commit 5b259db1160fa12820cc5ba6399e4dbcefa6ab22
Author: Olivier Houchard <ohouchard@haproxy.com>
Date:   Wed Nov 14 17:54:36 2018 +0100

    BUG/MEDIUM: Make sure stksess is properly aligned.
    
    When we allocate struct stksess, we also allocate memory to store the
    associated data before the struct itself.
    As the data can be of different types, they can have different size. However,
    we need the struct stksess to be properly aligned, as it can do 64bits
    load/store (including atomic load/stores) on 64bits platforms, and some of
    them doesn't support unaligned access.
    So, when allocating the struct stksess, round the size up to the next
    multiple of sizeof(void *), and make sure the struct stksess itself is
    properly aligned.
    Many thanks to Paul Martin for investigating and reporting that bug.
    
    This should be backported to earlier releases.
    
    (cherry picked from commit 52dabbc4fad338233c7f0c96f977a43f8f81452a)
    Signed-off-by: William Lallemand <wlallemand@haproxy.org>

diff --git a/src/stick_table.c b/src/stick_table.c
index f1442603..0a238378 100644
--- a/src/stick_table.c
+++ b/src/stick_table.c
@@ -44,6 +44,7 @@
 /* structure used to return a table key built from a sample */
 static THREAD_LOCAL struct stktable_key static_table_key;
 
+#define round_ptr_size(i) (((i) + (sizeof(void *) - 1)) &~ (sizeof(void *) - 1))
 /*
  * Free an allocated sticky session <ts>, and decrease sticky sessions counter
  * in table <t>.
@@ -51,7 +52,7 @@ static THREAD_LOCAL struct stktable_key static_table_key;
 void __stksess_free(struct stktable *t, struct stksess *ts)
 {
 	t->current--;
-	pool_free(t->pool, (void *)ts - t->data_size);
+	pool_free(t->pool, (void *)ts - round_ptr_size(t->data_size));
 }
 
 /*
@@ -229,7 +230,7 @@ struct stksess *__stksess_new(struct stktable *t, struct stktable_key *key)
 	ts = pool_alloc(t->pool);
 	if (ts) {
 		t->current++;
-		ts = (void *)ts + t->data_size;
+		ts = (void *)ts + round_ptr_size(t->data_size);
 		__stksess_init(t, ts);
 		if (key)
 			stksess_setkey(t, ts, key);
@@ -597,7 +598,7 @@ int stktable_init(struct stktable *t)
 		t->updates = EB_ROOT_UNIQUE;
 		HA_SPIN_INIT(&t->lock);
 
-		t->pool = create_pool("sticktables", sizeof(struct stksess) + t->data_size + t->key_size, MEM_F_SHARED);
+		t->pool = create_pool("sticktables", sizeof(struct stksess) + round_ptr_size(t->data_size) + t->key_size, MEM_F_SHARED);
 
 		t->exp_next = TICK_ETERNITY;
 		if ( t->expire ) {