[Tarantool-patches] [PATCH v3 1/1] iproto: don't destroy a session during disconnect

[Vladislav Shpilevoy]

I forgot to push a test file. Here it is.

================================================================================

diff --git a/test/box/gh-4627-session-use-after-free.result b/test/box/gh-4627-session-use-after-free.result
new file mode 100644
index 000000000..5e5c154b9
--- /dev/null
+++ b/test/box/gh-4627-session-use-after-free.result
@@ -0,0 +1,60 @@
+-- test-run result file version 2
+--
+-- gh-4627: binary session disconnect trigger yield could lead to
+-- use after free of the session object. That happened because
+-- iproto thread sent two requests to TX thread at disconnect:
+--
+--     - Close the session and run its on disconnect triggers;
+--
+--     - If all requests are handled, destroy the session.
+--
+-- When a connection is idle, all requests are handled, so both
+-- these requests are sent. If the first one yielded in TX thread,
+-- the second one arrived and destroyed the session right under
+-- the feet of the first one.
+--
+net_box = require('net.box')
+ | ---
+ | ...
+fiber = require('fiber')
+ | ---
+ | ...
+
+sid_before_yield = nil
+ | ---
+ | ...
+sid_after_yield = nil
+ | ---
+ | ...
+func = box.session.on_disconnect(function()     \
+    sid_before_yield = box.session.id()         \
+    fiber.yield()                               \
+    sid_after_yield = box.session.id()          \
+end)
+ | ---
+ | ...
+
+connection = net_box.connect(box.cfg.listen)
+ | ---
+ | ...
+connection:ping()
+ | ---
+ | - true
+ | ...
+connection:close()
+ | ---
+ | ...
+
+while not sid_after_yield do fiber.yield() end
+ | ---
+ | ...
+
+sid_after_yield == sid_before_yield and sid_after_yield ~= 0 or \
+    {sid_after_yield, sid_before_yield}
+ | ---
+ | - true
+ | ...
+
+box.session.on_disconnect(nil, func)
+ | ---
+ | ...
diff --git a/test/box/gh-4627-session-use-after-free.test.lua b/test/box/gh-4627-session-use-after-free.test.lua
new file mode 100644
index 000000000..70624a96a
--- /dev/null
+++ b/test/box/gh-4627-session-use-after-free.test.lua
@@ -0,0 +1,35 @@
+--
+-- gh-4627: binary session disconnect trigger yield could lead to
+-- use after free of the session object. That happened because
+-- iproto thread sent two requests to TX thread at disconnect:
+--
+--     - Close the session and run its on disconnect triggers;
+--
+--     - If all requests are handled, destroy the session.
+--
+-- When a connection is idle, all requests are handled, so both
+-- these requests are sent. If the first one yielded in TX thread,
+-- the second one arrived and destroyed the session right under
+-- the feet of the first one.
+--
+net_box = require('net.box')
+fiber = require('fiber')
+
+sid_before_yield = nil
+sid_after_yield = nil
+func = box.session.on_disconnect(function()     \
+    sid_before_yield = box.session.id()         \
+    fiber.yield()                               \
+    sid_after_yield = box.session.id()          \
+end)
+
+connection = net_box.connect(box.cfg.listen)
+connection:ping()
+connection:close()
+
+while not sid_after_yield do fiber.yield() end
+
+sid_after_yield == sid_before_yield and sid_after_yield ~= 0 or \
+    {sid_after_yield, sid_before_yield}
+
+box.session.on_disconnect(nil, func)