netfitler: xt_qtaguid: add another missing spin_unlock.

This time the symptom is caused by tagging the same socket twice
without untagging it in between.
This would cause it to not unlock, and return.

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

diff --git a/net/netfilter/xt_qtaguid.c b/net/netfilter/xt_qtaguid.c
index 3cacec0..49ed432 100644 (file)
--- a/net/netfilter/xt_qtaguid.c
+++ b/net/netfilter/xt_qtaguid.c
@@ -997,11 +997,13 @@ static int qtaguid_ctrl_parse(const char *input, int count)
                sock_tag_entry = get_sock_stat_nl(el_socket->sk);
                if (!sock_tag_entry)
                        spin_unlock_irqrestore(&sock_tag_list_lock, flags);
+               /* HERE: The lock is held if there was a matching sock tag entry */
                break;
        default:
                res = -EINVAL;
                goto err;
        }
+       /* HERE: The lock is held if there was a matching sock tag entry */
 
        /* Process commands */
        switch (cmd) {
@@ -1009,17 +1011,23 @@ static int qtaguid_ctrl_parse(const char *input, int count)
        case 't':
                if (argc < 2) {
                        res = -EINVAL;
+                       /* HERE: The lock is held if there was a matching sock
+                        * tag entry */
                        goto err_unlock;
                }
                if (argc < 3) {
                        acct_tag = 0;
                } else if (!valid_atag(acct_tag)) {
                        res = -EINVAL;
+                       /* HERE: The lock is held if there was a matching sock
+                        * tag entry */
                        goto err_unlock;
                }
                if (argc < 4)
                        uid = current_fsuid();
                if (!sock_tag_entry) {
+                       /* HERE: There is no lock held because there was no
+                        * sock tag entry */
                        sock_tag_entry = kmalloc(sizeof(*sock_tag_entry),
                                                GFP_KERNEL);
                        if (!sock_tag_entry) {
@@ -1034,13 +1042,15 @@ static int qtaguid_ctrl_parse(const char *input, int count)
                                                                uid);
                        spin_lock_irqsave(&sock_tag_list_lock, flags);
                        sock_tag_tree_insert(sock_tag_entry, &sock_tag_tree);
-                       spin_unlock_irqrestore(&sock_tag_list_lock, flags);
                } else {
+                       /* HERE: The lock is held because there is a matching
+                        * sock tag entry */
                        /* Just update the acct_tag portion. */
                        uid_t orig_uid = get_uid_from_tag(sock_tag_entry->tag);
                        sock_tag_entry->tag = combine_atag_with_uid(acct_tag,
                                                                orig_uid);
                }
+               spin_unlock_irqrestore(&sock_tag_list_lock, flags);
                pr_debug("xt_qtaguid: tag: sock_tag_entry->sk=%p "
                        "...->tag=0x%llx (uid=%u)\n",
                        sock_tag_entry->sk, sock_tag_entry->tag,