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Message-ID: <a78f803e7c253b981c94f30a5322003af86ee5b4.camel@infradead.org>
Date: Fri, 28 Jun 2024 16:00:22 +0100
From: David Woodhouse <dwmw2@...radead.org>
To: paul@....org, Pei Li <peili.dev@...il.com>, Sean Christopherson
<seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, Thomas Gleixner
<tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov
<bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>, Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>, Bill Wendling
<morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
skhan@...uxfoundation.org, linux-kernel-mentees@...ts.linuxfoundation.org,
syzkaller-bugs@...glegroups.com, llvm@...ts.linux.dev,
syzbot+fd555292a1da3180fc82@...kaller.appspotmail.com
Subject: Re: [PATCH v2] kvm: Fix warning in__kvm_gpc_refresh
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@...kaller.appspotmail.com
> > Closes: https://syzkaller.appspot.com/bug?extid=fd555292a1da3180fc82
> > Tested-by: syzbot+fd555292a1da3180fc82@...kaller.appspotmail.com
> > Signed-off-by: Pei Li <peili.dev@...il.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@....org>
Reviewed-by: David Woodhouse <dwmw@...zon.co.uk>
Thanks.
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