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>,
"Roger Pau Monné" <roger.pau@citrix.com>
Subject: [PATCH 4.14 24/31] xen/blkfront: dont use gnttab_query_foreign_access() for mapped status
Date: Thu, 10 Mar 2022 15:18:37 +0100 [thread overview]
Message-ID: <20220310140808.245040489@linuxfoundation.org> (raw)
In-Reply-To: <20220310140807.524313448@linuxfoundation.org>
From: Juergen Gross <jgross@suse.com>
Commit abf1fd5919d6238ee3bc5eb4a9b6c3947caa6638 upstream.
It isn't enough to check whether a grant is still being in use by
calling gnttab_query_foreign_access(), as a mapping could be realized
by the other side just after having called that function.
In case the call was done in preparation of revoking a grant it is
better to do so via gnttab_end_foreign_access_ref() and check the
success of that operation instead.
For the ring allocation use alloc_pages_exact() in order to avoid
high order pages in case of a multi-page ring.
If a grant wasn't unmapped by the backend without persistent grants
being used, set the device state to "error".
This is CVE-2022-23036 / part of XSA-396.
Reported-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/block/xen-blkfront.c | 67 +++++++++++++++++++++++++------------------
1 file changed, 39 insertions(+), 28 deletions(-)
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1278,17 +1278,16 @@ static void blkif_free_ring(struct blkfr
list_for_each_entry_safe(persistent_gnt, n,
&rinfo->grants, node) {
list_del(&persistent_gnt->node);
- if (persistent_gnt->gref != GRANT_INVALID_REF) {
- gnttab_end_foreign_access(persistent_gnt->gref,
- 0, 0UL);
- rinfo->persistent_gnts_c--;
- }
+ if (persistent_gnt->gref == GRANT_INVALID_REF ||
+ !gnttab_try_end_foreign_access(persistent_gnt->gref))
+ continue;
+
+ rinfo->persistent_gnts_c--;
if (info->feature_persistent)
__free_page(persistent_gnt->page);
kfree(persistent_gnt);
}
}
- BUG_ON(rinfo->persistent_gnts_c != 0);
for (i = 0; i < BLK_RING_SIZE(info); i++) {
/*
@@ -1345,7 +1344,8 @@ free_shadow:
rinfo->ring_ref[i] = GRANT_INVALID_REF;
}
}
- free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * XEN_PAGE_SIZE));
+ free_pages_exact(rinfo->ring.sring,
+ info->nr_ring_pages * XEN_PAGE_SIZE);
rinfo->ring.sring = NULL;
if (rinfo->irq)
@@ -1429,9 +1429,15 @@ static int blkif_get_final_status(enum b
return BLKIF_RSP_OKAY;
}
-static bool blkif_completion(unsigned long *id,
- struct blkfront_ring_info *rinfo,
- struct blkif_response *bret)
+/*
+ * Return values:
+ * 1 response processed.
+ * 0 missing further responses.
+ * -1 error while processing.
+ */
+static int blkif_completion(unsigned long *id,
+ struct blkfront_ring_info *rinfo,
+ struct blkif_response *bret)
{
int i = 0;
struct scatterlist *sg;
@@ -1505,42 +1511,43 @@ static bool blkif_completion(unsigned lo
}
/* Add the persistent grant into the list of free grants */
for (i = 0; i < num_grant; i++) {
- if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
+ if (!gnttab_try_end_foreign_access(s->grants_used[i]->gref)) {
/*
* If the grant is still mapped by the backend (the
* backend has chosen to make this grant persistent)
* we add it at the head of the list, so it will be
* reused first.
*/
- if (!info->feature_persistent)
- pr_alert_ratelimited("backed has not unmapped grant: %u\n",
- s->grants_used[i]->gref);
+ if (!info->feature_persistent) {
+ pr_alert("backed has not unmapped grant: %u\n",
+ s->grants_used[i]->gref);
+ return -1;
+ }
list_add(&s->grants_used[i]->node, &rinfo->grants);
rinfo->persistent_gnts_c++;
} else {
/*
- * If the grant is not mapped by the backend we end the
- * foreign access and add it to the tail of the list,
- * so it will not be picked again unless we run out of
- * persistent grants.
+ * If the grant is not mapped by the backend we add it
+ * to the tail of the list, so it will not be picked
+ * again unless we run out of persistent grants.
