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-rw-r--r--system/xen/xsa/xsa221.patch194
1 files changed, 194 insertions, 0 deletions
diff --git a/system/xen/xsa/xsa221.patch b/system/xen/xsa/xsa221.patch
new file mode 100644
index 0000000000000..c7fec966683ff
--- /dev/null
+++ b/system/xen/xsa/xsa221.patch
@@ -0,0 +1,194 @@
+From: Jan Beulich <jbeulich@suse.com>
+Subject: evtchn: avoid NULL derefs
+
+Commit fbbd5009e6 ("evtchn: refactor low-level event channel port ops")
+added a de-reference of the struct evtchn pointer for a port without
+first making sure the bucket pointer is non-NULL. This de-reference is
+actually entirely unnecessary, as all relevant callers (beyond the
+problematic do_poll()) already hold the port number in their hands, and
+the actual leaf functions need nothing else.
+
+For FIFO event channels there's a second problem in that the ordering
+of reads and updates to ->num_evtchns and ->event_array[] was so far
+undefined (the read side isn't always holding the domain's event lock).
+Add respective barriers.
+
+This is XSA-221.
+
+Reported-by: Ankur Arora <ankur.a.arora@oracle.com>
+Signed-off-by: Jan Beulich <jbeulich@suse.com>
+
+--- a/xen/arch/x86/irq.c
++++ b/xen/arch/x86/irq.c
+@@ -1486,7 +1486,7 @@ int pirq_guest_unmask(struct domain *d)
+ {
+ pirq = pirqs[i]->pirq;
+ if ( pirqs[i]->masked &&
+- !evtchn_port_is_masked(d, evtchn_from_port(d, pirqs[i]->evtchn)) )
++ !evtchn_port_is_masked(d, pirqs[i]->evtchn) )
+ pirq_guest_eoi(pirqs[i]);
+ }
+ } while ( ++pirq < d->nr_pirqs && n == ARRAY_SIZE(pirqs) );
+@@ -2244,7 +2244,6 @@ static void dump_irqs(unsigned char key)
+ int i, irq, pirq;
+ struct irq_desc *desc;
+ irq_guest_action_t *action;
+- struct evtchn *evtchn;
+ struct domain *d;
+ const struct pirq *info;
+ unsigned long flags;
+@@ -2287,11 +2286,10 @@ static void dump_irqs(unsigned char key)
+ d = action->guest[i];
+ pirq = domain_irq_to_pirq(d, irq);
+ info = pirq_info(d, pirq);
+- evtchn = evtchn_from_port(d, info->evtchn);
+ printk("%u:%3d(%c%c%c)",
+ d->domain_id, pirq,
+- (evtchn_port_is_pending(d, evtchn) ? 'P' : '-'),
+- (evtchn_port_is_masked(d, evtchn) ? 'M' : '-'),
++ evtchn_port_is_pending(d, info->evtchn) ? 'P' : '-',
++ evtchn_port_is_masked(d, info->evtchn) ? 'M' : '-',
+ (info->masked ? 'M' : '-'));
+ if ( i != action->nr_guests )
+ printk(",");
+--- a/xen/common/event_2l.c
++++ b/xen/common/event_2l.c
+@@ -61,16 +61,20 @@ static void evtchn_2l_unmask(struct doma
+ }
+ }
+
+-static bool_t evtchn_2l_is_pending(struct domain *d,
+- const struct evtchn *evtchn)
++static bool_t evtchn_2l_is_pending(struct domain *d, evtchn_port_t port)
+ {
+- return test_bit(evtchn->port, &shared_info(d, evtchn_pending));
++ unsigned int max_ports = BITS_PER_EVTCHN_WORD(d) * BITS_PER_EVTCHN_WORD(d);
++
++ ASSERT(port < max_ports);
++ return port < max_ports && test_bit(port, &shared_info(d, evtchn_pending));
+ }
+
+-static bool_t evtchn_2l_is_masked(struct domain *d,
+- const struct evtchn *evtchn)
++static bool_t evtchn_2l_is_masked(struct domain *d, evtchn_port_t port)
+ {
+- return test_bit(evtchn->port, &shared_info(d, evtchn_mask));
++ unsigned int max_ports = BITS_PER_EVTCHN_WORD(d) * BITS_PER_EVTCHN_WORD(d);
++
++ ASSERT(port < max_ports);
++ return port >= max_ports || test_bit(port, &shared_info(d, evtchn_mask));
+ }
+
+ static void evtchn_2l_print_state(struct domain *d,
+--- a/xen/common/event_channel.c
++++ b/xen/common/event_channel.c
+@@ -1380,8 +1380,8 @@ static void domain_dump_evtchn_info(stru
+
+ printk(" %4u [%d/%d/",
+ port,
+- !!evtchn_port_is_pending(d, chn),
+- !!evtchn_port_is_masked(d, chn));
++ evtchn_port_is_pending(d, port),
++ evtchn_port_is_masked(d, port));
+ evtchn_port_print_state(d, chn);
+ printk("]: s=%d n=%d x=%d",
+ chn->state, chn->notify_vcpu_id, chn->xen_consumer);
+--- a/xen/common/event_fifo.c
++++ b/xen/common/event_fifo.c
+@@ -27,6 +27,12 @@ static inline event_word_t *evtchn_fifo_
+ if ( unlikely(port >= d->evtchn_fifo->num_evtchns) )
+ return NULL;
+
++ /*
++ * Callers aren't required to hold d->event_lock, so we need to synchronize
++ * with add_page_to_event_array().
