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util/vhost-user-server: fix memory leak in vu_message_read()

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fds[] is leaked when qio_channel_readv_full() fails.

Use vmsg->fds[] instead of keeping a local fds[] array. Then we can
reuse goto fail to clean up fds. vmsg->fd_num must be zeroed before the
loop to make this safe.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200924151549.913737-8-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2020-09-24 16:15:43 +01:00
parent 47ba680466
commit 8c7f7cbca0
1 changed files with 28 additions and 32 deletions
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60
util/vhost-user-server.c
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@ -100,21 +100,11 @@ vu_message_read(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
};
int rc, read_bytes = 0;
Error *local_err = NULL;
/*
* Store fds/nfds returned from qio_channel_readv_full into
* temporary variables.
*
* VhostUserMsg is a packed structure, gcc will complain about passing
* pointer to a packed structure member if we pass &VhostUserMsg.fd_num
* and &VhostUserMsg.fds directly when calling qio_channel_readv_full,
* thus two temporary variables nfds and fds are used here.
*/
size_t nfds = 0, nfds_t = 0;
const size_t max_fds = G_N_ELEMENTS(vmsg->fds);
int *fds_t = NULL;
VuServer *server = container_of(vu_dev, VuServer, vu_dev);
QIOChannel *ioc = server->ioc;
vmsg->fd_num = 0;
if (!ioc) {
error_report_err(local_err);
goto fail;
@ -122,41 +112,47 @@ vu_message_read(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
assert(qemu_in_coroutine());
do {
size_t nfds = 0;
int *fds = NULL;
/*
* qio_channel_readv_full may have short reads, keeping calling it
* until getting VHOST_USER_HDR_SIZE or 0 bytes in total
*/
rc = qio_channel_readv_full(ioc, &iov, 1, &fds_t, &nfds_t, &local_err);
rc = qio_channel_readv_full(ioc, &iov, 1, &fds, &nfds, &local_err);
if (rc < 0) {
if (rc == QIO_CHANNEL_ERR_BLOCK) {
assert(local_err == NULL);
qio_channel_yield(ioc, G_IO_IN);
continue;
} else {
error_report_err(local_err);
return false;
}
}
read_bytes += rc;
if (nfds_t > 0) {
if (nfds + nfds_t > max_fds) {
error_report("A maximum of %zu fds are allowed, "
"however got %zu fds now",
max_fds, nfds + nfds_t);
goto fail;
}
memcpy(vmsg->fds + nfds, fds_t,
nfds_t *sizeof(vmsg->fds[0]));
nfds += nfds_t;
g_free(fds_t);
}
if (read_bytes == VHOST_USER_HDR_SIZE || rc == 0) {
break;
}
iov.iov_base = (char *)vmsg + read_bytes;
iov.iov_len = VHOST_USER_HDR_SIZE - read_bytes;
} while (true);
vmsg->fd_num = nfds;
if (nfds > 0) {
if (vmsg->fd_num + nfds > max_fds) {
error_report("A maximum of %zu fds are allowed, "
"however got %zu fds now",
max_fds, vmsg->fd_num + nfds);
g_free(fds);
goto fail;
}
memcpy(vmsg->fds + vmsg->fd_num, fds, nfds * sizeof(vmsg->fds[0]));
vmsg->fd_num += nfds;
g_free(fds);
}
if (rc == 0) { /* socket closed */
goto fail;
}
iov.iov_base += rc;
iov.iov_len -= rc;
read_bytes += rc;
} while (read_bytes != VHOST_USER_HDR_SIZE);
/* qio_channel_readv_full will make socket fds blocking, unblock them */
vmsg_unblock_fds(vmsg);
if (vmsg->size > sizeof(vmsg->payload)) {