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Hold qid->lock when calling deref_portentry() as

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socket_search() need portentry to be unchanging.

    WARNING: ThreadSanitizer: data race
    Write of size 8 at 0x000000000001 by thread T1 (mutexes: write M1):
    #0 deref_portentry lib/dns/dispatch.c:630
    #1 deactivate_dispsocket lib/dns/dispatch.c:861
    #2 udp_recv lib/dns/dispatch.c:1105
    #3 udp_exrecv lib/dns/dispatch.c:1028
    #4 dispatch lib/isc/task.c:1152
    #5 run lib/isc/task.c:1344
    #6 <null> <null>

    Previous read of size 8 at 0x000000000001 by thread T2 (mutexes: write M1, write M2):
    #0 socket_search lib/dns/dispatch.c:661
    #1 get_dispsocket lib/dns/dispatch.c:744
    #2 dns_dispatch_addresponse lib/dns/dispatch.c:3120
    #3 resquery_send lib/dns/resolver.c:2467
    #4 fctx_query lib/dns/resolver.c:2217
    #5 fctx_try lib/dns/resolver.c:4245
    #6 fctx_timeout lib/dns/resolver.c:4570
    #7 dispatch lib/isc/task.c:1152
    #8 run lib/isc/task.c:1344
    #9 <null> <null>
This commit is contained in:
Mark Andrews 2020-10-22 16:13:06 +11:00
parent 399cc3ebdf
commit 5c253c416d
1 changed files with 10 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

20
lib/dns/dispatch.c
View file

@ -619,11 +619,10 @@ new_portentry(dns_dispatch_t *disp, in_port_t port) {
}
/*%
* The caller must not hold the qid->lock.
* The caller must hold the qid->lock.
*/
static void
deref_portentry(dns_dispatch_t *disp, dispportentry_t **portentryp) {
dns_qid_t *qid;
dispportentry_t *portentry = *portentryp;
*portentryp = NULL;
@ -631,13 +630,10 @@ deref_portentry(dns_dispatch_t *disp, dispportentry_t **portentryp) {
REQUIRE(portentry != NULL);
if (isc_refcount_decrement(&portentry->refs) == 1) {
qid = DNS_QID(disp);
LOCK(&qid->lock);
ISC_LIST_UNLINK(disp->port_table[portentry->port %
DNS_DISPATCH_PORTTABLESIZE],
portentry, link);
isc_mempool_put(disp->portpool, portentry);
UNLOCK(&qid->lock);
}
}
@ -777,9 +773,9 @@ get_dispsocket(dns_dispatch_t *disp, const isc_sockaddr_t *dest,
if (result == ISC_R_SUCCESS) {
dispsock->socket = sock;
dispsock->host = *dest;
dispsock->portentry = portentry;
dispsock->bucket = bucket;
LOCK(&qid->lock);
dispsock->portentry = portentry;
ISC_LIST_APPEND(qid->sock_table[bucket], dispsock, blink);
UNLOCK(&qid->lock);
*dispsockp = dispsock;
@ -805,7 +801,7 @@ get_dispsocket(dns_dispatch_t *disp, const isc_sockaddr_t *dest,
static void
destroy_dispsocket(dns_dispatch_t *disp, dispsocket_t **dispsockp) {
dispsocket_t *dispsock;
dns_qid_t *qid;
dns_qid_t *qid = DNS_QID(disp);
/*
* The dispatch must be locked.
@ -819,13 +815,15 @@ destroy_dispsocket(dns_dispatch_t *disp, dispsocket_t **dispsockp) {
disp->nsockets--;
dispsock->magic = 0;
if (dispsock->portentry != NULL) {
/* socket_search() tests and dereferences portentry. */
LOCK(&qid->lock);
deref_portentry(disp, &dispsock->portentry);
UNLOCK(&qid->lock);
}
if (dispsock->socket != NULL) {
isc_socket_detach(&dispsock->socket);
}
if (ISC_LINK_LINKED(dispsock, blink)) {
qid = DNS_QID(disp);
LOCK(&qid->lock);
ISC_LIST_UNLINK(qid->sock_table[dispsock->bucket], dispsock,
blink);
@ -844,7 +842,7 @@ destroy_dispsocket(dns_dispatch_t *disp, dispsocket_t **dispsockp) {
static void
deactivate_dispsocket(dns_dispatch_t *disp, dispsocket_t *dispsock) {
isc_result_t result;
dns_qid_t *qid;
dns_qid_t *qid = DNS_QID(disp);
/*
* The dispatch must be locked.
@ -856,14 +854,16 @@ deactivate_dispsocket(dns_dispatch_t *disp, dispsocket_t *dispsock) {
}
INSIST(dispsock->portentry != NULL);
/* socket_search() tests and dereferences portentry. */
LOCK(&qid->lock);
deref_portentry(disp, &dispsock->portentry);
UNLOCK(&qid->lock);
if (disp->nsockets > DNS_DISPATCH_POOLSOCKS) {
destroy_dispsocket(disp, &dispsock);
} else {
result = isc_socket_close(dispsock->socket);
qid = DNS_QID(disp);
LOCK(&qid->lock);
ISC_LIST_UNLINK(qid->sock_table[dispsock->bucket], dispsock,
blink);