diff options
| author | Michal Luczaj <mhal@rbox.co> | 2023-07-28 03:12:57 +0300 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2023-08-02 23:30:15 +0300 |
| commit | 0d033770d43a7aa36025bcef9a60da7fb750f735 (patch) | |
| tree | 4b8f797d71d917eeea56c77544bed2907e6fa5ef /arch/x86/kvm/x86.c | |
| parent | fdf0eaf11452d72945af31804e2a1048ee1b574c (diff) | |
| download | linux-0d033770d43a7aa36025bcef9a60da7fb750f735.tar.xz | |
KVM: x86: Fix KVM_CAP_SYNC_REGS's sync_regs() TOCTOU issues
In a spirit of using a sledgehammer to crack a nut, make sync_regs() feed
__set_sregs() and kvm_vcpu_ioctl_x86_set_vcpu_events() with kernel's own
copy of data.
Both __set_sregs() and kvm_vcpu_ioctl_x86_set_vcpu_events() assume they
have exclusive rights to structs they operate on. While this is true when
coming from an ioctl handler (caller makes a local copy of user's data),
sync_regs() breaks this contract; a pointer to a user-modifiable memory
(vcpu->run->s.regs) is provided. This can lead to a situation when incoming
data is checked and/or sanitized only to be re-set by a user thread running
in parallel.
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Fixes: 01643c51bfcf ("KVM: x86: KVM_CAP_SYNC_REGS")
Link: https://lore.kernel.org/r/20230728001606.2275586-2-mhal@rbox.co
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86/kvm/x86.c')
| -rw-r--r-- | arch/x86/kvm/x86.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a6b9bea62fb8..0145d844283b 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11777,15 +11777,22 @@ static int sync_regs(struct kvm_vcpu *vcpu) __set_regs(vcpu, &vcpu->run->s.regs.regs); vcpu->run->kvm_dirty_regs &= ~KVM_SYNC_X86_REGS; } + if (vcpu->run->kvm_dirty_regs & KVM_SYNC_X86_SREGS) { - if (__set_sregs(vcpu, &vcpu->run->s.regs.sregs)) + struct kvm_sregs sregs = vcpu->run->s.regs.sregs; + + if (__set_sregs(vcpu, &sregs)) return -EINVAL; + vcpu->run->kvm_dirty_regs &= ~KVM_SYNC_X86_SREGS; } + if (vcpu->run->kvm_dirty_regs & KVM_SYNC_X86_EVENTS) { - if (kvm_vcpu_ioctl_x86_set_vcpu_events( - vcpu, &vcpu->run->s.regs.events)) + struct kvm_vcpu_events events = vcpu->run->s.regs.events; + + if (kvm_vcpu_ioctl_x86_set_vcpu_events(vcpu, &events)) return -EINVAL; + vcpu->run->kvm_dirty_regs &= ~KVM_SYNC_X86_EVENTS; } |