releases/3.18.95/kernfs-fix-regression-in-kernfs_fop_write-caused-by-wrong-type.patch

   1 From ba87977a49913129962af8ac35b0e13e0fa4382d Mon Sep 17 00:00:00 2001
   2 From: Ivan Vecera <ivecera@redhat.com>
   3 Date: Fri, 19 Jan 2018 09:18:54 +0100
   4 Subject: kernfs: fix regression in kernfs_fop_write caused by wrong type
   5
   6 From: Ivan Vecera <ivecera@redhat.com>
   7
   8 commit ba87977a49913129962af8ac35b0e13e0fa4382d upstream.
   9
  10 Commit b7ce40cff0b9 ("kernfs: cache atomic_write_len in
  11 kernfs_open_file") changes type of local variable 'len' from ssize_t
  12 to size_t. This change caused that the *ppos value is updated also
  13 when the previous write callback failed.
  14
  15 Mentioned snippet:
  16 ...
  17 len = ops->write(...); <- return value can be negative
  18 ...
  19 if (len > 0)           <- true here in this case
  20         *ppos += len;
  21 ...
  22
  23 Fixes: b7ce40cff0b9 ("kernfs: cache atomic_write_len in kernfs_open_file")
  24 Acked-by: Tejun Heo <tj@kernel.org>
  25 Signed-off-by: Ivan Vecera <ivecera@redhat.com>
  26 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
  27 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  28
  29 ---
  30  fs/kernfs/file.c |    2 +-
  31  1 file changed, 1 insertion(+), 1 deletion(-)
  32
  33 --- a/fs/kernfs/file.c
  34 +++ b/fs/kernfs/file.c
  35 @@ -267,7 +267,7 @@ static ssize_t kernfs_fop_write(struct f
  36  {
  37         struct kernfs_open_file *of = kernfs_of(file);
  38         const struct kernfs_ops *ops;
  39 -       size_t len;
  40 +       ssize_t len;
  41         char *buf;
  42
  43         if (of->atomic_write_len) {