From: Paolo Bonzini <pbonzini@redhat.com>
To: Joe Moriarty <joe.moriarty@oracle.com>,
rkrcmar@redhat.com, kvm@vger.kernel.org,
Xiao Guangrong <xiaoguangrong@tencent.com>
Subject: Re: [PATCH v1 1/1] KVM: X86: NULL pointer dereference [null-pointer-deref] (CWE 476) problem
Date: Wed, 14 Feb 2018 18:33:52 +0100 [thread overview]
Message-ID: <06fe1847-28a8-7457-e0c8-81ede5b68c8f@redhat.com> (raw)
In-Reply-To: <6e222b28-5c6e-5a57-1eb4-a9d8cc2b7dbe@oracle.com>
On 14/02/2018 17:55, Joe Moriarty wrote:
>>
> Hi Paolo,
>
> Thank you for the review. I wasn't sure if the change I proposed was
> correct or not. I will take your suggestion of posting to the mailing
> list instead of as a patch the next time I encounter a situation like
> this again. In the meantime, I will look at doing your suggestion of
> passing kvm_memory_slot down to gfn_to_rmap() and the other functions
> you pointed out above for the next version of the patch.
It's not easy, but I can send you a box of beers if you get round to it.
Note that I'm still not sure how the NULL pointer dereference can
happen, and you didn't include more output from your tool, so you might
be wasting your time after all...
Anyway, I would start basically by mapping the paths from try_async_pf's
callers to mmu_set_spte and from there to rmap_add.
On the other hand, in the rmap_remove path, you probably should just
exit immediately if slot is NULL. (Guangrong, do you have any idea why
we don't zap SPTEs in kvm_arch_free_memslot?)
Paolo
next prev parent reply other threads:[~2018-02-14 17:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-13 18:26 [PATCH v1 0/1] Parfait changes Joe Moriarty
2018-02-13 18:26 ` [PATCH v1 1/1] KVM: X86: NULL pointer dereference [null-pointer-deref] (CWE 476) problem Joe Moriarty
2018-02-14 16:28 ` Paolo Bonzini
2018-02-14 16:55 ` Joe Moriarty
2018-02-14 17:33 ` Paolo Bonzini [this message]
2018-02-14 18:14 ` Joe Moriarty
2018-02-14 21:42 ` Paolo Bonzini
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