releases/4.9.28/iwlwifi-mvm-writing-zero-bytes-to-debugfs-causes-a-crash.patch

   1 From 251fe09f13bfb54c1ede66ee8bf8ddd0061c4f7c Mon Sep 17 00:00:00 2001
   2 From: Dan Carpenter <dan.carpenter@oracle.com>
   3 Date: Thu, 23 Mar 2017 13:40:00 +0300
   4 Subject: iwlwifi: mvm: writing zero bytes to debugfs causes a crash
   5
   6 From: Dan Carpenter <dan.carpenter@oracle.com>
   7
   8 commit 251fe09f13bfb54c1ede66ee8bf8ddd0061c4f7c upstream.
   9
  10 This is a static analysis fix.  The warning is:
  11
  12         drivers/net/wireless/intel/iwlwifi/mvm/fw-dbg.c:912 iwl_mvm_fw_dbg_collect()
  13         warn: integer overflows 'sizeof(*desc) + len'
  14
  15 I guess this code is supposed to take a NUL character, but if we write
  16 zero bytes then it tries to write -1 characters and crashes.
  17
  18 Fixes: c91b865cb14d ("iwlwifi: mvm: support description for user triggered fw dbg collection")
  19 Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
  20 Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
  21 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  22
  23 ---
  24  drivers/net/wireless/intel/iwlwifi/mvm/debugfs.c |    2 ++
  25  1 file changed, 2 insertions(+)
  26
  27 --- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs.c
  28 +++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs.c
  29 @@ -1056,6 +1056,8 @@ static ssize_t iwl_dbgfs_fw_dbg_collect_
  30
  31         if (ret)
  32                 return ret;
  33 +       if (count == 0)
  34 +               return 0;
  35
  36         iwl_mvm_fw_dbg_collect(mvm, FW_DBG_TRIGGER_USER, buf,
  37                                (count - 1), NULL);