Mercurial > hg > nginx-quic
annotate src/core/ngx_shmtx.h @ 6359:dac6eda40475 stable-1.8
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> |
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date | Tue, 26 Jan 2016 16:46:59 +0300 |
parents | 512c741fa841 |
children |
rev | line source |
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611 | 1 |
2 /* | |
3 * Copyright (C) Igor Sysoev | |
4412 | 4 * Copyright (C) Nginx, Inc. |
611 | 5 */ |
6 | |
7 | |
8 #ifndef _NGX_SHMTX_H_INCLUDED_ | |
9 #define _NGX_SHMTX_H_INCLUDED_ | |
10 | |
11 | |
12 #include <ngx_config.h> | |
13 #include <ngx_core.h> | |
14 | |
15 | |
16 typedef struct { | |
4309
3f6040cd731e
Added shmtx interface to forcibly unlock mutexes.
Maxim Dounin <mdounin@mdounin.ru>
parents:
3909
diff
changeset
|
17 ngx_atomic_t lock; |
3f6040cd731e
Added shmtx interface to forcibly unlock mutexes.
Maxim Dounin <mdounin@mdounin.ru>
parents:
3909
diff
changeset
|
18 #if (NGX_HAVE_POSIX_SEM) |
3f6040cd731e
Added shmtx interface to forcibly unlock mutexes.
Maxim Dounin <mdounin@mdounin.ru>
parents:
3909
diff
changeset
|
19 ngx_atomic_t wait; |
3f6040cd731e
Added shmtx interface to forcibly unlock mutexes.
Maxim Dounin <mdounin@mdounin.ru>
parents:
3909
diff
changeset
|
20 #endif |
3f6040cd731e
Added shmtx interface to forcibly unlock mutexes.
Maxim Dounin <mdounin@mdounin.ru>
parents:
3909
diff
changeset
|
21 } ngx_shmtx_sh_t; |
3f6040cd731e
Added shmtx interface to forcibly unlock mutexes.
Maxim Dounin <mdounin@mdounin.ru>
parents:
3909
diff
changeset
|
22 |
3f6040cd731e
Added shmtx interface to forcibly unlock mutexes.
Maxim Dounin <mdounin@mdounin.ru>
parents:
3909
diff
changeset
|
23 |
3f6040cd731e
Added shmtx interface to forcibly unlock mutexes.
Maxim Dounin <mdounin@mdounin.ru>
parents:
3909
diff
changeset
|
24 typedef struct { |
611 | 25 #if (NGX_HAVE_ATOMIC_OPS) |
26 ngx_atomic_t *lock; | |
3909
0daede16d68b
use POSIX semaphores in shmtx instead of sched_yield()
Igor Sysoev <igor@sysoev.ru>
parents:
2563
diff
changeset
|
27 #if (NGX_HAVE_POSIX_SEM) |
4309
3f6040cd731e
Added shmtx interface to forcibly unlock mutexes.
Maxim Dounin <mdounin@mdounin.ru>
parents:
3909
diff
changeset
|
28 ngx_atomic_t *wait; |
3909
0daede16d68b
use POSIX semaphores in shmtx instead of sched_yield()
Igor Sysoev <igor@sysoev.ru>
parents:
2563
diff
changeset
|
29 ngx_uint_t semaphore; |
0daede16d68b
use POSIX semaphores in shmtx instead of sched_yield()
Igor Sysoev <igor@sysoev.ru>
parents:
2563
diff
changeset
|
30 sem_t sem; |
0daede16d68b
use POSIX semaphores in shmtx instead of sched_yield()
Igor Sysoev <igor@sysoev.ru>
parents:
2563
diff
changeset
|
31 #endif |
611 | 32 #else |
33 ngx_fd_t fd; | |
34 u_char *name; | |
35 #endif | |
3909
0daede16d68b
use POSIX semaphores in shmtx instead of sched_yield()
Igor Sysoev <igor@sysoev.ru>
parents:
2563
diff
changeset
|
36 ngx_uint_t spin; |
611 | 37 } ngx_shmtx_t; |
38 | |
39 | |
4309
3f6040cd731e
Added shmtx interface to forcibly unlock mutexes.
Maxim Dounin <mdounin@mdounin.ru>
parents:
3909
diff
changeset
|
40 ngx_int_t ngx_shmtx_create(ngx_shmtx_t *mtx, ngx_shmtx_sh_t *addr, |
3f6040cd731e
Added shmtx interface to forcibly unlock mutexes.
Maxim Dounin <mdounin@mdounin.ru>
parents:
3909
diff
changeset
|
41 u_char *name); |
4738
512c741fa841
Fixed typo in a function name.
Ruslan Ermilov <ru@nginx.com>
parents:
4412
diff
changeset
|
42 void ngx_shmtx_destroy(ngx_shmtx_t *mtx); |
3909
0daede16d68b
use POSIX semaphores in shmtx instead of sched_yield()
Igor Sysoev <igor@sysoev.ru>
parents:
2563
diff
changeset
|
43 ngx_uint_t ngx_shmtx_trylock(ngx_shmtx_t *mtx); |
0daede16d68b
use POSIX semaphores in shmtx instead of sched_yield()
Igor Sysoev <igor@sysoev.ru>
parents:
2563
diff
changeset
|
44 void ngx_shmtx_lock(ngx_shmtx_t *mtx); |
0daede16d68b
use POSIX semaphores in shmtx instead of sched_yield()
Igor Sysoev <igor@sysoev.ru>
parents:
2563
diff
changeset
|
45 void ngx_shmtx_unlock(ngx_shmtx_t *mtx); |
4309
3f6040cd731e
Added shmtx interface to forcibly unlock mutexes.
Maxim Dounin <mdounin@mdounin.ru>
parents:
3909
diff
changeset
|
46 ngx_uint_t ngx_shmtx_force_unlock(ngx_shmtx_t *mtx, ngx_pid_t pid); |
611 | 47 |
48 | |
49 #endif /* _NGX_SHMTX_H_INCLUDED_ */ |