Check for invalid hva address stored in data before calling kvm_gpc_activate_hva() instead of only compare with 0. Reported-by: syzbot+fd555292a1da3180fc82@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=fd555292a1da3180fc82 Tested-by: syzbot+fd555292a1da3180fc82@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Pei Li <peili.dev@xxxxxxxxx> --- Syzbot reports a warning message in __kvm_gpc_refresh(). This warning requires at least one of gpa and uhva to be valid. WARNING: CPU: 0 PID: 5090 at arch/x86/kvm/../../../virt/kvm/pfncache.c:259 __kvm_gpc_refresh+0xf17/0x1090 arch/x86/kvm/../../../virt/kvm/pfncache.c:259 We are calling it from kvm_gpc_activate_hva(). This function always calls __kvm_gpc_activate() with INVALID_GPA. Thus, uhva must be valid to disable this warning. This patch checks for invalid hva address as well instead of only comparing hva with 0 before calling kvm_gpc_activate_hva() syzbot has tested the proposed patch and the reproducer did not trigger any issue. Tested on: commit: 55027e68 Merge tag 'input-for-v6.10-rc5' of git://git... git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=16ea803a980000 kernel config: https://syzkaller.appspot.com/x/.config?x=e40800950091403a dashboard link: https://syzkaller.appspot.com/bug?extid=fd555292a1da3180fc82 compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 patch: https://syzkaller.appspot.com/x/patch.diff?x=16eeb53e980000 Note: testing is done by a robot and is best-effort only. --- arch/x86/kvm/xen.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index f65b35a05d91..de5f34492405 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -881,7 +881,7 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) r = kvm_gpc_activate(&vcpu->arch.xen.vcpu_info_cache, data->u.gpa, sizeof(struct vcpu_info)); } else { - if (data->u.hva == 0) { + if (data->u.hva == 0 || kvm_is_error_hva(data->u.hva)) { kvm_gpc_deactivate(&vcpu->arch.xen.vcpu_info_cache); r = 0; break; --- base-commit: 2bfcfd584ff5ccc8bb7acde19b42570414bf880b change-id: 20240625-bug5-5d332b5e5161 Best regards, -- Pei Li <peili.dev@xxxxxxxxx>
