From d25139db01b636a8212c13e1feeca37eaadad0b5 Mon Sep 17 00:00:00 2001 From: Sergey Kandaurov Date: Tue, 11 Feb 2025 22:54:04 +0400 Subject: Improved ngx_http_subrequest() error handling. Previously, request might be left in inconsistent state in case of error, which manifested in "http request count is zero" alerts when used by SSI filter. The fix is to reshuffle initialization order to postpone committing state changes until after any potentially failing parts. Found by bad memory allocator simulation. --- src/http/ngx_http_core_module.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c index a1540c018..92c3eae8a 100644 --- a/src/http/ngx_http_core_module.c +++ b/src/http/ngx_http_core_module.c @@ -2327,6 +2327,7 @@ ngx_http_subrequest(ngx_http_request_t *r, ngx_connection_t *c; ngx_http_request_t *sr; ngx_http_core_srv_conf_t *cscf; + ngx_http_posted_request_t *posted; ngx_http_postponed_request_t *pr, *p; if (r->subrequests == 0) { @@ -2380,6 +2381,11 @@ ngx_http_subrequest(ngx_http_request_t *r, return NGX_ERROR; } + posted = ngx_palloc(r->pool, sizeof(ngx_http_posted_request_t)); + if (posted == NULL) { + return NGX_ERROR; + } + cscf = ngx_http_get_module_srv_conf(r, ngx_http_core_module); sr->main_conf = cscf->ctx->main_conf; sr->srv_conf = cscf->ctx->srv_conf; @@ -2438,10 +2444,6 @@ ngx_http_subrequest(ngx_http_request_t *r, } if (!sr->background) { - if (c->data == r && r->postponed == NULL) { - c->data = sr; - } - pr = ngx_palloc(r->pool, sizeof(ngx_http_postponed_request_t)); if (pr == NULL) { return NGX_ERROR; @@ -2451,6 +2453,10 @@ ngx_http_subrequest(ngx_http_request_t *r, pr->out = NULL; pr->next = NULL; + if (c->data == r && r->postponed == NULL) { + c->data = sr; + } + if (r->postponed) { for (p = r->postponed; p->next; p = p->next) { /* void */ } p->next = pr; @@ -2498,7 +2504,7 @@ ngx_http_subrequest(ngx_http_request_t *r, ngx_http_update_location_config(sr); } - return ngx_http_post_request(sr, NULL); + return ngx_http_post_request(sr, posted); } -- cgit v1.2.3