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BUG/MEDIUM: lua: dead lock when Lua tasks are trigerred

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When a task is created from Lua context out of initialisation,
the hlua_ctx_init() function can be called from safe environement,
so we must not initialise it. While the support of threads appear,
the safe environment set a lock to ensure only one Lua execution
at a time. If we initialize safe environment in another safe
environmenet, we have a dead lock.

this patch adds the support of the idicator "already_safe" whoch
indicates if the context is initialized form safe Lua fonction.

thank to Flakebi for the report

This patch must be backported to haproxy-1.9 and haproxy-1.8
This commit is contained in:
Thierry FOURNIER 2019-01-06 19:04:24 +01:00 committed by Willy Tarreau
parent 1725c2e395
commit bf90ce12aa
1 changed files with 26 additions and 13 deletions
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39
src/hlua.c
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@ -884,16 +884,27 @@ __LJMP void hlua_yieldk(lua_State *L, int nresults, int ctx,
* initialisation fails (example: out of memory error), the lua function * initialisation fails (example: out of memory error), the lua function
* throws an error (longjmp). * throws an error (longjmp).
* *
* In some case (at least one), this function can be called from safe
* environement, so we must not initialise it. While the support of
* threads appear, the safe environment set a lock to ensure only one
* Lua execution at a time. If we initialize safe environment in another
* safe environmenet, we have a dead lock.
*
* set "already_safe" true if the context is initialized form safe
* Lua fonction.
*
* This function manipulates two Lua stacks: the main and the thread. Only * This function manipulates two Lua stacks: the main and the thread. Only
* the main stack can fail. The thread is not manipulated. This function * the main stack can fail. The thread is not manipulated. This function
* MUST NOT manipulate the created thread stack state, because it is not * MUST NOT manipulate the created thread stack state, because it is not
* proctected against errors thrown by the thread stack. * proctected against errors thrown by the thread stack.
*/ */
int hlua_ctx_init(struct hlua *lua, struct task *task) int hlua_ctx_init(struct hlua *lua, struct task *task, int already_safe)
{ {
if (!SET_SAFE_LJMP(gL.T)) { if (!already_safe) {
lua->Tref = LUA_REFNIL; if (!SET_SAFE_LJMP(gL.T)) {
return 0; lua->Tref = LUA_REFNIL;
return 0;
}
} }
lua->Mref = LUA_REFNIL; lua->Mref = LUA_REFNIL;
lua->flags = 0; lua->flags = 0;
@ -901,13 +912,15 @@ int hlua_ctx_init(struct hlua *lua, struct task *task)
lua->T = lua_newthread(gL.T); lua->T = lua_newthread(gL.T);
if (!lua->T) { if (!lua->T) {
lua->Tref = LUA_REFNIL; lua->Tref = LUA_REFNIL;
RESET_SAFE_LJMP(gL.T); if (!already_safe)
RESET_SAFE_LJMP(gL.T);
return 0; return 0;
} }
hlua_sethlua(lua); hlua_sethlua(lua);
lua->Tref = luaL_ref(gL.T, LUA_REGISTRYINDEX); lua->Tref = luaL_ref(gL.T, LUA_REGISTRYINDEX);
lua->task = task; lua->task = task;
RESET_SAFE_LJMP(gL.T); if (!already_safe)
RESET_SAFE_LJMP(gL.T);
return 1; return 1;
} }
@ -6331,7 +6344,7 @@ static int hlua_register_task(lua_State *L)
task->context = hlua; task->context = hlua;
task->process = hlua_process_task; task->process = hlua_process_task;
if (!hlua_ctx_init(hlua, task)) if (!hlua_ctx_init(hlua, task, 1))
WILL_LJMP(luaL_error(L, "Lua out of memory error.")); WILL_LJMP(luaL_error(L, "Lua out of memory error."));
