ANDROID: xt_qtaguid: fix UAF race

ANDROID: xt_qtaguid: fix UAF race

Make sure to hold the sock_tag_list_lock while accessing the tag to
avoid a race between getting the tag and free'ing the tag.

Mot-CRs-fixed: (CR)
CVE-Fixed: CVE-2021-0695

Bug: 184018316
Fixes: c7ca0ac69702 ("ANDROID: netfilter: xt_qtaguid: add qtaguid matching module")
Signed-off-by: Will McVicker <willmcvicker@google.com>
Change-Id: I62404bdaa602586e00821a7d4c5f9b9868a0e90a
Signed-off-by: Gajjala Chakradhar <gajjalac@motorola.com>
Reviewed-on: https://gerrit.mot.com/2045010
SLTApproved: Slta Waiver
SME-Granted: SME Approvals Granted
Tested-by: Jira Key
Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>
Submit-Approved: Jira Key
(cherry picked from commit e04c6a8a906faadbcd7af351538461ded66c6bae)