*/
- gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
s->grants_used[i]->gref = GRANT_INVALID_REF;
list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
}
}
if (s->req.operation == BLKIF_OP_INDIRECT) {
for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
- if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
- if (!info->feature_persistent)
- pr_alert_ratelimited("backed has not unmapped grant: %u\n",
- s->indirect_grants[i]->gref);
+ if (!gnttab_try_end_foreign_access(s->indirect_grants[i]->gref)) {
+ if (!info->feature_persistent) {
+ pr_alert("backed has not unmapped grant: %u\n",
+ s->indirect_grants[i]->gref);
+ return -1;
+ }
list_add(&s->indirect_grants[i]->node, &rinfo->grants);
rinfo->persistent_gnts_c++;
} else {
struct page *indirect_page;
- gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
/*
* Add the used indirect page back to the list of
* available pages for indirect grefs.
@@ -1621,12 +1628,17 @@ static irqreturn_t blkif_interrupt(int i
}
if (bret.operation != BLKIF_OP_DISCARD) {
+ int ret;
+
/*
* We may need to wait for an extra response if the
* I/O request is split in 2
*/
- if (!blkif_completion(&id, rinfo, &bret))
+ ret = blkif_completion(&id, rinfo, &bret);
+ if (!ret)
continue;
+ if (unlikely(ret < 0))
+ goto err;
}
if (add_id_to_freelist(rinfo, id)) {
@@ -1732,8 +1744,7 @@ static int setup_blkring(struct xenbus_d
for (i = 0; i < info->nr_ring_pages; i++)
rinfo->ring_ref[i] = GRANT_INVALID_REF;
- sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
- get_order(ring_size));
+ sring = alloc_pages_exact(ring_size, GFP_NOIO);
if (!sring) {
xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
return -ENOMEM;
@@ -1743,7 +1754,7 @@ static int setup_blkring(struct xenbus_d
err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
if (err < 0) {
- free_pages((unsigned long)sring, get_order(ring_size));
+ free_pages_exact(sring, ring_size);
rinfo->ring.sring = NULL;
goto fail;
}
next prev parent reply other threads:[~2022-03-10 14:22 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-10 14:18 [PATCH 4.14 00/31] 4.14.271-rc2 review Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 01/31] x86/speculation: Merge one test in spectre_v2_user_select_mitigation() Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 02/31] x86,bugs: Unconditionally allow spectre_v2=retpoline,amd Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 03/31] x86/speculation: Rename RETPOLINE_AMD to RETPOLINE_LFENCE Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 04/31] x86/speculation: Add eIBRS + Retpoline options Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 05/31] Documentation/hw-vuln: Update spectre doc Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 06/31] x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 07/31] x86/speculation: Use generic retpoline by default on AMD Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 08/31] x86/speculation: Update link to AMD speculation whitepaper Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 09/31] x86/speculation: Warn about Spectre v2 LFENCE mitigation Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 10/31] x86/speculation: Warn about eIBRS + LFENCE + Unprivileged eBPF + SMT Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 11/31] arm/arm64: Provide a wrapper for SMCCC 1.1 calls Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 12/31] arm/arm64: smccc/psci: add arm_smccc_1_1_get_conduit() Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 13/31] ARM: report Spectre v2 status through sysfs Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 14/31] ARM: early traps initialisation Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 15/31] ARM: use LOADADDR() to get load address of sections Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 16/31] ARM: Spectre-BHB workaround Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 17/31] ARM: include unprivileged BPF status in Spectre V2 reporting Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 18/31] ARM: fix build error when BPF_SYSCALL is disabled Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 19/31] ARM: fix co-processor register typo Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 20/31] ARM: Do not use NOCROSSREFS directive with ld.lld Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 21/31] ARM: fix build warning in proc-v7-bugs.c Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 22/31] xen/xenbus: dont let xenbus_grant_ring() remove grants in error case Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 23/31] xen/grant-table: add gnttab_try_end_foreign_access() Greg Kroah-Hartman
2022-03-10 14:18 ` Greg Kroah-Hartman [this message]
2022-03-10 14:18 ` [PATCH 4.14 25/31] xen/netfront: dont use gnttab_query_foreign_access() for mapped status Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 26/31] xen/scsifront: " Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 27/31] xen/gntalloc: dont use gnttab_query_foreign_access() Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 28/31] xen: remove gnttab_query_foreign_access() Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 29/31] xen/9p: use alloc/free_pages_exact() Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 30/31] xen/gnttab: fix gnttab_end_foreign_access() without page specified Greg Kroah-Hartman
2022-03-10 14:18 ` [PATCH 4.14 31/31] xen/netfront: react properly to failing gnttab_end_foreign_access_ref() Greg Kroah-Hartman
2022-03-10 18:48 ` [PATCH 4.14 00/31] 4.14.271-rc2 review Jon Hunter
2022-03-11 1:01 ` Guenter Roeck
2022-03-11 13:18 ` Naresh Kamboju
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