++ */
++ smp_rmb();
++
+ p = port / EVTCHN_FIFO_EVENT_WORDS_PER_PAGE;
+ w = port % EVTCHN_FIFO_EVENT_WORDS_PER_PAGE;
+
+@@ -287,24 +293,22 @@ static void evtchn_fifo_unmask(struct do
+ evtchn_fifo_set_pending(v, evtchn);
+ }
+
+-static bool_t evtchn_fifo_is_pending(struct domain *d,
+- const struct evtchn *evtchn)
++static bool_t evtchn_fifo_is_pending(struct domain *d, evtchn_port_t port)
+ {
+ event_word_t *word;
+
+- word = evtchn_fifo_word_from_port(d, evtchn->port);
++ word = evtchn_fifo_word_from_port(d, port);
+ if ( unlikely(!word) )
+ return 0;
+
+ return test_bit(EVTCHN_FIFO_PENDING, word);
+ }
+
+-static bool_t evtchn_fifo_is_masked(struct domain *d,
+- const struct evtchn *evtchn)
++static bool_t evtchn_fifo_is_masked(struct domain *d, evtchn_port_t port)
+ {
+ event_word_t *word;
+
+- word = evtchn_fifo_word_from_port(d, evtchn->port);
++ word = evtchn_fifo_word_from_port(d, port);
+ if ( unlikely(!word) )
+ return 1;
+
+@@ -593,6 +597,10 @@ static int add_page_to_event_array(struc
+ return rc;
+
+ d->evtchn_fifo->event_array[slot] = virt;
++
++ /* Synchronize with evtchn_fifo_word_from_port(). */
++ smp_wmb();
++
+ d->evtchn_fifo->num_evtchns += EVTCHN_FIFO_EVENT_WORDS_PER_PAGE;
+
+ /*
+--- a/xen/common/schedule.c
++++ b/xen/common/schedule.c
+@@ -965,7 +965,7 @@ static long do_poll(struct sched_poll *s
+ goto out;
+
+ rc = 0;
+- if ( evtchn_port_is_pending(d, evtchn_from_port(d, port)) )
++ if ( evtchn_port_is_pending(d, port) )
+ goto out;
+ }
+
+--- a/xen/include/xen/event.h
++++ b/xen/include/xen/event.h
+@@ -137,8 +137,8 @@ struct evtchn_port_ops {
+ void (*set_pending)(struct vcpu *v, struct evtchn *evtchn);
+ void (*clear_pending)(struct domain *d, struct evtchn *evtchn);
+ void (*unmask)(struct domain *d, struct evtchn *evtchn);
+- bool_t (*is_pending)(struct domain *d, const struct evtchn *evtchn);
+- bool_t (*is_masked)(struct domain *d, const struct evtchn *evtchn);
++ bool_t (*is_pending)(struct domain *d, evtchn_port_t port);
++ bool_t (*is_masked)(struct domain *d, evtchn_port_t port);
+ /*
+ * Is the port unavailable because it's still being cleaned up
+ * after being closed?
+@@ -175,15 +175,15 @@ static inline void evtchn_port_unmask(st
+ }
+
+ static inline bool_t evtchn_port_is_pending(struct domain *d,
+- const struct evtchn *evtchn)
++ evtchn_port_t port)
+ {
+- return d->evtchn_port_ops->is_pending(d, evtchn);
++ return d->evtchn_port_ops->is_pending(d, port);
+ }
+
+ static inline bool_t evtchn_port_is_masked(struct domain *d,
+- const struct evtchn *evtchn)
++ evtchn_port_t port)
+ {
+- return d->evtchn_port_ops->is_masked(d, evtchn);
++ return d->evtchn_port_ops->is_masked(d, port);
+ }
+
+ static inline bool_t evtchn_port_is_busy(struct domain *d, evtchn_port_t port)
generated by cgit v1.2.3 (git 2.26.2) at 2024-12-20 11:54:28 +0000