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xen/blkback: fix tear-down issues

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Handle tearing down a blkback that hasn't been fully initialized. This
requires carefully checking that fields are allocated before trying to
access them.  Also communication memory is allocated before setting
XBBF_RING_CONNECTED, so gating it's freeing on XBBF_RING_CONNECTED
being set is wrong and will lead to memory leaks.

Also stop using xbb_disconnect() in error paths. Use xenbus_dev_fatal
and let the normal disconnection procedure take care of the cleanup.

Reported by: Ze Dupsys <zedupsys@gmail.com>
Sponsored by: Citrix Systems R&D
This commit is contained in:
Roger Pau Monné 2022-03-27 10:43:42 +02:00
parent f3d54ded28
commit 137381ca60
1 changed files with 30 additions and 33 deletions
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37
sys/dev/xen/blkback/blkback.c
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@ -2774,18 +2774,11 @@ xbb_free_communication_mem(struct xbb_softc *xbb)
static int
xbb_disconnect(struct xbb_softc *xbb)
{
struct gnttab_unmap_grant_ref ops[XBB_MAX_RING_PAGES];
struct gnttab_unmap_grant_ref *op;
u_int ring_idx;
int error;
DPRINTF("\n");
if ((xbb->flags & XBBF_RING_CONNECTED) == 0)
return (0);
mtx_unlock(&xbb->lock);
xen_intr_unbind(&xbb->xen_intr_handle);
if (xbb->io_taskqueue != NULL)
taskqueue_drain(xbb->io_taskqueue, &xbb->io_task);
mtx_lock(&xbb->lock);
@ -2796,6 +2789,12 @@ xbb_disconnect(struct xbb_softc *xbb)
if (xbb->active_request_count != 0)
return (EAGAIN);
if (xbb->flags & XBBF_RING_CONNECTED) {
struct gnttab_unmap_grant_ref ops[XBB_MAX_RING_PAGES];
struct gnttab_unmap_grant_ref *op;
unsigned int ring_idx;
int error;
for (ring_idx = 0, op = ops;
ring_idx < xbb->ring_config.ring_pages;
ring_idx++, op++) {
@ -2810,6 +2809,9 @@ xbb_disconnect(struct xbb_softc *xbb)
if (error != 0)
panic("Grant table op failed (%d)", error);
xbb->flags &= ~XBBF_RING_CONNECTED;
}
xbb_free_communication_mem(xbb);
if (xbb->requests != NULL) {
@ -2839,7 +2841,6 @@ xbb_disconnect(struct xbb_softc *xbb)
xbb->request_lists = NULL;
}
xbb->flags &= ~XBBF_RING_CONNECTED;
return (0);
}
@ -2963,7 +2964,6 @@ xbb_connect_ring(struct xbb_softc *xbb)
INTR_TYPE_BIO | INTR_MPSAFE,
&xbb->xen_intr_handle);
if (error) {
(void)xbb_disconnect(xbb);
xenbus_dev_fatal(xbb->dev, error, "binding event channel");
return (error);
}
@ -3338,6 +3338,13 @@ xbb_connect(struct xbb_softc *xbb)
return;
}
error = xbb_publish_backend_info(xbb);
if (error != 0) {
xenbus_dev_fatal(xbb->dev, error,
"Unable to publish device information");
return;
}
error = xbb_alloc_requests(xbb);
if (error != 0) {
/* Specific errors are reported by xbb_alloc_requests(). */
@ -3359,16 +3366,6 @@ xbb_connect(struct xbb_softc *xbb)
return;
}
if (xbb_publish_backend_info(xbb) != 0) {
/*
* If we can't publish our data, we cannot participate
* in this connection, and waiting for a front-end state
* change will not help the situation.
*/
(void)xbb_disconnect(xbb);
return;
}
/* Ready for I/O. */
xenbus_set_state(xbb->dev, XenbusStateConnected);
}