Re: [x86, kaslr] PANIC: early exception 0e rip 10:ffffffff8ae04c6e error 0 cr2 ffffffff81972b28

Fengguang Wu
2014-01-16T00:05:20Z

On Wed, Jan 15, 2014 at 02:32:52PM -0800, Kees Cook wrote:
> On Wed, Jan 15, 2014 at 4:24 AM, Fengguang Wu <fengguang.wu@intel.com> wrote:
> > Kees,
> >
> > This script can reproduce the problem. Please modify the -initrd line
> > before use.
> >
> > Usage:
> > ./kvm-0day.sh vmlinuz-3.12.0-rc4-00008-g6e6a493
> >
> > #!/bin/bash
> >
> > kernel=$1
> >
> > kvm=(
> > qemu-system-x86_64 -cpu kvm64 -enable-kvm
> > -kernel $kernel
> > -initrd /kernel-tests/initrd/yocto-minimal-x86_64.cgz
> > # -initrd /kernel-tests/initrd/yocto-minimal-i386.cgz
> > # -initrd /kernel-tests/initrd/quantal-core-i386.cgz
> > # -initrd /kernel-tests/initrd/quantal-core-x86_64.cgz
> > -smp 2
> > -m 256M
> > -net nic,vlan=0,macaddr=00:00:00:00:00:00,model=virtio
> > -net user,vlan=0
> > -net nic,vlan=1,model=e1000
> > -net user,vlan=1
> > -boot order=nc
> > -no-reboot
> > -watchdog i6300esb
> > -serial stdio
> > -display none
> > -monitor null
> > )
> >
> > append=(
> > debug
> > sched_debug
> > apic=debug
> > ignore_loglevel
> > # dyndbg=\"func kobject_release +p\"
> > sysrq_always_enabled
> > panic=10
> > prompt_ramdisk=0
> > earlyprintk=ttyS0,115200
> > console=ttyS0,115200
> > console=tty0
> > vga=normal
> > root=/dev/ram0
> > rw
> > )
> >
> > "${kvm[@]}" --append "${append[*]}"
>
> Thanks! I'm using your yocto image and this script, but I still am not
> encountering the problem. I'm building next-20140114 using the
> randconfig you sent in the original report. It looks like you're built
> against a slightly different kernel version? Is there some way you can
> push the tree you're building to git somewhere for me to fetch?

Kees, judging from the below bisect log, next-20140114 boots fine.
If you still have access to commit 82fa9637a2ba285bcc7c5050c73010b2c1b3d803
in the tip tree, it's the right one to test.

git bisect start 6e6a4932b0f569b1a5bb4fcbf5dde1b1a42f01bb v3.11 --
git bisect good b7c09ad4014e3678e8cc01fdf663c9f43b272dc6 # 22:54 20+ 0 Merge branch 'for-linus' of
git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs
git bisect good 654fdd041227d7de1594baa61c58f2c87bd0640f # 23:15 20+ 1 Merge branch 'x86-urgent-for-linus' of
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect good 0b936842c86392dad2c880539e824881e5d8ba77 # 23:35 20+ 0 Merge
git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc
git bisect good 3dbecf0aa9692cffbb71313a380c0ecc606c5920 # 23:56 20+ 0 Merge tag 'xfs-for-linus-v3.12-rc4' of
git://oss.sgi.com/xfs/xfs
git bisect good 13caa8ed93513dd216ede0c84d833e39fc2e3e2a # 00:06 20+ 0 Merge
git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending
git bisect good 8ab3820fd5b2896d66da7bb2a906bc382e63e7bc # 00:18 20+ 0 x86, kaslr: Return location from decompress_kernel
git bisect bad 82fa9637a2ba285bcc7c5050c73010b2c1b3d803 # 00:18 0- 988 x86, kaslr: Select random position from e820 maps
git bisect good 5bfce5ef55cbe78ee2ee6e97f2e26a8a582008f3 # 00:27 20+ 52 x86, kaslr: Provide randomness functions
# first bad commit: [82fa9637a2ba285bcc7c5050c73010b2c1b3d803] x86, kaslr: Select random position from e820 maps
git bisect good 5bfce5ef55cbe78ee2ee6e97f2e26a8a582008f3 # 00:39 60+ 52 x86, kaslr: Provide randomness functions
git bisect good 1955a14a5ba6e3c3b11117812d11dc550ccc37ae # 00:59 60+ 149 Add linux-next specific files for 20140110
git bisect good 8bcd53c437d5fdd04fddd8c7e29ecbdc682e7ce1 # 01:22 60+ 60 Revert "x86, kaslr: Select random position from e820
maps"
git bisect good a6da83f98267bc8ee4e34aa899169991eb0ceb93 # 01:38 60+ 42 Merge branch 'merge' of
git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc
git bisect good cf1c1d193e37b9f79eedddc6bbd71b9f5f9751e5 # 01:45 72+ 1972 Add linux-next specific files for 20140114

Thanks,
Fengguang