/* Restore the function in the stack. */ /* Restore the function in the stack. */
@ -6368,7 +6381,7 @@ static int hlua_sample_conv_wrapper(const struct arg *arg_p, struct sample *smp,
SEND_ERR(stream->be, "Lua converter '%s': can't initialize Lua context.\n", fcn->name); SEND_ERR(stream->be, "Lua converter '%s': can't initialize Lua context.\n", fcn->name);
return 0; return 0;
} }
if (!hlua_ctx_init(stream->hlua, stream->task)) { if (!hlua_ctx_init(stream->hlua, stream->task, 0)) {
SEND_ERR(stream->be, "Lua converter '%s': can't initialize Lua context.\n", fcn->name); SEND_ERR(stream->be, "Lua converter '%s': can't initialize Lua context.\n", fcn->name);
return 0; return 0;
} }
@ -6500,7 +6513,7 @@ static int hlua_sample_fetch_wrapper(const struct arg *arg_p, struct sample *smp
SEND_ERR(stream->be, "Lua sample-fetch '%s': can't initialize Lua context.\n", fcn->name); SEND_ERR(stream->be, "Lua sample-fetch '%s': can't initialize Lua context.\n", fcn->name);
return 0; return 0;
} }
if (!hlua_ctx_init(stream->hlua, stream->task)) { if (!hlua_ctx_init(stream->hlua, stream->task, 0)) {
SEND_ERR(stream->be, "Lua sample-fetch '%s': can't initialize Lua context.\n", fcn->name); SEND_ERR(stream->be, "Lua sample-fetch '%s': can't initialize Lua context.\n", fcn->name);
return 0; return 0;
} }
@ -6777,7 +6790,7 @@ static enum act_return hlua_action(struct act_rule *rule, struct proxy *px,
rule->arg.hlua_rule->fcn.name); rule->arg.hlua_rule->fcn.name);
return ACT_RET_CONT; return ACT_RET_CONT;
} }
if (!hlua_ctx_init(s->hlua, s->task)) { if (!hlua_ctx_init(s->hlua, s->task, 0)) {
SEND_ERR(px, "Lua action '%s': can't initialize Lua context.\n", SEND_ERR(px, "Lua action '%s': can't initialize Lua context.\n",
rule->arg.hlua_rule->fcn.name); rule->arg.hlua_rule->fcn.name);
return ACT_RET_CONT; return ACT_RET_CONT;
@ -6971,7 +6984,7 @@ static int hlua_applet_tcp_init(struct appctx *ctx, struct proxy *px, struct str
* permits to save performances because a systematic * permits to save performances because a systematic
* Lua initialization cause 5% performances loss. * Lua initialization cause 5% performances loss.
*/ */
if (!hlua_ctx_init(hlua, task)) { if (!hlua_ctx_init(hlua, task, 0)) {
SEND_ERR(px, "Lua applet tcp '%s': can't initialize Lua context.\n", SEND_ERR(px, "Lua applet tcp '%s': can't initialize Lua context.\n",
ctx->rule->arg.hlua_rule->fcn.name); ctx->rule->arg.hlua_rule->fcn.name);
return 0; return 0;
@ -7178,7 +7191,7 @@ static int hlua_applet_http_init(struct appctx *ctx, struct proxy *px, struct st
* permits to save performances because a systematic * permits to save performances because a systematic
* Lua initialization cause 5% performances loss. * Lua initialization cause 5% performances loss.
*/ */
if (!hlua_ctx_init(hlua, task)) { if (!hlua_ctx_init(hlua, task, 0)) {
SEND_ERR(px, "Lua applet http '%s': can't initialize Lua context.\n", SEND_ERR(px, "Lua applet http '%s': can't initialize Lua context.\n",
ctx->rule->arg.hlua_rule->fcn.name); ctx->rule->arg.hlua_rule->fcn.name);
return 0; return 0;
@ -7932,7 +7945,7 @@ static int hlua_cli_parse_fct(char **args, char *payload, struct appctx *appctx,
appctx->ctx.hlua_cli.task->process = hlua_applet_wakeup; appctx->ctx.hlua_cli.task->process = hlua_applet_wakeup;
/* Initialises the Lua context */ /* Initialises the Lua context */
if (!hlua_ctx_init(hlua, appctx->ctx.hlua_cli.task)) { if (!hlua_ctx_init(hlua, appctx->ctx.hlua_cli.task, 0)) {
SEND_ERR(NULL, "Lua cli '%s': can't initialize Lua context.\n", fcn->name); SEND_ERR(NULL, "Lua cli '%s': can't initialize Lua context.\n", fcn->name);
goto error; goto error;
} }