wifi: iwlwifi: fix out of bound copy_from_user

The driver copies the userspace buffer into an internal NUL
byte terminated buffer. While doing so, it was reading beyond
the end of the userspace buffer, overwriting its own NUL
termination in the process.

Fix this by only copying the correct number of bytes.

Fixes: 3f244876ef73 ("wifi: iwlwifi: make debugfs entries link specific")
Signed-off-by: Anjaneyulu <pagadala.yesu.anjaneyulu@intel.com>
Reviewed-by: Gregory Greenman <gregory.greenman@intel.com>
Reviewed-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20231219215605.e4913deb2ad4.Idcf6a7e909ff4b7801cd49c2f691f84a2f68eff9@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs.c b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs.c
index e016fce7ab246418e82cb246bac1c98a8b86109b..16a104de8371751eb6c7fb74c94c2e7029979eb0 100644 (file)
--- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs.c
@@ -1829,7 +1829,7 @@ static ssize_t _iwl_dbgfs_link_sta_##name##_write(struct file *file,      \
        char buf[buflen] = {};                                          \
        size_t buf_size = min(count, sizeof(buf) -  1);                 \
                                                                        \
-       if (copy_from_user(buf, user_buf, sizeof(buf)))                 \
+       if (copy_from_user(buf, user_buf, buf_size))                    \
                return -EFAULT;                                         \
                                                                        \
        return _iwl_dbgfs_link_sta_wrap_write(iwl_dbgfs_##name##_write, \