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Fix possible race in isc__nm_tcpconnect.

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There's a possibility of race in isc__nm_tcpconnect if the asynchronous
connect operation finishes with all the callbacks before we exit the
isc__nm_tcpconnect itself we might access an already freed memory.
Fix it by creating an additional reference to the socket freed at the
end of isc__nm_tcpconnect.

(cherry picked from commit 896db0f419)
This commit is contained in:
Witold Kręcicki 2020-06-29 08:43:54 +02:00 committed by Ondřej Surý
parent ebb4d506d6
commit 5a0fbc41ec
1 changed files with 12 additions and 4 deletions
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16
lib/isc/netmgr/tcp.c
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@ -195,9 +195,10 @@ tcp_connect_cb(uv_connect_t *uvreq, int status) {
isc_result_t
isc_nm_tcpconnect(isc_nm_t *mgr, isc_nmiface_t *local, isc_nmiface_t *peer,
isc_nm_cb_t cb, void *cbarg, size_t extrahandlesize) {
isc_nmsocket_t *nsock = NULL;
isc_nmsocket_t *nsock = NULL, *tmp = NULL;
isc__netievent_tcpconnect_t *ievent = NULL;
isc__nm_uvreq_t *req = NULL;
isc_result_t result = ISC_R_SUCCESS;
REQUIRE(VALID_NM(mgr));
@ -215,6 +216,12 @@ isc_nm_tcpconnect(isc_nm_t *mgr, isc_nmiface_t *local, isc_nmiface_t *peer,
ievent->sock = nsock;
ievent->req = req;
/*
* Async callbacks can dereference the socket in the meantime,
* we need to hold an additional reference to it.
*/
isc__nmsocket_attach(nsock, &tmp);
if (isc__nm_in_netthread()) {
nsock->tid = isc_nm_tid();
isc__nm_async_tcpconnect(&mgr->workers[nsock->tid],
@ -234,12 +241,13 @@ isc_nm_tcpconnect(isc_nm_t *mgr, isc_nmiface_t *local, isc_nmiface_t *peer,
}
if (nsock->result != ISC_R_SUCCESS) {
isc_result_t result = nsock->result;
result = nsock->result;
isc__nmsocket_detach(&nsock);
return (result);
}
return (ISC_R_SUCCESS);
isc__nmsocket_detach(&tmp);
return (result);
}
isc_result_t