Mercurial > hg > nginx
view src/core/ngx_open_file_cache.h @ 6351:497d0cff8ace
Resolver: fixed use-after-free memory accesses with CNAME.
When several requests were waiting for a response, then after getting
a CNAME response only the last request's context had the name updated.
Contexts of other requests had the wrong name. This name was used by
ngx_resolve_name_done() to find the node to remove the request context
from. When the name was wrong, the request could not be properly
cancelled, its context was freed but stayed linked to the node's waiting
list. This happened e.g. when the first request was aborted or timed
out before the resolving completed. When it completed, this triggered
a use-after-free memory access by calling ctx->handler of already freed
request context. The bug manifests itself by
"could not cancel <name> resolving" alerts in error_log.
When a request was responded with a CNAME, the request context kept
the pointer to the original node's rn->u.cname. If the original node
expired before the resolving timed out or completed with an error,
this would trigger a use-after-free memory access via ctx->name in
ctx->handler().
The fix is to keep ctx->name unmodified. The name from context
is no longer used by ngx_resolve_name_done(). Instead, we now keep
the pointer to resolver node to which this request is linked.
Keeping the original name intact also improves logging.
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Tue, 26 Jan 2016 16:46:59 +0300 |
parents | 47ece8818978 |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #ifndef _NGX_OPEN_FILE_CACHE_H_INCLUDED_ #define _NGX_OPEN_FILE_CACHE_H_INCLUDED_ #define NGX_OPEN_FILE_DIRECTIO_OFF NGX_MAX_OFF_T_VALUE typedef struct { ngx_fd_t fd; ngx_file_uniq_t uniq; time_t mtime; off_t size; off_t fs_size; off_t directio; size_t read_ahead; ngx_err_t err; char *failed; time_t valid; ngx_uint_t min_uses; #if (NGX_HAVE_OPENAT) size_t disable_symlinks_from; unsigned disable_symlinks:2; #endif unsigned test_dir:1; unsigned test_only:1; unsigned log:1; unsigned errors:1; unsigned events:1; unsigned is_dir:1; unsigned is_file:1; unsigned is_link:1; unsigned is_exec:1; unsigned is_directio:1; } ngx_open_file_info_t; typedef struct ngx_cached_open_file_s ngx_cached_open_file_t; struct ngx_cached_open_file_s { ngx_rbtree_node_t node; ngx_queue_t queue; u_char *name; time_t created; time_t accessed; ngx_fd_t fd; ngx_file_uniq_t uniq; time_t mtime; off_t size; ngx_err_t err; uint32_t uses; #if (NGX_HAVE_OPENAT) size_t disable_symlinks_from; unsigned disable_symlinks:2; #endif unsigned count:24; unsigned close:1; unsigned use_event:1; unsigned is_dir:1; unsigned is_file:1; unsigned is_link:1; unsigned is_exec:1; unsigned is_directio:1; ngx_event_t *event; }; typedef struct { ngx_rbtree_t rbtree; ngx_rbtree_node_t sentinel; ngx_queue_t expire_queue; ngx_uint_t current; ngx_uint_t max; time_t inactive; } ngx_open_file_cache_t; typedef struct { ngx_open_file_cache_t *cache; ngx_cached_open_file_t *file; ngx_uint_t min_uses; ngx_log_t *log; } ngx_open_file_cache_cleanup_t; typedef struct { /* ngx_connection_t stub to allow use c->fd as event ident */ void *data; ngx_event_t *read; ngx_event_t *write; ngx_fd_t fd; ngx_cached_open_file_t *file; ngx_open_file_cache_t *cache; } ngx_open_file_cache_event_t; ngx_open_file_cache_t *ngx_open_file_cache_init(ngx_pool_t *pool, ngx_uint_t max, time_t inactive); ngx_int_t ngx_open_cached_file(ngx_open_file_cache_t *cache, ngx_str_t *name, ngx_open_file_info_t *of, ngx_pool_t *pool); #endif /* _NGX_OPEN_FILE_CACHE_H_INCLUDED_ */