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linux/virt/kvm/irqchip.c
Paolo Bonzini c622a3c21e KVM: irqfd: fix NULL pointer dereference in kvm_irq_map_gsi
Found by syzkaller:

    BUG: unable to handle kernel NULL pointer dereference at 0000000000000120
    IP: [<ffffffffa0797202>] kvm_irq_map_gsi+0x12/0x90 [kvm]
    PGD 6f80b067 PUD b6535067 PMD 0
    Oops: 0000 [] SMP
    CPU: 3 PID: 4988 Comm: a.out Not tainted 4.4.9-300.fc23.x86_64 
    [...]
    Call Trace:
     [<ffffffffa0795f62>] irqfd_update+0x32/0xc0 [kvm]
     [<ffffffffa0796c7c>] kvm_irqfd+0x3dc/0x5b0 [kvm]
     [<ffffffffa07943f4>] kvm_vm_ioctl+0x164/0x6f0 [kvm]
     [<ffffffff81241648>] do_vfs_ioctl+0x298/0x480
     [<ffffffff812418a9>] SyS_ioctl+0x79/0x90
     [<ffffffff817a1062>] tracesys_phase2+0x84/0x89
    Code: b5 71 a7 e0 5b 41 5c 41 5d 5d f3 c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 8b 8f 10 2e 00 00 31 c0 48 89 e5 <39> 91 20 01 00 00 76 6a 48 63 d2 48 8b 94 d1 28 01 00 00 48 85
    RIP  [<ffffffffa0797202>] kvm_irq_map_gsi+0x12/0x90 [kvm]
     RSP <ffff8800926cbca8>
    CR2: 0000000000000120

Testcase:

    #include <unistd.h>
    #include <sys/syscall.h>
    #include <string.h>
    #include <stdint.h>
    #include <linux/kvm.h>
    #include <fcntl.h>
    #include <sys/ioctl.h>

    long r[26];

    int main()
    {
        memset(r, -1, sizeof(r));
        r[2] = open("/dev/kvm", 0);
        r[3] = ioctl(r[2], KVM_CREATE_VM, 0);

        struct kvm_irqfd ifd;
        ifd.fd = syscall(SYS_eventfd2, 5, 0);
        ifd.gsi = 3;
        ifd.flags = 2;
        ifd.resamplefd = ifd.fd;
        r[25] = ioctl(r[3], KVM_IRQFD, &ifd);
        return 0;
    }

