| Message ID | 20240627-bug5-v2-1-2c63f7ee6739@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] kvm: Fix warning in__kvm_gpc_refresh | expand |
On 27/06/2024 16:03, Pei Li wrote: > Check for invalid hva address stored in data and return -EINVAL before > calling into __kvm_gpc_activate(). > > Reported-by: syzbot+fd555292a1da3180fc82@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=fd555292a1da3180fc82 > Tested-by: syzbot+fd555292a1da3180fc82@syzkaller.appspotmail.com > Signed-off-by: Pei Li <peili.dev@gmail.com> > --- > 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 and return -EINVAL before > calling __kvm_gpc_activate(). > > syzbot has tested the proposed patch and the reproducer did not trigger > any issue. > > Tested on: > > commit: afcd4813 Merge tag 'mm-hotfixes-stable-2024-06-26-17-2.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1427e301980000 > 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=13838f3e980000 > > Note: testing is done by a robot and is best-effort only. > --- > Changes in v2: > - Adapted Sean's suggestion to check for valid address before calling > into __kvm_gpc_activate(). > - Link to v1: https://lore.kernel.org/r/20240625-bug5-v1-1-e072ed5fce85@gmail.com > --- > arch/x86/kvm/xen.c | 2 +- > virt/kvm/pfncache.c | 3 +++ > 2 files changed, 4 insertions(+), 1 deletion(-) > Reviewed-by: Paul Durrant <paul@xen.org>
On Fri, 2024-06-28 at 15:25 +0100, Paul Durrant wrote: > On 27/06/2024 16:03, Pei Li wrote: > > Check for invalid hva address stored in data and return -EINVAL before > > calling into __kvm_gpc_activate(). > > > > Reported-by: syzbot+fd555292a1da3180fc82@syzkaller.appspotmail.com > > Closes: https://syzkaller.appspot.com/bug?extid=fd555292a1da3180fc82 > > Tested-by: syzbot+fd555292a1da3180fc82@syzkaller.appspotmail.com > > Signed-off-by: Pei Li <peili.dev@gmail.com> > > --- > > 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 and return -EINVAL before > > calling __kvm_gpc_activate(). > > > > syzbot has tested the proposed patch and the reproducer did not trigger > > any issue. > > > > Tested on: > > > > commit: afcd4813 Merge tag 'mm-hotfixes-stable-2024-06-26-17-2.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=1427e301980000 > > 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=13838f3e980000 > > > > Note: testing is done by a robot and is best-effort only. > > --- > > Changes in v2: > > - Adapted Sean's suggestion to check for valid address before calling > > into __kvm_gpc_activate(). > > - Link to v1: https://lore.kernel.org/r/20240625-bug5-v1-1-e072ed5fce85@gmail.com > > --- > > arch/x86/kvm/xen.c | 2 +- > > virt/kvm/pfncache.c | 3 +++ > > 2 files changed, 4 insertions(+), 1 deletion(-) > > > > Reviewed-by: Paul Durrant <paul@xen.org> Reviewed-by: David Woodhouse <dwmw@amazon.co.uk> Thanks.
On Thu, 27 Jun 2024 08:03:56 -0700, Pei Li wrote: > Check for invalid hva address stored in data and return -EINVAL before > calling into __kvm_gpc_activate(). Applied to kvm-x86 fixes, thanks! [1/1] kvm: Fix warning in__kvm_gpc_refresh https://github.com/kvm-x86/linux/commit/ebbdf37ce9ab -- https://github.com/kvm-x86/linux/tree/next
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index f65b35a05d91..67bb4e89c399 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -741,7 +741,7 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data) } else { void __user * hva = u64_to_user_ptr(data->u.shared_info.hva); - if (!PAGE_ALIGNED(hva) || !access_ok(hva, PAGE_SIZE)) { + if (!PAGE_ALIGNED(hva)) { r = -EINVAL; } else if (!hva) { kvm_gpc_deactivate(&kvm->arch.xen.shinfo_cache); diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c index e3453e869e92..f0039efb9e1e 100644 --- a/virt/kvm/pfncache.c +++ b/virt/kvm/pfncache.c @@ -430,6 +430,9 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len) int kvm_gpc_activate_hva(struct gfn_to_pfn_cache *gpc, unsigned long uhva, unsigned long len) { + if (!access_ok((void __user *)uhva, len)) + return -EINVAL; + return __kvm_gpc_activate(gpc, INVALID_GPA, uhva, len); }