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SUSE:SLE-15-SP5:GA
bind.34201
bind-CVE-2023-6516.patch
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File bind-CVE-2023-6516.patch of Package bind.34201
Index: bind-9.16.6/lib/dns/include/dns/rbt.h =================================================================== --- bind-9.16.6.orig/lib/dns/include/dns/rbt.h +++ bind-9.16.6/lib/dns/include/dns/rbt.h @@ -137,6 +137,12 @@ struct dns_rbtnode { */ ISC_LINK(dns_rbtnode_t) deadlink; + /*% + * This linked list is used to store nodes from which tree pruning can + * be started. + */ + ISC_LINK(dns_rbtnode_t) prunelink; + /*@{*/ /*! * These values are used in the RBT DB implementation. The appropriate Index: bind-9.16.6/lib/dns/mapapi =================================================================== --- bind-9.16.6.orig/lib/dns/mapapi +++ bind-9.16.6/lib/dns/mapapi @@ -13,4 +13,4 @@ # Whenever releasing a new major release of BIND9, set this value # back to 1.0 when releasing the first alpha. Map files are *never* # compatible across major releases. -MAPAPI=2.0 +MAPAPI=4.0 Index: bind-9.16.6/lib/dns/rbt.c =================================================================== --- bind-9.16.6.orig/lib/dns/rbt.c +++ bind-9.16.6/lib/dns/rbt.c @@ -2258,6 +2258,7 @@ create_node(isc_mem_t *mctx, const dns_n HASHVAL(node) = 0; ISC_LINK_INIT(node, deadlink); + ISC_LINK_INIT(node, prunelink); LOCKNUM(node) = 0; WILD(node) = 0; Index: bind-9.16.6/lib/dns/rbtdb.c =================================================================== --- bind-9.16.6.orig/lib/dns/rbtdb.c +++ bind-9.16.6/lib/dns/rbtdb.c @@ -490,6 +490,10 @@ struct dns_rbtdb { */ rbtnodelist_t *deadnodes; + /* List of nodes from which recursive tree pruning can be started from. + * Locked by tree_lock. */ + rbtnodelist_t prunenodes; + /* * Heaps. These are used for TTL based expiry in a cache, * or for zone resigning in a zone DB. hmctx is the memory @@ -1035,6 +1039,7 @@ free_rbtdb(dns_rbtdb_t *rbtdb, bool log, unsigned int i; isc_result_t result; char buf[DNS_NAME_FORMATSIZE]; + dns_rbtnode_t *node = NULL; dns_rbt_t **treep; isc_time_t start; dns_dbonupdatelistener_t *listener, *listener_next; @@ -1061,8 +1066,6 @@ free_rbtdb(dns_rbtdb_t *rbtdb, bool log, * the overhead of unlinking all nodes here should be negligible. */ for (i = 0; i < rbtdb->node_lock_count; i++) { - dns_rbtnode_t *node; - node = ISC_LIST_HEAD(rbtdb->deadnodes[i]); while (node != NULL) { ISC_LIST_UNLINK(rbtdb->deadnodes[i], node, deadlink); @@ -1070,6 +1073,12 @@ free_rbtdb(dns_rbtdb_t *rbtdb, bool log, } } + node = ISC_LIST_HEAD(rbtdb->prunenodes); + while (node != NULL) { + ISC_LIST_UNLINK(rbtdb->prunenodes, node, prunelink); + node = ISC_LIST_HEAD(rbtdb->prunenodes); + } + if (event == NULL) { rbtdb->quantum = (rbtdb->task != NULL) ? 100 : 0; } @@ -1938,19 +1947,32 @@ is_leaf(dns_rbtnode_t *node) { node->left == NULL && node->right == NULL); } +/*% + * The tree lock must be held when this function is called as it reads and + * updates rbtdb->prunenodes. + */ static inline void send_to_prune_tree(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node, isc_rwlocktype_t locktype) { - isc_event_t *ev; - dns_db_t *db; + bool pruning_queued = (ISC_LIST_HEAD(rbtdb->prunenodes) != NULL); + + INSIST(locktype == isc_rwlocktype_write); - ev = isc_event_allocate(rbtdb->common.mctx, NULL, DNS_EVENT_RBTPRUNE, - prune_tree, node, sizeof(isc_event_t)); new_reference(rbtdb, node, locktype); - db = NULL; - attach((dns_db_t *)rbtdb, &db); - ev->ev_sender = db; - isc_task_send(rbtdb->task, &ev); + INSIST(!ISC_LINK_LINKED(node, prunelink)); + ISC_LIST_APPEND(rbtdb->prunenodes, node, prunelink); + + if (!pruning_queued) { + isc_event_t *ev = NULL; + dns_db_t *db = NULL; + + attach((dns_db_t *)rbtdb, &db); + + ev = isc_event_allocate(rbtdb->common.mctx, NULL, + DNS_EVENT_RBTPRUNE, prune_tree, db, + sizeof(isc_event_t)); + isc_task_send(rbtdb->task, &ev); + } } /*% @@ -2224,17 +2246,26 @@ restore_locks: } /* - * Prune the tree by recursively cleaning-up single leaves. In the worst - * case, the number of iteration is the number of tree levels, which is at - * most the maximum number of domain name labels, i.e, 127. In practice, this - * should be much smaller (only a few times), and even the worst case would be - * acceptable for a single event. + * Prune the tree by recursively cleaning up single leaves. Go through all + * nodes stored in the rbtdb->prunenodes list; for each of them, in the worst + * case, it will be necessary to traverse a number of tree levels equal to the + * maximum legal number of domain name labels (127); in practice, the number of + * tree levels to traverse will virtually always be much smaller (a few levels + * at most). While holding the tree lock throughout this entire operation is + * less than ideal, so is splitting the latter up by queueing a separate + * prune_tree() run for each node to start pruning from (as queueing requires + * allocating memory and can therefore potentially be exploited to exhaust + * available memory). Also note that actually freeing up the memory used by + * RBTDB nodes (which is what this function does) is essential to keeping cache + * memory use in check, so since the tree lock needs to be acquired anyway, + * freeing as many nodes as possible before the tree lock gets released is + * prudent. */ static void prune_tree(isc_task_t *task, isc_event_t *event) { - dns_rbtdb_t *rbtdb = event->ev_sender; - dns_rbtnode_t *node = event->ev_arg; - dns_rbtnode_t *parent; + dns_rbtdb_t *rbtdb = (dns_rbtdb_t *)event->ev_arg; + dns_rbtnode_t *node = NULL; + dns_rbtnode_t *parent = NULL; unsigned int locknum; UNUSED(task); @@ -2242,44 +2273,60 @@ prune_tree(isc_task_t *task, isc_event_t isc_event_free(&event); RWLOCK(&rbtdb->tree_lock, isc_rwlocktype_write); - locknum = node->locknum; - NODE_LOCK(&rbtdb->node_locks[locknum].lock, isc_rwlocktype_write); - do { - parent = node->parent; - decrement_reference(rbtdb, node, 0, isc_rwlocktype_write, - isc_rwlocktype_write, true); - if (parent != NULL && parent->down == NULL) { - /* - * node was the only down child of the parent and has - * just been removed. We'll then need to examine the - * parent. Keep the lock if possible; otherwise, - * release the old lock and acquire one for the parent. - */ - if (parent->locknum != locknum) { - NODE_UNLOCK(&rbtdb->node_locks[locknum].lock, - isc_rwlocktype_write); - locknum = parent->locknum; - NODE_LOCK(&rbtdb->node_locks[locknum].lock, - isc_rwlocktype_write); + while ((node = ISC_LIST_HEAD(rbtdb->prunenodes)) != NULL) { + locknum = node->locknum; + NODE_LOCK(&rbtdb->node_locks[locknum].lock, + isc_rwlocktype_write); + do { + if (ISC_LINK_LINKED(node, prunelink)) { + ISC_LIST_UNLINK(rbtdb->prunenodes, node, + prunelink); } - /* - * We need to gain a reference to the node before - * decrementing it in the next iteration. - */ - if (ISC_LINK_LINKED(parent, deadlink)) { - ISC_LIST_UNLINK(rbtdb->deadnodes[locknum], + parent = node->parent; + decrement_reference(rbtdb, node, 0, + isc_rwlocktype_write, + isc_rwlocktype_write, true); + + if (parent != NULL && parent->down == NULL) { + /* + * node was the only down child of the parent + * and has just been removed. We'll then need + * to examine the parent. Keep the lock if + * possible; otherwise, release the old lock and + * acquire one for the parent. + */ + if (parent->locknum != locknum) { + NODE_UNLOCK( + &rbtdb->node_locks[locknum].lock, + isc_rwlocktype_write); + locknum = parent->locknum; + NODE_LOCK( + &rbtdb->node_locks[locknum].lock, + isc_rwlocktype_write); + } + + /* + * We need to gain a reference to the node + * before decrementing it in the next iteration. + */ + if (ISC_LINK_LINKED(parent, deadlink)) { + ISC_LIST_UNLINK( + rbtdb->deadnodes[locknum], parent, deadlink); + } + new_reference(rbtdb, parent, + isc_rwlocktype_write); + } else { + parent = NULL; } - new_reference(rbtdb, parent, isc_rwlocktype_write); - } else { - parent = NULL; - } - node = parent; - } while (node != NULL); - NODE_UNLOCK(&rbtdb->node_locks[locknum].lock, isc_rwlocktype_write); + node = parent; + } while (node != NULL); + NODE_UNLOCK(&rbtdb->node_locks[locknum].lock, + isc_rwlocktype_write); + } RWUNLOCK(&rbtdb->tree_lock, isc_rwlocktype_write); detach((dns_db_t **)&rbtdb); @@ -8600,6 +8647,8 @@ dns_rbtdb_create(isc_mem_t *mctx, const ISC_LIST_INIT(rbtdb->deadnodes[i]); } + ISC_LIST_INIT(rbtdb->prunenodes); + rbtdb->active = rbtdb->node_lock_count; for (i = 0; i < (int)(rbtdb->node_lock_count); i++) {
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