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| author | Paolo Bonzini <pbonzini@redhat.com> | 2015-09-22 10:15:59 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2015-09-25 10:31:29 +0200 |
| commit | 58c95070da3a504fbeca7939435bbb062cb96ea3 (patch) | |
| tree | a22ad61caee779b2f20fca6b87a5589a10507685 | |
| parent | 6fec21449a62702a582cecbb0b351363e039c95e (diff) | |
| download | linux-58c95070da3a504fbeca7939435bbb062cb96ea3.tar.gz linux-58c95070da3a504fbeca7939435bbb062cb96ea3.tar.bz2 linux-58c95070da3a504fbeca7939435bbb062cb96ea3.zip | |
KVM: x86: fix off-by-one in reserved bits check
29ecd6601904 ("KVM: x86: avoid uninitialized variable warning",
2015-09-06) introduced a not-so-subtle problem, which probably
escaped review because it was not part of the patch context.
Before the patch, leaf was always equal to iterator.level. After,
it is equal to iterator.level - 1 in the call to is_shadow_zero_bits_set,
and when is_shadow_zero_bits_set does another "-1" the check on
reserved bits becomes incorrect. Using "iterator.level" in the call
fixes this call trace:
WARNING: CPU: 2 PID: 17000 at arch/x86/kvm/mmu.c:3385 handle_mmio_page_fault.part.93+0x1a/0x20 [kvm]()
Modules linked in: tun sha256_ssse3 sha256_generic drbg binfmt_misc ipv6 vfat fat fuse dm_crypt dm_mod kvm_amd kvm crc32_pclmul aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd fam15h_power amd64_edac_mod k10temp edac_core amdkfd amd_iommu_v2 radeon acpi_cpufreq
[...]
Call Trace:
dump_stack+0x4e/0x84
warn_slowpath_common+0x95/0xe0
warn_slowpath_null+0x1a/0x20
handle_mmio_page_fault.part.93+0x1a/0x20 [kvm]
tdp_page_fault+0x231/0x290 [kvm]
? emulator_pio_in_out+0x6e/0xf0 [kvm]
kvm_mmu_page_fault+0x36/0x240 [kvm]
? svm_set_cr0+0x95/0xc0 [kvm_amd]
pf_interception+0xde/0x1d0 [kvm_amd]
handle_exit+0x181/0xa70 [kvm_amd]
? kvm_arch_vcpu_ioctl_run+0x68b/0x1730 [kvm]
kvm_arch_vcpu_ioctl_run+0x6f6/0x1730 [kvm]
? kvm_arch_vcpu_ioctl_run+0x68b/0x1730 [kvm]
? preempt_count_sub+0x9b/0xf0
? mutex_lock_killable_nested+0x26f/0x490
? preempt_count_sub+0x9b/0xf0
kvm_vcpu_ioctl+0x358/0x710 [kvm]
? __fget+0x5/0x210
? __fget+0x101/0x210
do_vfs_ioctl+0x2f4/0x560
? __fget_light+0x29/0x90
SyS_ioctl+0x4c/0x90
entry_SYSCALL_64_fastpath+0x16/0x73
---[ end trace 37901c8686d84de6 ]---
Reported-by: Borislav Petkov <bp@alien8.de>
Tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/mmu.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 6f207637e437..ff606f507913 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -3322,7 +3322,7 @@ walk_shadow_page_get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep) break; reserved |= is_shadow_zero_bits_set(&vcpu->arch.mmu, spte, - leaf); + iterator.level); } walk_shadow_page_lockless_end(vcpu); |