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Merge branch 'stable/for-jens-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen into for-5.1/block-post

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Pull two xen blkback fixes from Konrad.

* 'stable/for-jens-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
  xen/blkback: rework connect_ring() to avoid inconsistent xenstore 'ring-page-order' set by malicious blkfront
  xen/blkback: add stack variable 'blkif' in connect_ring()
This commit is contained in:
Jens Axboe 2019-03-06 09:41:54 -07:00
commit e61750c847
1 changed files with 59 additions and 44 deletions
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103
drivers/block/xen-blkback/xenbus.c
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@ -926,7 +926,7 @@ static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
int err, i, j;
struct xen_blkif *blkif = ring->blkif;
struct xenbus_device *dev = blkif->be->dev;
unsigned int ring_page_order, nr_grefs, evtchn;
unsigned int nr_grefs, evtchn;
err = xenbus_scanf(XBT_NIL, dir, "event-channel", "%u",
&evtchn);
@ -936,43 +936,42 @@ static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
return err;
}
err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-page-order", "%u",
&ring_page_order);
nr_grefs = blkif->nr_ring_pages;
if (unlikely(!nr_grefs)) {
WARN_ON(true);
return -EINVAL;
}
for (i = 0; i < nr_grefs; i++) {
char ring_ref_name[RINGREF_NAME_LEN];
snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
err = xenbus_scanf(XBT_NIL, dir, ring_ref_name,
"%u", &ring_ref[i]);
if (err != 1) {
if (nr_grefs == 1)
break;
err = -EINVAL;
xenbus_dev_fatal(dev, err, "reading %s/%s",
dir, ring_ref_name);
return err;
}
}
if (err != 1) {
err = xenbus_scanf(XBT_NIL, dir, "ring-ref", "%u", &ring_ref[0]);
WARN_ON(nr_grefs != 1);
err = xenbus_scanf(XBT_NIL, dir, "ring-ref", "%u",
&ring_ref[0]);
if (err != 1) {
err = -EINVAL;
xenbus_dev_fatal(dev, err, "reading %s/ring-ref", dir);
return err;
}
nr_grefs = 1;
} else {
unsigned int i;
if (ring_page_order > xen_blkif_max_ring_order) {
err = -EINVAL;
xenbus_dev_fatal(dev, err, "%s/request %d ring page order exceed max:%d",
dir, ring_page_order,
xen_blkif_max_ring_order);
return err;
}
nr_grefs = 1 << ring_page_order;
for (i = 0; i < nr_grefs; i++) {
char ring_ref_name[RINGREF_NAME_LEN];
snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
err = xenbus_scanf(XBT_NIL, dir, ring_ref_name,
"%u", &ring_ref[i]);
if (err != 1) {
err = -EINVAL;
xenbus_dev_fatal(dev, err, "reading %s/%s",
dir, ring_ref_name);
return err;
}
}
}
blkif->nr_ring_pages = nr_grefs;
for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
req = kzalloc(sizeof(*req), GFP_KERNEL);
@ -1023,6 +1022,7 @@ fail:
static int connect_ring(struct backend_info *be)
{
struct xenbus_device *dev = be->dev;
struct xen_blkif *blkif = be->blkif;
unsigned int pers_grants;
char protocol[64] = "";
int err, i;
@ -1030,28 +1030,29 @@ static int connect_ring(struct backend_info *be)
size_t xspathsize;
const size_t xenstore_path_ext_size = 11; /* sufficient for "/queue-NNN" */
unsigned int requested_num_queues = 0;
unsigned int ring_page_order;
pr_debug("%s %s\n", __func__, dev->otherend);
be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
err = xenbus_scanf(XBT_NIL, dev->otherend, "protocol",
"%63s", protocol);
if (err <= 0)
strcpy(protocol, "unspecified, assuming default");
else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
else {
xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
return -ENOSYS;
}
pers_grants = xenbus_read_unsigned(dev->otherend, "feature-persistent",
0);
be->blkif->vbd.feature_gnt_persistent = pers_grants;
be->blkif->vbd.overflow_max_grants = 0;
blkif->vbd.feature_gnt_persistent = pers_grants;
blkif->vbd.overflow_max_grants = 0;
/*
* Read the number of hardware queues from frontend.
@ -1067,16 +1068,30 @@ static int connect_ring(struct backend_info *be)
requested_num_queues, xenblk_max_queues);
return -ENOSYS;
}
be->blkif->nr_rings = requested_num_queues;
if (xen_blkif_alloc_rings(be->blkif))
blkif->nr_rings = requested_num_queues;
if (xen_blkif_alloc_rings(blkif))
return -ENOMEM;
pr_info("%s: using %d queues, protocol %d (%s) %s\n", dev->nodename,
be->blkif->nr_rings, be->blkif->blk_protocol, protocol,
blkif->nr_rings, blkif->blk_protocol, protocol,
pers_grants ? "persistent grants" : "");
if (be->blkif->nr_rings == 1)
return read_per_ring_refs(&be->blkif->rings[0], dev->otherend);
ring_page_order = xenbus_read_unsigned(dev->otherend,
"ring-page-order", 0);
if (ring_page_order > xen_blkif_max_ring_order) {
err = -EINVAL;
xenbus_dev_fatal(dev, err,
"requested ring page order %d exceed max:%d",
ring_page_order,
xen_blkif_max_ring_order);
return err;
}
blkif->nr_ring_pages = 1 << ring_page_order;
if (blkif->nr_rings == 1)
return read_per_ring_refs(&blkif->rings[0], dev->otherend);
else {
xspathsize = strlen(dev->otherend) + xenstore_path_ext_size;
xspath = kmalloc(xspathsize, GFP_KERNEL);
@ -1085,10 +1100,10 @@ static int connect_ring(struct backend_info *be)
return -ENOMEM;
}
for (i = 0; i < be->blkif->nr_rings; i++) {
for (i = 0; i < blkif->nr_rings; i++) {
memset(xspath, 0, xspathsize);
snprintf(xspath, xspathsize, "%s/queue-%u", dev->otherend, i);
err = read_per_ring_refs(&be->blkif->rings[i], xspath);
err = read_per_ring_refs(&blkif->rings[i], xspath);
if (err) {
kfree(xspath);
return err;