Mercurial > hg > nginx
view src/core/ngx_file.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 | 1fdba317ee6d |
children | 9fd738b85fad |
line wrap: on
line source
/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #ifndef _NGX_FILE_H_INCLUDED_ #define _NGX_FILE_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> struct ngx_file_s { ngx_fd_t fd; ngx_str_t name; ngx_file_info_t info; off_t offset; off_t sys_offset; ngx_log_t *log; #if (NGX_THREADS) ngx_int_t (*thread_handler)(ngx_thread_task_t *task, ngx_file_t *file); void *thread_ctx; #endif #if (NGX_HAVE_FILE_AIO) ngx_event_aio_t *aio; #endif unsigned valid_info:1; unsigned directio:1; }; #define NGX_MAX_PATH_LEVEL 3 typedef time_t (*ngx_path_manager_pt) (void *data); typedef void (*ngx_path_loader_pt) (void *data); typedef struct { ngx_str_t name; size_t len; size_t level[3]; ngx_path_manager_pt manager; ngx_path_loader_pt loader; void *data; u_char *conf_file; ngx_uint_t line; } ngx_path_t; typedef struct { ngx_str_t name; size_t level[3]; } ngx_path_init_t; typedef struct { ngx_file_t file; off_t offset; ngx_path_t *path; ngx_pool_t *pool; char *warn; ngx_uint_t access; unsigned log_level:8; unsigned persistent:1; unsigned clean:1; } ngx_temp_file_t; typedef struct { ngx_uint_t access; ngx_uint_t path_access; time_t time; ngx_fd_t fd; unsigned create_path:1; unsigned delete_file:1; ngx_log_t *log; } ngx_ext_rename_file_t; typedef struct { off_t size; size_t buf_size; ngx_uint_t access; time_t time; ngx_log_t *log; } ngx_copy_file_t; typedef struct ngx_tree_ctx_s ngx_tree_ctx_t; typedef ngx_int_t (*ngx_tree_init_handler_pt) (void *ctx, void *prev); typedef ngx_int_t (*ngx_tree_handler_pt) (ngx_tree_ctx_t *ctx, ngx_str_t *name); struct ngx_tree_ctx_s { off_t size; off_t fs_size; ngx_uint_t access; time_t mtime; ngx_tree_init_handler_pt init_handler; ngx_tree_handler_pt file_handler; ngx_tree_handler_pt pre_tree_handler; ngx_tree_handler_pt post_tree_handler; ngx_tree_handler_pt spec_handler; void *data; size_t alloc; ngx_log_t *log; }; ngx_int_t ngx_get_full_name(ngx_pool_t *pool, ngx_str_t *prefix, ngx_str_t *name); ssize_t ngx_write_chain_to_temp_file(ngx_temp_file_t *tf, ngx_chain_t *chain); ngx_int_t ngx_create_temp_file(ngx_file_t *file, ngx_path_t *path, ngx_pool_t *pool, ngx_uint_t persistent, ngx_uint_t clean, ngx_uint_t access); void ngx_create_hashed_filename(ngx_path_t *path, u_char *file, size_t len); ngx_int_t ngx_create_path(ngx_file_t *file, ngx_path_t *path); ngx_err_t ngx_create_full_path(u_char *dir, ngx_uint_t access); ngx_int_t ngx_add_path(ngx_conf_t *cf, ngx_path_t **slot); ngx_int_t ngx_create_paths(ngx_cycle_t *cycle, ngx_uid_t user); ngx_int_t ngx_ext_rename_file(ngx_str_t *src, ngx_str_t *to, ngx_ext_rename_file_t *ext); ngx_int_t ngx_copy_file(u_char *from, u_char *to, ngx_copy_file_t *cf); ngx_int_t ngx_walk_tree(ngx_tree_ctx_t *ctx, ngx_str_t *tree); ngx_atomic_uint_t ngx_next_temp_number(ngx_uint_t collision); char *ngx_conf_set_path_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); char *ngx_conf_merge_path_value(ngx_conf_t *cf, ngx_path_t **path, ngx_path_t *prev, ngx_path_init_t *init); char *ngx_conf_set_access_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); extern ngx_atomic_t *ngx_temp_number; extern ngx_atomic_int_t ngx_random_number; #endif /* _NGX_FILE_H_INCLUDED_ */