From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org,
Demi Marie Obenour <demi@invisiblethingslab.com>,
Juergen Gross <jgross@suse.com>, Jan Beulich <jbeulich@suse.com>
Subject: [PATCH 4.19 33/33] xen/netfront: react properly to failing gnttab_end_foreign_access_ref()
Date: Thu, 10 Mar 2022 15:19:00 +0100 [thread overview]
Message-ID: <20220310140808.718555574@linuxfoundation.org> (raw)
In-Reply-To: <20220310140807.749164737@linuxfoundation.org>
From: Juergen Gross <jgross@suse.com>
Commit 66e3531b33ee51dad17c463b4d9c9f52e341503d upstream.
When calling gnttab_end_foreign_access_ref() the returned value must
be tested and the reaction to that value should be appropriate.
In case of failure in xennet_get_responses() the reaction should not be
to crash the system, but to disable the network device.
The calls in setup_netfront() can be replaced by calls of
gnttab_end_foreign_access(). While at it avoid double free of ring
pages and grant references via xennet_disconnect_backend() in this case.
This is CVE-2022-23042 / part of XSA-396.
Reported-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/xen-netfront.c | 48 +++++++++++++++++++++++++++++----------------
1 file changed, 31 insertions(+), 17 deletions(-)
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -862,7 +862,6 @@ static int xennet_get_responses(struct n
int max = XEN_NETIF_NR_SLOTS_MIN + (rx->status <= RX_COPY_THRESHOLD);
int slots = 1;
int err = 0;
- unsigned long ret;
if (rx->flags & XEN_NETRXF_extra_info) {
err = xennet_get_extras(queue, extras, rp);
@@ -893,8 +892,13 @@ static int xennet_get_responses(struct n
goto next;
}
- ret = gnttab_end_foreign_access_ref(ref, 0);
- BUG_ON(!ret);
+ if (!gnttab_end_foreign_access_ref(ref, 0)) {
+ dev_alert(dev,
+ "Grant still in use by backend domain\n");
+ queue->info->broken = true;
+ dev_alert(dev, "Disabled for further use\n");
+ return -EINVAL;
+ }
gnttab_release_grant_reference(&queue->gref_rx_head, ref);
@@ -1098,6 +1102,10 @@ static int xennet_poll(struct napi_struc
err = xennet_get_responses(queue, &rinfo, rp, &tmpq);
if (unlikely(err)) {
+ if (queue->info->broken) {
+ spin_unlock(&queue->rx_lock);
+ return 0;
+ }
err:
while ((skb = __skb_dequeue(&tmpq)))
__skb_queue_tail(&errq, skb);
@@ -1676,7 +1684,7 @@ static int setup_netfront(struct xenbus_
struct netfront_queue *queue, unsigned int feature_split_evtchn)
{
struct xen_netif_tx_sring *txs;
- struct xen_netif_rx_sring *rxs;
+ struct xen_netif_rx_sring *rxs = NULL;
grant_ref_t gref;
int err;
@@ -1696,21 +1704,21 @@ static int setup_netfront(struct xenbus_
err = xenbus_grant_ring(dev, txs, 1, &gref);
if (err < 0)
- goto grant_tx_ring_fail;
+ goto fail;
queue->tx_ring_ref = gref;
rxs = (struct xen_netif_rx_sring *)get_zeroed_page(GFP_NOIO | __GFP_HIGH);
if (!rxs) {
err = -ENOMEM;
xenbus_dev_fatal(dev, err, "allocating rx ring page");
- goto alloc_rx_ring_fail;
+ goto fail;
}
SHARED_RING_INIT(rxs);
FRONT_RING_INIT(&queue->rx, rxs, XEN_PAGE_SIZE);
err = xenbus_grant_ring(dev, rxs, 1, &gref);
if (err < 0)
- goto grant_rx_ring_fail;
+ goto fail;
queue->rx_ring_ref = gref;
if (feature_split_evtchn)
@@ -1723,22 +1731,28 @@ static int setup_netfront(struct xenbus_
err = setup_netfront_single(queue);
if (err)
- goto alloc_evtchn_fail;
+ goto fail;
return 0;
/* If we fail to setup netfront, it is safe to just revoke access to
* granted pages because backend is not accessing it at this point.
