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56 lines
2.5 KiB
56 lines
2.5 KiB
commit 0fc2d46fabb2b9317daf7030162e828c7e1684d5
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Author: Christopher Faulet <cfaulet@haproxy.com>
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Date: Thu Aug 1 10:09:29 2019 +0200
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BUG/MEDIUM: lb-chash: Ensure the tree integrity when server weight is increased
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When the server weight is increased in consistant hash, extra nodes have to be
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allocated. So a realloc() is performed on the nodes array of the server. the
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previous commit 962ea7732 ("BUG/MEDIUM: lb-chash: Remove all server's entries
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before realloc() to re-insert them after") have fixed the size used during the
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realloc() to avoid segfaults. But another bug remains. After the realloc(), the
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memory area allocated for the nodes array may change, invalidating all node
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addresses in the chash tree.
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So, to fix the bug, we must remove all server's entries from the chash tree
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before the realloc to insert all of them after, old nodes and new ones. The
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insert will be automatically handled by the loop at the end of the function
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chash_queue_dequeue_srv().
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Note that if the call to realloc() failed, no new entries will be created for
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the server, so the effective server weight will be unchanged.
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This issue was reported on Github (#189).
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This patch must be backported to all versions since the 1.6.
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(cherry picked from commit 0a52c17f819a5b0a17718b605bdd990b9e2b58e6)
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Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
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diff --git a/src/lb_chash.c b/src/lb_chash.c
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index 0bf4e81a..23448df8 100644
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--- a/src/lb_chash.c
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+++ b/src/lb_chash.c
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@@ -84,8 +84,13 @@ static inline void chash_queue_dequeue_srv(struct server *s)
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* increased the weight beyond the original weight
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*/
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if (s->lb_nodes_tot < s->next_eweight) {
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- struct tree_occ *new_nodes = realloc(s->lb_nodes, s->next_eweight * sizeof(*new_nodes));
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+ struct tree_occ *new_nodes;
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+ /* First we need to remove all server's entries from its tree
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+ * because the realloc will change all nodes pointers */
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+ chash_dequeue_srv(s);
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+
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+ new_nodes = realloc(s->lb_nodes, s->next_eweight * sizeof(*new_nodes));
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if (new_nodes) {
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unsigned int j;
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@@ -494,7 +499,6 @@ void chash_init_server_tree(struct proxy *p)
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srv->lb_nodes_tot = srv->uweight * BE_WEIGHT_SCALE;
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srv->lb_nodes_now = 0;
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srv->lb_nodes = calloc(srv->lb_nodes_tot, sizeof(struct tree_occ));
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-
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for (node = 0; node < srv->lb_nodes_tot; node++) {
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srv->lb_nodes[node].server = srv;
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srv->lb_nodes[node].node.key = full_hash(srv->puid * SRV_EWGHT_RANGE + node);
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