[PATCH 4.0 010/148] kvm: fix crash in kvm_vcpu_reload_apic_access_page

Greg Kroah-Hartman
2015-06-03T12:17:09Z

From: Andrea Arcangeli <aarcange@redhat.com>

commit e8fd5e9e9984675f45b9a5485909c143fbde248f upstream.

memslot->userfault_addr is set by the kernel with a mmap executed
from the kernel but the userland can still munmap it and lead to the
below oops after memslot->userfault_addr points to a host virtual
address that has no vma or mapping.

[ 327.538306] BUG: unable to handle kernel paging request at fffffffffffffffe
[ 327.538407] IP: [<ffffffff811a7b55>] put_page+0x5/0x50
[ 327.538474] PGD 1a01067 PUD 1a03067 PMD 0
[ 327.538529] Oops: 0000 [#1] SMP
[ 327.538574] Modules linked in: macvtap macvlan xt_CHECKSUM iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT iptable_filter ip_tables tun bridge stp llc rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache xprtrdma ib_isert iscsi_target_mod ib_iser libiscsi scsi_transport_iscsi ib_srpt target_core_mod ib_srp scsi_transport_srp scsi_tgt ib_ipoib rdma_ucm ib_ucm ib_uverbs ib_umad rdma_cm ib_cm iw_cm ipmi_devintf iTCO_wdt iTCO_vendor_support intel_powerclamp coretemp dcdbas intel_rapl kvm_intel kvm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel lrw gf128mul glue_helper ablk_helper cryptd pcspkr sb_edac edac_core ipmi_si ipmi_msghandler acpi_pad wmi acpi_power_meter lpc_ich mfd_core mei_me
[ 327.539488] mei shpchp nfsd auth_rpcgss nfs_acl lockd grace sunrpc mlx4_ib ib_sa ib_mad ib_core mlx4_en vxlan ib_addr ip_tunnel xfs libcrc32c sd_mod crc_t10dif crct10dif_common crc32c_intel mgag200 syscopyarea sysfillrect sysimgblt i2c_algo_bit drm_kms_helper ttm drm ahci i2c_core libahci mlx4_core libata tg3 ptp pps_core megaraid_sas ntb dm_mirror dm_region_hash dm_log dm_mod
[ 327.539956] CPU: 3 PID: 3161 Comm: qemu-kvm Not tainted 3.10.0-240.el7.userfault19.4ca4011.x86_64.debug #1
[ 327.540045] Hardware name: Dell Inc. PowerEdge R420/0CN7CM, BIOS 2.1.2 01/20/2014
[ 327.540115] task: ffff8803280ccf00 ti: ffff880317c58000 task.ti: ffff880317c58000
[ 327.540184] RIP: 0010:[<ffffffff811a7b55>] [<ffffffff811a7b55>] put_page+0x5/0x50
[ 327.540261] RSP: 0018:ffff880317c5bcf8 EFLAGS: 00010246
[ 327.540313] RAX: 00057ffffffff000 RBX: ffff880616a20000 RCX: 0000000000000000
[ 327.540379] RDX: 0000000000002014 RSI: 00057ffffffff000 RDI: fffffffffffffffe
[ 327.540445] RBP: ffff880317c5bd10 R08: 0000000000000103 R09: 0000000000000000
[ 327.540511] R10: 0000000000000000 R11: 0000000000000000 R12: fffffffffffffffe
[ 327.540576] R13: 0000000000000000 R14: ffff880317c5bd70 R15: ffff880317c5bd50
[ 327.540643] FS: 00007fd230b7f700(0000) GS:ffff880630800000(0000) knlGS:0000000000000000
[ 327.540717] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 327.540771] CR2: fffffffffffffffe CR3: 000000062a2c3000 CR4: 00000000000427e0
[ 327.540837] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 327.540904] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 327.540974] Stack:
[ 327.541008] ffffffffa05d6d0c ffff880616a20000 0000000000000000 ffff880317c5bdc0
[ 327.541093] ffffffffa05ddaa2 0000000000000000 00000000002191bf 00000042f3feab2d
[ 327.541177] 00000042f3feab2d 0000000000000002 0000000000000001 0321000000000000
[ 327.541261] Call Trace:
[ 327.541321] [<ffffffffa05d6d0c>] ? kvm_vcpu_reload_apic_access_page+0x6c/0x80 [kvm]
[ 327.543615] [<ffffffffa05ddaa2>] vcpu_enter_guest+0x3f2/0x10f0 [kvm]
[ 327.545918] [<ffffffffa05e2f10>] kvm_arch_vcpu_ioctl_run+0x2b0/0x5a0 [kvm]
[ 327.548211] [<ffffffffa05e2d02>] ? kvm_arch_vcpu_ioctl_run+0xa2/0x5a0 [kvm]
[ 327.550500] [<ffffffffa05ca845>] kvm_vcpu_ioctl+0x2b5/0x680 [kvm]
[ 327.552768] [<ffffffff810b8d12>] ? creds_are_invalid.part.1+0x12/0x50
[ 327.555069] [<ffffffff810b8d71>] ? creds_are_invalid+0x21/0x30
[ 327.557373] [<ffffffff812d6066>] ? inode_has_perm.isra.49.constprop.65+0x26/0x80
[ 327.559663] [<ffffffff8122d985>] do_vfs_ioctl+0x305/0x530
[ 327.561917] [<ffffffff8122dc51>] SyS_ioctl+0xa1/0xc0
[ 327.564185] [<ffffffff816de829>] system_call_fastpath+0x16/0x1b
[ 327.566480] Code: 0b 31 f6 4c 89 e7 e8 4b 7f ff ff 0f 0b e8 24 fd ff ff e9 a9 fd ff ff 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90 <48> f7 07 00 c0 00 00 55 48 89 e5 75 2a 8b 47 1c 85 c0 74 1e f0

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kvm/x86.c | 2 ++
1 file changed, 2 insertions(+)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6141,6 +6141,8 @@ void kvm_vcpu_reload_apic_access_page(st
return;

page = gfn_to_page(vcpu->kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT);
+ if (is_error_page(page))
+ return;
kvm_x86_ops->set_apic_access_page_addr(vcpu, page_to_phys(page));

/*