c
  81 +++ b/drivers/oprofile/oprofilefs.c
  82 @@ -60,6 +60,13 @@ ssize_t oprofilefs_ulong_to_user(unsigne
  83  }
  84
  85
  86 +/*
  87 + * Note: If oprofilefs_ulong_from_user() returns 0, then *val remains
  88 + * unchanged and might be uninitialized. This follows write syscall
  89 + * implementation when count is zero: "If count is zero ... [and if]
  90 + * no errors are detected, 0 will be returned without causing any
  91 + * other effect." (man 2 write)
  92 + */
  93  int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count)
  94  {
  95         char tmpbuf[TMPBUFSIZE];
  96 @@ -79,7 +86,7 @@ int oprofilefs_ulong_from_user(unsigned
  97         spin_lock_irqsave(&oprofilefs_lock, flags);
  98         *val = simple_strtoul(tmpbuf, NULL, 0);
  99         spin_unlock_irqrestore(&oprofilefs_lock, flags);
 100 -       return 0;
 101 +       return count;
 102  }
 103
 104
 105 @@ -99,7 +106,7 @@ static ssize_t ulong_write_file(struct f
 106                 return -EINVAL;
 107
 108         retval = oprofilefs_ulong_from_user(&value, buf, count);
 109 -       if (retval)
 110 +       if (retval <= 0)
 111                 return retval;
 112
 113         retval = oprofile_set_ulong(file->private_data, value);