From: JP Abgrall <jpa@google.com>
Date: Sat, 8 Oct 2011 05:14:24 +0000 (-0700)
Subject: netfilter: xt_qtaguid: fix crash on ctrl delete command
X-Git-Tag: firefly_0821_release~7613^2~268
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=8493beb1045539c0c43c07c6adeb71e3c00d990a;p=firefly-linux-kernel-4.4.55.git

netfilter: xt_qtaguid: fix crash on ctrl delete command

Because for now the xt_qtaguid module allows procs to use tags without
having /dev/xt_qtaguid open, there was a case where it would try
to delete a resources from a list that was proc specific.
But that resource was never added to that list which is only
used when /dev/xt_qtaguid has been opened by the proc.

Once our userspace is fully updated, we won't need those exceptions.

Change-Id: Idd4bfea926627190c74645142916e10832eb2504
Signed-off-by: JP Abgrall <jpa@google.com>
---

diff --git a/net/netfilter/xt_qtaguid.c b/net/netfilter/xt_qtaguid.c
index 5d73ecaf540a..08086d680c2c 100644
--- a/net/netfilter/xt_qtaguid.c
+++ b/net/netfilter/xt_qtaguid.c
@@ -1919,7 +1919,15 @@ static int ctrl_cmd_delete(const char *input)
 			tr_entry = lookup_tag_ref(st_entry->tag, NULL);
 			BUG_ON(tr_entry->num_sock_tags <= 0);
 			tr_entry->num_sock_tags--;
-			list_del(&st_entry->list);
+			/*
+			 * TODO: remove if, and start failing.
+			 * This is a hack to work around the fact that in some
+			 * places we have "if (IS_ERR_OR_NULL(pqd_entry))"
+			 * and are trying to work around apps
+			 * that didn't open the /dev/xt_qtaguid.
+			 */
+			if (st_entry->list.next && st_entry->list.prev)
+				list_del(&st_entry->list);
 		}
 	}
 	spin_unlock_bh(&sock_tag_list_lock);