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authorJens Axboe <axboe@kernel.dk>2019-03-06 19:41:54 +0300
committerJens Axboe <axboe@kernel.dk>2019-03-06 19:41:54 +0300
commite61750c84701310f5a99e1c2e59d77aad5f1da78 (patch)
tree8aeba4edb4e17b7752fa9218e584be46b93f2c97 /drivers/block
parentaaeee62c841cc1e48231e1d60c304d2da9c4e41c (diff)
parent4a8c31a1c6f526ec96a35e613f2a71e26ffbd7dd (diff)
downloadlinux-e61750c84701310f5a99e1c2e59d77aad5f1da78.tar.xz
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
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()
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/xen-blkback/xenbus.c99
1 files changed, 57 insertions, 42 deletions
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index a4bc74e72c39..24896ffb04ed 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -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);
- if (err != 1) {
- err = xenbus_scanf(XBT_NIL, dir, "ring-ref", "%u", &ring_ref[0]);
+ 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/ring-ref", dir);
+ xenbus_dev_fatal(dev, err, "reading %s/%s",
+ dir, ring_ref_name);
return err;
}
- nr_grefs = 1;
- } else {
- unsigned int i;
+ }
- if (ring_page_order > xen_blkif_max_ring_order) {
+ if (err != 1) {
+ 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, "%s/request %d ring page order exceed max:%d",
- dir, ring_page_order,
- xen_blkif_max_ring_order);
+ xenbus_dev_fatal(dev, err, "reading %s/ring-ref", dir);
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;