On Mon, Mar 22, 2021 at 8:11 AM Tetsuo Handa
[off-list ref] wrote:

On 2021/03/20 5:03, Mimi Zohar wrote:

quoted

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.