Mercurial > hg > nginx
annotate src/core/ngx_rwlock.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 | d1816a2696de |
| children | 7752d8523066 |
| rev | line source |
|---|---|
| 6101 | 1 |
| 2 /* | |
| 3 * Copyright (C) Ruslan Ermilov | |
| 4 * Copyright (C) Nginx, Inc. | |
| 5 */ | |
| 6 | |
| 7 | |
| 8 #include <ngx_config.h> | |
| 9 #include <ngx_core.h> | |
| 10 | |
| 11 | |
| 12 #if (NGX_HAVE_ATOMIC_OPS) | |
| 13 | |
| 14 | |
| 15 #define NGX_RWLOCK_SPIN 2048 | |
| 16 #define NGX_RWLOCK_WLOCK ((ngx_atomic_uint_t) -1) | |
| 17 | |
| 18 | |
| 19 void | |
| 20 ngx_rwlock_wlock(ngx_atomic_t *lock) | |
| 21 { | |
| 22 ngx_uint_t i, n; | |
| 23 | |
| 24 for ( ;; ) { | |
| 25 | |
| 26 if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, NGX_RWLOCK_WLOCK)) { | |
| 27 return; | |
| 28 } | |
| 29 | |
| 30 if (ngx_ncpu > 1) { | |
| 31 | |
| 32 for (n = 1; n < NGX_RWLOCK_SPIN; n <<= 1) { | |
| 33 | |
| 34 for (i = 0; i < n; i++) { | |
| 35 ngx_cpu_pause(); | |
| 36 } | |
| 37 | |
| 38 if (*lock == 0 | |
| 39 && ngx_atomic_cmp_set(lock, 0, NGX_RWLOCK_WLOCK)) | |
| 40 { | |
| 41 return; | |
| 42 } | |
| 43 } | |
| 44 } | |
| 45 | |
| 46 ngx_sched_yield(); | |
| 47 } | |
| 48 } | |
| 49 | |
| 50 | |
| 51 void | |
| 52 ngx_rwlock_rlock(ngx_atomic_t *lock) | |
| 53 { | |
| 54 ngx_uint_t i, n; | |
| 55 ngx_atomic_uint_t readers; | |
| 56 | |
| 57 for ( ;; ) { | |
| 58 readers = *lock; | |
| 59 | |
| 60 if (readers != NGX_RWLOCK_WLOCK | |
| 61 && ngx_atomic_cmp_set(lock, readers, readers + 1)) | |
| 62 { | |
| 63 return; | |
| 64 } | |
| 65 | |
| 66 if (ngx_ncpu > 1) { | |
| 67 | |
| 68 for (n = 1; n < NGX_RWLOCK_SPIN; n <<= 1) { | |
| 69 | |
| 70 for (i = 0; i < n; i++) { | |
| 71 ngx_cpu_pause(); | |
| 72 } | |
| 73 | |
| 74 readers = *lock; | |
| 75 | |
| 76 if (readers != NGX_RWLOCK_WLOCK | |
| 77 && ngx_atomic_cmp_set(lock, readers, readers + 1)) | |
| 78 { | |
| 79 return; | |
| 80 } | |
| 81 } | |
| 82 } | |
| 83 | |
| 84 ngx_sched_yield(); | |
| 85 } | |
| 86 } | |
| 87 | |
| 88 | |
| 89 void | |
| 90 ngx_rwlock_unlock(ngx_atomic_t *lock) | |
| 91 { | |
| 92 ngx_atomic_uint_t readers; | |
| 93 | |
| 94 readers = *lock; | |
| 95 | |
| 96 if (readers == NGX_RWLOCK_WLOCK) { | |
|
7037
12efcdcb8a4b
Added memory barrier semantics to ngx_rwlock_unlock().
Ruslan Ermilov <ru@nginx.com>
parents:
6270
diff
changeset
|
97 (void) ngx_atomic_cmp_set(lock, NGX_RWLOCK_WLOCK, 0); |
| 6101 | 98 return; |
| 99 } | |
| 100 | |
| 101 for ( ;; ) { | |
| 102 | |
| 103 if (ngx_atomic_cmp_set(lock, readers, readers - 1)) { | |
| 104 return; | |
| 105 } | |
| 106 | |
| 107 readers = *lock; | |
| 108 } | |
| 109 } | |
| 110 | |
| 111 | |
|
7038
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
112 void |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
113 ngx_rwlock_downgrade(ngx_atomic_t *lock) |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
114 { |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
115 if (*lock == NGX_RWLOCK_WLOCK) { |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
116 *lock = 1; |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
117 } |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
118 } |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
119 |
|
d1816a2696de
Introduced ngx_rwlock_downgrade().
Ruslan Ermilov <ru@nginx.com>
parents:
7037
diff
changeset
|
120 |
|
6103
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
121 #else |
|
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
122 |
|
6270
e769cc88f996
Core: read/write locks are also required by the Stream module.
Piotr Sikora <piotrsikora@google.com>
parents:
6103
diff
changeset
|
123 #if (NGX_HTTP_UPSTREAM_ZONE || NGX_STREAM_UPSTREAM_ZONE) |
|
6103
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
124 |
|
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
125 #error ngx_atomic_cmp_set() is not defined! |
|
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
126 |
| 6101 | 127 #endif |
|
6103
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
128 |
|
79ddb0bdb273
Upstream: the "zone" directive.
Ruslan Ermilov <ru@nginx.com>
parents:
6101
diff
changeset
|
129 #endif |