queue-4.4/bcache-fix-input-overflow-to-cache-set-sysfs-file-io.patch

   1 From e58d7975d11bda8a4a5139ade371c131b7041434 Mon Sep 17 00:00:00 2001
   2 From: Coly Li <colyli@suse.de>
   3 Date: Sat, 9 Feb 2019 12:53:10 +0800
   4 Subject: bcache: fix input overflow to cache set sysfs file io_error_halflife
   5
   6 [ Upstream commit a91fbda49f746119828f7e8ad0f0aa2ab0578f65 ]
   7
   8 Cache set sysfs entry io_error_halflife is used to set c->error_decay.
   9 c->error_decay is in type unsigned int, and it is converted by
  10 strtoul_or_return(), therefore overflow to c->error_decay is possible
  11 for a large input value.
  12
  13 This patch fixes the overflow by using strtoul_safe_clamp() to convert
  14 input string to an unsigned long value in range [0, UINT_MAX], then
  15 divides by 88 and set it to c->error_decay.
  16
  17 Signed-off-by: Coly Li <colyli@suse.de>
  18 Signed-off-by: Jens Axboe <axboe@kernel.dk>
  19 Signed-off-by: Sasha Levin <sashal@kernel.org>
  20 ---
  21  drivers/md/bcache/sysfs.c | 13 +++++++++++--
  22  1 file changed, 11 insertions(+), 2 deletions(-)
  23
  24 diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
  25 index 5a5c1f1bd8a5..87daccbbc61b 100644
  26 --- a/drivers/md/bcache/sysfs.c
  27 +++ b/drivers/md/bcache/sysfs.c
  28 @@ -645,8 +645,17 @@ STORE(__bch_cache_set)
  29                 c->error_limit = strtoul_or_return(buf) << IO_ERROR_SHIFT;
  30
  31         /* See count_io_errors() for why 88 */
  32 -       if (attr == &sysfs_io_error_halflife)
  33 -               c->error_decay = strtoul_or_return(buf) / 88;
  34 +       if (attr == &sysfs_io_error_halflife) {
  35 +               unsigned long v = 0;
  36 +               ssize_t ret;
  37 +
  38 +               ret = strtoul_safe_clamp(buf, v, 0, UINT_MAX);
  39 +               if (!ret) {
  40 +                       c->error_decay = v / 88;
  41 +                       return size;
  42 +               }
  43 +               return ret;
  44 +       }
  45
  46         sysfs_strtoul(journal_delay_ms,         c->journal_delay_ms);
  47         sysfs_strtoul(verify,                   c->verify);
  48 --
  49 2.19.1
  50