Mercurial > hg > nginx
view src/core/ngx_hash.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 | d620f497c50f |
children | f8f6b9fee66a |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #ifndef _NGX_HASH_H_INCLUDED_ #define _NGX_HASH_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> typedef struct { void *value; u_short len; u_char name[1]; } ngx_hash_elt_t; typedef struct { ngx_hash_elt_t **buckets; ngx_uint_t size; } ngx_hash_t; typedef struct { ngx_hash_t hash; void *value; } ngx_hash_wildcard_t; typedef struct { ngx_str_t key; ngx_uint_t key_hash; void *value; } ngx_hash_key_t; typedef ngx_uint_t (*ngx_hash_key_pt) (u_char *data, size_t len); typedef struct { ngx_hash_t hash; ngx_hash_wildcard_t *wc_head; ngx_hash_wildcard_t *wc_tail; } ngx_hash_combined_t; typedef struct { ngx_hash_t *hash; ngx_hash_key_pt key; ngx_uint_t max_size; ngx_uint_t bucket_size; char *name; ngx_pool_t *pool; ngx_pool_t *temp_pool; } ngx_hash_init_t; #define NGX_HASH_SMALL 1 #define NGX_HASH_LARGE 2 #define NGX_HASH_LARGE_ASIZE 16384 #define NGX_HASH_LARGE_HSIZE 10007 #define NGX_HASH_WILDCARD_KEY 1 #define NGX_HASH_READONLY_KEY 2 typedef struct { ngx_uint_t hsize; ngx_pool_t *pool; ngx_pool_t *temp_pool; ngx_array_t keys; ngx_array_t *keys_hash; ngx_array_t dns_wc_head; ngx_array_t *dns_wc_head_hash; ngx_array_t dns_wc_tail; ngx_array_t *dns_wc_tail_hash; } ngx_hash_keys_arrays_t; typedef struct { ngx_uint_t hash; ngx_str_t key; ngx_str_t value; u_char *lowcase_key; } ngx_table_elt_t; void *ngx_hash_find(ngx_hash_t *hash, ngx_uint_t key, u_char *name, size_t len); void *ngx_hash_find_wc_head(ngx_hash_wildcard_t *hwc, u_char *name, size_t len); void *ngx_hash_find_wc_tail(ngx_hash_wildcard_t *hwc, u_char *name, size_t len); void *ngx_hash_find_combined(ngx_hash_combined_t *hash, ngx_uint_t key, u_char *name, size_t len); ngx_int_t ngx_hash_init(ngx_hash_init_t *hinit, ngx_hash_key_t *names, ngx_uint_t nelts); ngx_int_t ngx_hash_wildcard_init(ngx_hash_init_t *hinit, ngx_hash_key_t *names, ngx_uint_t nelts); #define ngx_hash(key, c) ((ngx_uint_t) key * 31 + c) ngx_uint_t ngx_hash_key(u_char *data, size_t len); ngx_uint_t ngx_hash_key_lc(u_char *data, size_t len); ngx_uint_t ngx_hash_strlow(u_char *dst, u_char *src, size_t n); ngx_int_t ngx_hash_keys_array_init(ngx_hash_keys_arrays_t *ha, ngx_uint_t type); ngx_int_t ngx_hash_add_key(ngx_hash_keys_arrays_t *ha, ngx_str_t *key, void *value, ngx_uint_t flags); #endif /* _NGX_HASH_H_INCLUDED_ */