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* For retriggering a DNS lookup worker->cp->addr should be set to NULL and thus

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we need to avoid a race that worker->cp->addr switches to NULL after we
  checked it to be non NULL but before we assign it to conn->addr in an else
  tree which would leave conn->addr to NULL and likely cause a segfault later.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1909400 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Ruediger Pluem
2023-04-25 11:52:17 +00:00
parent f3825febe8
commit dc498e9fde
1 changed files with 12 additions and 6 deletions
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18
modules/proxy/proxy_util.c
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@@ -2761,8 +2761,16 @@ ap_proxy_determine_connection(apr_pool_t *p, request_rec *r,
/* /*
* Looking up the backend address for the worker only makes sense if * Looking up the backend address for the worker only makes sense if
* we can reuse the address. * we can reuse the address.
*
* As we indicate in the comment below that for retriggering a DNS
* lookup worker->cp->addr should be set to NULL we need to avoid
* a race that worker->cp->addr switches to NULL after we checked
* it to be non NULL but before we assign it to conn->addr in an
* else tree which would leave it to NULL and likely cause a
* segfault later.
*/ */
if (!worker->cp->addr) { conn->addr = worker->cp->addr;
if (!conn->addr) {
if ((err = PROXY_THREAD_LOCK(worker)) != APR_SUCCESS) { if ((err = PROXY_THREAD_LOCK(worker)) != APR_SUCCESS) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, err, r, APLOGNO(00945) "lock"); ap_log_rerror(APLOG_MARK, APLOG_ERR, err, r, APLOGNO(00945) "lock");
return HTTP_INTERNAL_SERVER_ERROR; return HTTP_INTERNAL_SERVER_ERROR;
@@ -2772,7 +2780,8 @@ ap_proxy_determine_connection(apr_pool_t *p, request_rec *r,
* Recheck addr after we got the lock. This may have changed * Recheck addr after we got the lock. This may have changed
* while waiting for the lock. * while waiting for the lock.
*/ */
if (!AP_VOLATILIZE_T(apr_sockaddr_t *, worker->cp->addr)) { conn->addr = AP_VOLATILIZE_T(apr_sockaddr_t *, worker->cp->addr);
if (!conn->addr) {
apr_sockaddr_t *addr; apr_sockaddr_t *addr;
@@ -2786,16 +2795,13 @@ ap_proxy_determine_connection(apr_pool_t *p, request_rec *r,
conn->hostname, APR_UNSPEC, conn->hostname, APR_UNSPEC,
conn->port, 0, conn->port, 0,
worker->cp->dns_pool); worker->cp->dns_pool);
conn->addr = addr;
worker->cp->addr = addr; worker->cp->addr = addr;
} }
conn->addr = worker->cp->addr;
if ((uerr = PROXY_THREAD_UNLOCK(worker)) != APR_SUCCESS) { if ((uerr = PROXY_THREAD_UNLOCK(worker)) != APR_SUCCESS) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, uerr, r, APLOGNO(00946) "unlock"); ap_log_rerror(APLOG_MARK, APLOG_ERR, uerr, r, APLOGNO(00946) "unlock");
} }
} }
else {
conn->addr = worker->cp->addr;
}
} }
} }
/* Close a possible existing socket if we are told to do so */ /* Close a possible existing socket if we are told to do so */