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2016-06-02 17:38:50 +02:00

241 lines
5.8 KiB
C

/*
* irqchip.c: Common API for in kernel interrupt controllers
* Copyright (c) 2007, Intel Corporation.
* Copyright 2010 Red Hat, Inc. and/or its affiliates.
* Copyright (c) 2013, Alexander Graf <agraf@suse.de>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 59 Temple
* Place - Suite 330, Boston, MA 02111-1307 USA.
*
* This file is derived from virt/kvm/irq_comm.c.
*
* Authors:
* Yaozu (Eddie) Dong <Eddie.dong@intel.com>
* Alexander Graf <agraf@suse.de>
*/
#include <linux/kvm_host.h>
#include <linux/slab.h>
#include <linux/srcu.h>
#include <linux/export.h>
#include <trace/events/kvm.h>
#include "irq.h"
int kvm_irq_map_gsi(struct kvm *kvm,
struct kvm_kernel_irq_routing_entry *entries, int gsi)
{
struct kvm_irq_routing_table *irq_rt;
struct kvm_kernel_irq_routing_entry *e;
int n = 0;
irq_rt = srcu_dereference_check(kvm->irq_routing, &kvm->irq_srcu,
lockdep_is_held(&kvm->irq_lock));
if (irq_rt && gsi < irq_rt->nr_rt_entries) {
hlist_for_each_entry(e, &irq_rt->map[gsi], link) {
entries[n] = *e;
++n;
}
}
return n;
}
int kvm_irq_map_chip_pin(struct kvm *kvm, unsigned irqchip, unsigned pin)
{
struct kvm_irq_routing_table *irq_rt;
irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);
return irq_rt->chip[irqchip][pin];
}
int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi)
{
struct kvm_kernel_irq_routing_entry route;
if (!irqchip_in_kernel(kvm) || msi->flags != 0)
return -EINVAL;
route.msi.address_lo = msi->address_lo;
route.msi.address_hi = msi->address_hi;
route.msi.data = msi->data;
return kvm_set_msi(&route, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1, false);
}
/*
* Return value:
* < 0 Interrupt was ignored (masked or not delivered for other reasons)
* = 0 Interrupt was coalesced (previous irq is still pending)
* > 0 Number of CPUs interrupt was delivered to
*/
int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level,
bool line_status)
{
struct kvm_kernel_irq_routing_entry irq_set[KVM_NR_IRQCHIPS];
int ret = -1, i, idx;
trace_kvm_set_irq(irq, level, irq_source_id);
/* Not possible to detect if the guest uses the PIC or the
* IOAPIC. So set the bit in both. The guest will ignore
* writes to the unused one.
*/
idx = srcu_read_lock(&kvm->irq_srcu);
i = kvm_irq_map_gsi(kvm, irq_set, irq);
srcu_read_unlock(&kvm->irq_srcu, idx);
while (i--) {
int r;
r = irq_set[i].set(&irq_set[i], kvm, irq_source_id, level,
line_status);
if (r < 0)
continue;
ret = r + ((ret < 0) ? 0 : ret);
}
return ret;
}
static void free_irq_routing_table(struct kvm_irq_routing_table *rt)
{
int i;
if (!rt)
return;
for (i = 0; i < rt->nr_rt_entries; ++i) {
struct kvm_kernel_irq_routing_entry *e;
struct hlist_node *n;
hlist_for_each_entry_safe(e, n, &rt->map[i], link) {
hlist_del(&e->link);
kfree(e);
}
}
kfree(rt);
}
void kvm_free_irq_routing(struct kvm *kvm)
{
/* Called only during vm destruction. Nobody can use the pointer
at this stage */
struct kvm_irq_routing_table *rt = rcu_access_pointer(kvm->irq_routing);
free_irq_routing_table(rt);
}
static int setup_routing_entry(struct kvm_irq_routing_table *rt,
struct kvm_kernel_irq_routing_entry *e,
const struct kvm_irq_routing_entry *ue)
{
int r = -EINVAL;
struct kvm_kernel_irq_routing_entry *ei;
/*
* Do not allow GSI to be mapped to the same irqchip more than once.
* Allow only one to one mapping between GSI and non-irqchip routing.
*/
hlist_for_each_entry(ei, &rt->map[ue->gsi], link)
if (ei->type != KVM_IRQ_ROUTING_IRQCHIP ||
ue->type != KVM_IRQ_ROUTING_IRQCHIP ||
ue->u.irqchip.irqchip == ei->irqchip.irqchip)
return r;
e->gsi = ue->gsi;
e->type = ue->type;
r = kvm_set_routing_entry(e, ue);
if (r)
goto out;
if (e->type == KVM_IRQ_ROUTING_IRQCHIP)
rt->chip[e->irqchip.irqchip][e->irqchip.pin] = e->gsi;
hlist_add_head(&e->link, &rt->map[e->gsi]);
r = 0;
out:
return r;
}
void __attribute__((weak)) kvm_arch_irq_routing_update(struct kvm *kvm)
{
}
int kvm_set_irq_routing(struct kvm *kvm,
const struct kvm_irq_routing_entry *ue,
unsigned nr,
unsigned flags)
{
struct kvm_irq_routing_table *new, *old;
u32 i, j, nr_rt_entries = 0;
int r;
for (i = 0; i < nr; ++i) {
if (ue[i].gsi >= KVM_MAX_IRQ_ROUTES)
return -EINVAL;
nr_rt_entries = max(nr_rt_entries, ue[i].gsi);
}
nr_rt_entries += 1;
new = kzalloc(sizeof(*new) + (nr_rt_entries * sizeof(struct hlist_head)),
GFP_KERNEL);
if (!new)
return -ENOMEM;
new->nr_rt_entries = nr_rt_entries;
for (i = 0; i < KVM_NR_IRQCHIPS; i++)
for (j = 0; j < KVM_IRQCHIP_NUM_PINS; j++)
new->chip[i][j] = -1;
for (i = 0; i < nr; ++i) {
struct kvm_kernel_irq_routing_entry *e;
r = -ENOMEM;
e = kzalloc(sizeof(*e), GFP_KERNEL);
if (!e)
goto out;
r = -EINVAL;
if (ue->flags) {
kfree(e);
goto out;
}
r = setup_routing_entry(new, e, ue);
if (r) {
kfree(e);
goto out;
}
++ue;
}
mutex_lock(&kvm->irq_lock);
old = kvm->irq_routing;
rcu_assign_pointer(kvm->irq_routing, new);
kvm_irq_routing_update(kvm);
kvm_arch_irq_routing_update(kvm);
mutex_unlock(&kvm->irq_lock);
kvm_arch_post_irq_routing_update(kvm);
synchronize_srcu_expedited(&kvm->irq_srcu);
new = old;
r = 0;
out:
free_irq_routing_table(new);
return r;
}