Mercurial > hg > nginx
view src/http/ngx_http_postpone_filter_module.c @ 7674:7731c710796f
Memcached: protect from too long responses.
If a memcached response was followed by a correct trailer, and then
the NUL character followed by some extra data - this was accepted by
the trailer checking code. This in turn resulted in ctx->rest underflow
and caused negative size buffer on the next reading from the upstream,
followed by the "negative size buf in writer" alert.
Fix is to always check for too long responses, so a correct trailer cannot
be followed by extra data.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Mon, 06 Jul 2020 18:36:17 +0300 |
parents | 43585e0e12a3 |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> static ngx_int_t ngx_http_postpone_filter_add(ngx_http_request_t *r, ngx_chain_t *in); static ngx_int_t ngx_http_postpone_filter_in_memory(ngx_http_request_t *r, ngx_chain_t *in); static ngx_int_t ngx_http_postpone_filter_init(ngx_conf_t *cf); static ngx_http_module_t ngx_http_postpone_filter_module_ctx = { NULL, /* preconfiguration */ ngx_http_postpone_filter_init, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ NULL, /* create location configuration */ NULL /* merge location configuration */ }; ngx_module_t ngx_http_postpone_filter_module = { NGX_MODULE_V1, &ngx_http_postpone_filter_module_ctx, /* module context */ NULL, /* module directives */ NGX_HTTP_MODULE, /* module type */ NULL, /* init master */ NULL, /* init module */ NULL, /* init process */ NULL, /* init thread */ NULL, /* exit thread */ NULL, /* exit process */ NULL, /* exit master */ NGX_MODULE_V1_PADDING }; static ngx_http_output_body_filter_pt ngx_http_next_body_filter; static ngx_int_t ngx_http_postpone_filter(ngx_http_request_t *r, ngx_chain_t *in) { ngx_connection_t *c; ngx_http_postponed_request_t *pr; c = r->connection; ngx_log_debug3(NGX_LOG_DEBUG_HTTP, c->log, 0, "http postpone filter \"%V?%V\" %p", &r->uri, &r->args, in); if (r->subrequest_in_memory) { return ngx_http_postpone_filter_in_memory(r, in); } if (r != c->data) { if (in) { if (ngx_http_postpone_filter_add(r, in) != NGX_OK) { return NGX_ERROR; } return NGX_OK; } #if 0 /* TODO: SSI may pass NULL */ ngx_log_error(NGX_LOG_ALERT, c->log, 0, "http postpone filter NULL inactive request"); #endif return NGX_OK; } if (r->postponed == NULL) { if (in || c->buffered) { return ngx_http_next_body_filter(r->main, in); } return NGX_OK; } if (in) { if (ngx_http_postpone_filter_add(r, in) != NGX_OK) { return NGX_ERROR; } } do { pr = r->postponed; if (pr->request) { ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0, "http postpone filter wake \"%V?%V\"", &pr->request->uri, &pr->request->args); r->postponed = pr->next; c->data = pr->request; return ngx_http_post_request(pr->request, NULL); } if (pr->out == NULL) { ngx_log_error(NGX_LOG_ALERT, c->log, 0, "http postpone filter NULL output"); } else { ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0, "http postpone filter output \"%V?%V\"", &r->uri, &r->args); if (ngx_http_next_body_filter(r->main, pr->out) == NGX_ERROR) { return NGX_ERROR; } } r->postponed = pr->next; } while (r->postponed); return NGX_OK; } static ngx_int_t ngx_http_postpone_filter_add(ngx_http_request_t *r, ngx_chain_t *in) { ngx_http_postponed_request_t *pr, **ppr; if (r->postponed) { for (pr = r->postponed; pr->next; pr = pr->next) { /* void */ } if (pr->request == NULL) { goto found; } ppr = &pr->next; } else { ppr = &r->postponed; } pr = ngx_palloc(r->pool, sizeof(ngx_http_postponed_request_t)); if (pr == NULL) { return NGX_ERROR; } *ppr = pr; pr->request = NULL; pr->out = NULL; pr->next = NULL; found: if (ngx_chain_add_copy(r->pool, &pr->out, in) == NGX_OK) { return NGX_OK; } return NGX_ERROR; } static ngx_int_t ngx_http_postpone_filter_in_memory(ngx_http_request_t *r, ngx_chain_t *in) { size_t len; ngx_buf_t *b; ngx_connection_t *c; ngx_http_core_loc_conf_t *clcf; c = r->connection; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http postpone filter in memory"); if (r->out == NULL) { clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module); if (r->headers_out.content_length_n != -1) { len = r->headers_out.content_length_n; if (len > clcf->subrequest_output_buffer_size) { ngx_log_error(NGX_LOG_ERR, c->log, 0, "too big subrequest response: %uz", len); return NGX_ERROR; } } else { len = clcf->subrequest_output_buffer_size; } b = ngx_create_temp_buf(r->pool, len); if (b == NULL) { return NGX_ERROR; } b->last_buf = 1; r->out = ngx_alloc_chain_link(r->pool); if (r->out == NULL) { return NGX_ERROR; } r->out->buf = b; r->out->next = NULL; } b = r->out->buf; for ( /* void */ ; in; in = in->next) { if (ngx_buf_special(in->buf)) { continue; } len = in->buf->last - in->buf->pos; if (len > (size_t) (b->end - b->last)) { ngx_log_error(NGX_LOG_ERR, c->log, 0, "too big subrequest response"); return NGX_ERROR; } ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0, "http postpone filter in memory %uz bytes", len); b->last = ngx_cpymem(b->last, in->buf->pos, len); in->buf->pos = in->buf->last; } return NGX_OK; } static ngx_int_t ngx_http_postpone_filter_init(ngx_conf_t *cf) { ngx_http_next_body_filter = ngx_http_top_body_filter; ngx_http_top_body_filter = ngx_http_postpone_filter; return NGX_OK; }