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authorJason Wang <jasowang@redhat.com>2015-09-15 14:41:56 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-10-22 14:43:10 -0700
commitc286128ffc7ffaeaf5cf8d7b0b64c9883160a636 (patch)
tree65cce2ce4049d94ffbc97e4caac358f157b7adc0 /virt
parent348a20a23f03953f1a0ab57b55cd9079084b14f4 (diff)
downloadlinux-linaro-stable-c286128ffc7ffaeaf5cf8d7b0b64c9883160a636.tar.gz
kvm: fix double free for fast mmio eventfd
commit eefd6b06b17c5478e7c24bea6f64beaa2c431ca6 upstream. We register wildcard mmio eventfd on two buses, once for KVM_MMIO_BUS and once on KVM_FAST_MMIO_BUS but with a single iodev instance. This will lead to an issue: kvm_io_bus_destroy() knows nothing about the devices on two buses pointing to a single dev. Which will lead to double free[1] during exit. Fix this by allocating two instances of iodevs then registering one on KVM_MMIO_BUS and another on KVM_FAST_MMIO_BUS. CPU: 1 PID: 2894 Comm: qemu-system-x86 Not tainted 3.19.0-26-generic #28-Ubuntu Hardware name: LENOVO 2356BG6/2356BG6, BIOS G7ET96WW (2.56 ) 09/12/2013 task: ffff88009ae0c4b0 ti: ffff88020e7f0000 task.ti: ffff88020e7f0000 RIP: 0010:[<ffffffffc07e25d8>] [<ffffffffc07e25d8>] ioeventfd_release+0x28/0x60 [kvm] RSP: 0018:ffff88020e7f3bc8 EFLAGS: 00010292 RAX: dead000000200200 RBX: ffff8801ec19c900 RCX: 000000018200016d RDX: ffff8801ec19cf80 RSI: ffffea0008bf1d40 RDI: ffff8801ec19c900 RBP: ffff88020e7f3bd8 R08: 000000002fc75a01 R09: 000000018200016d R10: ffffffffc07df6ae R11: ffff88022fc75a98 R12: ffff88021e7cc000 R13: ffff88021e7cca48 R14: ffff88021e7cca50 R15: ffff8801ec19c880 FS: 00007fc1ee3e6700(0000) GS:ffff88023e240000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8f389d8000 CR3: 000000023dc13000 CR4: 00000000001427e0 Stack: ffff88021e7cc000 0000000000000000 ffff88020e7f3be8 ffffffffc07e2622 ffff88020e7f3c38 ffffffffc07df69a ffff880232524160 ffff88020e792d80 0000000000000000 ffff880219b78c00 0000000000000008 ffff8802321686a8 Call Trace: [<ffffffffc07e2622>] ioeventfd_destructor+0x12/0x20 [kvm] [<ffffffffc07df69a>] kvm_put_kvm+0xca/0x210 [kvm] [<ffffffffc07df818>] kvm_vcpu_release+0x18/0x20 [kvm] [<ffffffff811f69f7>] __fput+0xe7/0x250 [<ffffffff811f6bae>] ____fput+0xe/0x10 [<ffffffff81093f04>] task_work_run+0xd4/0xf0 [<ffffffff81079358>] do_exit+0x368/0xa50 [<ffffffff81082c8f>] ? recalc_sigpending+0x1f/0x60 [<ffffffff81079ad5>] do_group_exit+0x45/0xb0 [<ffffffff81085c71>] get_signal+0x291/0x750 [<ffffffff810144d8>] do_signal+0x28/0xab0 [<ffffffff810f3a3b>] ? do_futex+0xdb/0x5d0 [<ffffffff810b7028>] ? __wake_up_locked_key+0x18/0x20 [<ffffffff810f3fa6>] ? SyS_futex+0x76/0x170 [<ffffffff81014fc9>] do_notify_resume+0x69/0xb0 [<ffffffff817cb9af>] int_signal+0x12/0x17 Code: 5d c3 90 0f 1f 44 00 00 55 48 89 e5 53 48 89 fb 48 83 ec 08 48 8b 7f 20 e8 06 d6 a5 c0 48 8b 43 08 48 8b 13 48 89 df 48 89 42 08 <48> 89 10 48 b8 00 01 10 00 00 RIP [<ffffffffc07e25d8>] ioeventfd_release+0x28/0x60 [kvm] RSP <ffff88020e7f3bc8> Cc: Gleb Natapov <gleb@kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/eventfd.c43
1 files changed, 25 insertions, 18 deletions
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 0829c7f197a0..79db45336e3a 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -817,16 +817,6 @@ static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
if (ret < 0)
goto unlock_fail;
- /* When length is ignored, MMIO is also put on a separate bus, for
- * faster lookups.
- */
- if (!args->len && bus_idx == KVM_MMIO_BUS) {
- ret = kvm_io_bus_register_dev(kvm, KVM_FAST_MMIO_BUS,
- p->addr, 0, &p->dev);
- if (ret < 0)
- goto register_fail;
- }
-
kvm->buses[bus_idx]->ioeventfd_count++;
list_add_tail(&p->list, &kvm->ioeventfds);
@@ -834,8 +824,6 @@ static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
return 0;
-register_fail:
- kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
unlock_fail:
mutex_unlock(&kvm->slots_lock);
@@ -874,10 +862,6 @@ kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
continue;
kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
- if (!p->length && p->bus_idx == KVM_MMIO_BUS) {
- kvm_io_bus_unregister_dev(kvm, KVM_FAST_MMIO_BUS,
- &p->dev);
- }
kvm->buses[bus_idx]->ioeventfd_count--;
ioeventfd_release(p);
ret = 0;
@@ -894,14 +878,19 @@ kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
{
enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
+ int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
+
+ if (!args->len && bus_idx == KVM_MMIO_BUS)
+ kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
- return kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
+ return ret;
}
static int
kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
{
enum kvm_bus bus_idx;
+ int ret;
bus_idx = ioeventfd_bus_from_flags(args->flags);
/* must be natural-word sized, or 0 to ignore length */
@@ -930,7 +919,25 @@ kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
KVM_IOEVENTFD_FLAG_DATAMATCH))
return -EINVAL;
- return kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
+ ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
+ if (ret)
+ goto fail;
+
+ /* When length is ignored, MMIO is also put on a separate bus, for
+ * faster lookups.
+ */
+ if (!args->len && bus_idx == KVM_MMIO_BUS) {
+ ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
+ if (ret < 0)
+ goto fast_fail;
+ }
+
+ return 0;
+
+fast_fail:
+ kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
+fail:
+ return ret;
}
int