*/
-alloc_evtchn_fail:
- gnttab_end_foreign_access_ref(queue->rx_ring_ref, 0);
-grant_rx_ring_fail:
- free_page((unsigned long)rxs);
-alloc_rx_ring_fail:
- gnttab_end_foreign_access_ref(queue->tx_ring_ref, 0);
-grant_tx_ring_fail:
- free_page((unsigned long)txs);
-fail:
+ fail:
+ if (queue->rx_ring_ref != GRANT_INVALID_REF) {
+ gnttab_end_foreign_access(queue->rx_ring_ref, 0,
+ (unsigned long)rxs);
+ queue->rx_ring_ref = GRANT_INVALID_REF;
+ } else {
+ free_page((unsigned long)rxs);
+ }
+ if (queue->tx_ring_ref != GRANT_INVALID_REF) {
+ gnttab_end_foreign_access(queue->tx_ring_ref, 0,
+ (unsigned long)txs);
+ queue->tx_ring_ref = GRANT_INVALID_REF;
+ } else {
+ free_page((unsigned long)txs);
+ }
return err;
}
next prev parent reply other threads:[~2022-03-10 14:33 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-10 14:18 [PATCH 4.19 00/33] 4.19.234-rc2 review Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 01/33] x86/speculation: Merge one test in spectre_v2_user_select_mitigation() Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 02/33] x86,bugs: Unconditionally allow spectre_v2=retpoline,amd Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 03/33] x86/speculation: Rename RETPOLINE_AMD to RETPOLINE_LFENCE Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 04/33] x86/speculation: Add eIBRS + Retpoline options Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 05/33] Documentation/hw-vuln: Update spectre doc Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 06/33] x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 07/33] x86/speculation: Use generic retpoline by default on AMD Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 08/33] x86/speculation: Update link to AMD speculation whitepaper Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 09/33] x86/speculation: Warn about Spectre v2 LFENCE mitigation Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 10/33] x86/speculation: Warn about eIBRS + LFENCE + Unprivileged eBPF + SMT Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 11/33] arm/arm64: Provide a wrapper for SMCCC 1.1 calls Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 12/33] arm/arm64: smccc/psci: add arm_smccc_1_1_get_conduit() Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 13/33] ARM: report Spectre v2 status through sysfs Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 14/33] ARM: early traps initialisation Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 15/33] ARM: use LOADADDR() to get load address of sections Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 16/33] ARM: Spectre-BHB workaround Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 17/33] ARM: include unprivileged BPF status in Spectre V2 reporting Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 18/33] ARM: fix build error when BPF_SYSCALL is disabled Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 19/33] kbuild: add CONFIG_LD_IS_LLD Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 20/33] ARM: fix co-processor register typo Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 21/33] ARM: Do not use NOCROSSREFS directive with ld.lld Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 22/33] ARM: fix build warning in proc-v7-bugs.c Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 23/33] xen/xenbus: dont let xenbus_grant_ring() remove grants in error case Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 24/33] xen/grant-table: add gnttab_try_end_foreign_access() Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 25/33] xen/blkfront: dont use gnttab_query_foreign_access() for mapped status Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 26/33] xen/netfront: " Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 27/33] xen/scsifront: " Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 28/33] xen/gntalloc: dont use gnttab_query_foreign_access() Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 29/33] xen: remove gnttab_query_foreign_access() Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 30/33] xen/9p: use alloc/free_pages_exact() Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 31/33] xen/pvcalls: " Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.19 32/33] xen/gnttab: fix gnttab_end_foreign_access() without page specified Greg Kroah-Hartman
2022-03-10 14:19 ` Greg Kroah-Hartman [this message]
2022-03-10 18:00 ` [PATCH 4.19 00/33] 4.19.234-rc2 review Pavel Machek
2022-03-10 18:48 ` Jon Hunter
2022-03-10 19:34 ` Shuah Khan
2022-03-11 1:01 ` Guenter Roeck
2022-03-11 10:09 ` Sudip Mukherjee
2022-03-11 12:32 ` Naresh Kamboju
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