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authorVitaly Kuznetsov <vkuznets@redhat.com>2021-08-27 12:25:14 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2021-09-22 17:33:14 +0300
commit2f9b68f57c6278c322793a06063181deded0ad69 (patch)
treef54c427ef98819dc005623641998a21bd6cfaafe /arch/x86/kvm/ioapic.c
parent7c236b816ef16c2969a88ced658dab667e9dd4ee (diff)
downloadlinux-2f9b68f57c6278c322793a06063181deded0ad69.tar.xz
KVM: x86: Fix stack-out-of-bounds memory access from ioapic_write_indirect()
KASAN reports the following issue: BUG: KASAN: stack-out-of-bounds in kvm_make_vcpus_request_mask+0x174/0x440 [kvm] Read of size 8 at addr ffffc9001364f638 by task qemu-kvm/4798 CPU: 0 PID: 4798 Comm: qemu-kvm Tainted: G X --------- --- Hardware name: AMD Corporation DAYTONA_X/DAYTONA_X, BIOS RYM0081C 07/13/2020 Call Trace: dump_stack+0xa5/0xe6 print_address_description.constprop.0+0x18/0x130 ? kvm_make_vcpus_request_mask+0x174/0x440 [kvm] __kasan_report.cold+0x7f/0x114 ? kvm_make_vcpus_request_mask+0x174/0x440 [kvm] kasan_report+0x38/0x50 kasan_check_range+0xf5/0x1d0 kvm_make_vcpus_request_mask+0x174/0x440 [kvm] kvm_make_scan_ioapic_request_mask+0x84/0xc0 [kvm] ? kvm_arch_exit+0x110/0x110 [kvm] ? sched_clock+0x5/0x10 ioapic_write_indirect+0x59f/0x9e0 [kvm] ? static_obj+0xc0/0xc0 ? __lock_acquired+0x1d2/0x8c0 ? kvm_ioapic_eoi_inject_work+0x120/0x120 [kvm] The problem appears to be that 'vcpu_bitmap' is allocated as a single long on stack and it should really be KVM_MAX_VCPUS long. We also seem to clear the lower 16 bits of it with bitmap_zero() for no particular reason (my guess would be that 'bitmap' and 'vcpu_bitmap' variables in kvm_bitmap_or_dest_vcpus() caused the confusion: while the later is indeed 16-bit long, the later should accommodate all possible vCPUs). Fixes: 7ee30bc132c6 ("KVM: x86: deliver KVM IOAPIC scan request to target vCPUs") Fixes: 9a2ae9f6b6bb ("KVM: x86: Zero the IOAPIC scan request dest vCPUs bitmap") Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210827092516.1027264-7-vkuznets@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/ioapic.c')
-rw-r--r--arch/x86/kvm/ioapic.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
index ff005fe738a4..8c065da73f8e 100644
--- a/arch/x86/kvm/ioapic.c
+++ b/arch/x86/kvm/ioapic.c
@@ -319,8 +319,8 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
unsigned index;
bool mask_before, mask_after;
union kvm_ioapic_redirect_entry *e;
- unsigned long vcpu_bitmap;
int old_remote_irr, old_delivery_status, old_dest_id, old_dest_mode;
+ DECLARE_BITMAP(vcpu_bitmap, KVM_MAX_VCPUS);
switch (ioapic->ioregsel) {
case IOAPIC_REG_VERSION:
@@ -384,9 +384,9 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
irq.shorthand = APIC_DEST_NOSHORT;
irq.dest_id = e->fields.dest_id;
irq.msi_redir_hint = false;
- bitmap_zero(&vcpu_bitmap, 16);
+ bitmap_zero(vcpu_bitmap, KVM_MAX_VCPUS);
kvm_bitmap_or_dest_vcpus(ioapic->kvm, &irq,
- &vcpu_bitmap);
+ vcpu_bitmap);
if (old_dest_mode != e->fields.dest_mode ||
old_dest_id != e->fields.dest_id) {
/*
@@ -399,10 +399,10 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
kvm_lapic_irq_dest_mode(
!!e->fields.dest_mode);
kvm_bitmap_or_dest_vcpus(ioapic->kvm, &irq,
- &vcpu_bitmap);
+ vcpu_bitmap);
}
kvm_make_scan_ioapic_request_mask(ioapic->kvm,
- &vcpu_bitmap);
+ vcpu_bitmap);
} else {
kvm_make_scan_ioapic_request(ioapic->kvm);
}