[RFC PATCH 2/2] integrity: double check iint_cache was initialized
dvyukov at google.com
Mon Mar 22 07:53:47 UTC 2021
On Mon, Mar 22, 2021 at 8:11 AM Tetsuo Handa
<penguin-kernel at i-love.sakura.ne.jp> wrote:
> On 2021/03/20 5:03, Mimi Zohar wrote:
> > The integrity's "iint_cache" is initialized at security_init(). Only
> > after an IMA policy is loaded, which is initialized at late_initcall,
> > is a file's integrity status stored in the "iint_cache".
> > All integrity_inode_get() callers first verify that the IMA policy has
> > been loaded, before calling it. Yet for some reason, it is still being
> > called, causing a NULL pointer dereference.
> > As reported by Dmitry Vyukov:
> > in qemu:
> > qemu-system-x86_64 -enable-kvm -machine q35,nvdimm -cpu
> > max,migratable=off -smp 4 -m 4G,slots=4,maxmem=16G -hda
> > wheezy.img -kernel arch/x86/boot/bzImage -nographic -vga std
> > -soundhw all -usb -usbdevice tablet -bt hci -bt device:keyboard
> > -net user,host=10.0.2.10,hostfwd=tcp::10022-:22 -net
> > nic,model=virtio-net-pci -object
> > memory-backend-file,id=pmem1,share=off,mem-path=/dev/zero,size=64M
> > -device nvdimm,id=nvdimm1,memdev=pmem1 -append "console=ttyS0
> > root=/dev/sda earlyprintk=serial rodata=n oops=panic panic_on_warn=1
> > panic=86400 lsm=smack numa=fake=2 nopcid dummy_hcd.num=8" -pidfile
> > vm_pid -m 2G -cpu host
> I tried similar command line (without "-enable-kvm" and without "-cpu host"
> as I'm running from VMware, without "-soundhw all", without "-machine q35,nvdimm"
> and "-device nvdimm,id=nvdimm1,memdev=pmem1" etc.) on 5.12-rc4. While I was finally
> able to hit similar crash when I used "-smp 1" instead of "-smp 4", I suspect
> this is not a integrity module's problem but a memory initialization/corruption
> problem, for I got various different crashes (INT3) at memory allocation when
> I was trimming command line options trying to reproduce the same crash.
> Dmitry, do you get different crashes by changing command line arguments?
No, I have not seen any other crashes, one the reported one.
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