From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Thu, 13 Apr 2017 14:45:24 +0100 Subject: kvm/arm64: use-after-free in kvm_unmap_hva_handler/unmap_stage2_pmds In-Reply-To: References: <20f6c994-d83e-7a6f-9f13-f10287211a6c@arm.com> <9f473bb9-d0eb-6803-1263-75ffef0301fe@redhat.com> <1050c9d8-5813-5df9-29e5-3ab6e61b5de6@arm.com> <20170413093418.GC24027@leverpostej> Message-ID: <20170413134524.GF24027@leverpostej> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Apr 13, 2017 at 01:53:13PM +0200, Andrey Konovalov wrote: > On Thu, Apr 13, 2017 at 11:34 AM, Mark Rutland wrote: > > I had a go at reproducing this on an arm64 board following [1], but so > > far I've had no luck. [...] > Hi Mark, > > You assume that you have KASAN enabled. Yes; I have KASAN_OUTLINE enabled. > Since a few unintended line breaks were added in the email, here's the > program in plaintext: > https://gist.githubusercontent.com/xairy/69864355b5a64f74e7cb445b7325a7df/raw/bdbbbf177dbea13eac0a5ddfa9c3e6c32695b13b/kvm-arm-uaf-log Thanks! > I run it as: > # ./syz-execprog -repeat=0 -collide=false -sandbox=namespace ./kvm-arm-uaf-log Thanks again. Having the exact command was very helpful for sanity-checking my configuration. In the end, it turned out that in my filesystem, /dev/kvm was not accessible by the nobody user, so the executor couldn't open it, and none of the KVM paths were being triggered. > And it takes less than a second to trigger the bug. After having chomd'd /dev/kvm appropriately, I can also reproduce the issue within a second or two, running the same command. Thanks, Mark.