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[Qemu-devel] [Bug 1527322] [NEW] undefined behavior issues
From: |
Octoploid |
Subject: |
[Qemu-devel] [Bug 1527322] [NEW] undefined behavior issues |
Date: |
Thu, 17 Dec 2015 16:32:55 -0000 |
Public bug reported:
Building qemu-2.5.0 with -fsanitize=undefined shows, e.g.:
address@hidden linux % qemu-system-x86_64 -s -enable-kvm -net
nic,vlan=0,model=virtio -net user -fsdev
local,security_model=none,id=root,path=/ -device virtio-9p-pci,id=root,fsdev
=root,mount_tag=/dev/root -m 512 -smp 2 -kernel
/usr/src/linux/arch/x86/boot/bzImage -nographic -append "init=/bin/zsh
root=/dev/root console=ttyS0 kgdboc=ttyS0 rootflags=rw,
trans=virtio rootfstype=9p ip=dhcp earlyprintk=ttyS0"
/var/tmp/portage/app-emulation/qemu-2.5.0/work/qemu-2.5.0/exec.c:307:5: runtime
error: variable length array bound evaluates to non-positive value 0
/var/tmp/portage/app-emulation/qemu-2.5.0/work/qemu-2.5.0/hw/i386/kvm/apic.c:37:47:
runtime error: left shift of 15 by 28 places cannot be represented in type
'int'
/var/tmp/portage/app-emulation/qemu-2.5.0/work/qemu-2.5.0/include/qemu/rcu.h:85:21:
runtime error: member access within null pointer of type 'struct
rcu_reader_data'
/var/tmp/portage/app-emulation/qemu-2.5.0/work/qemu-2.5.0/include/qemu/rcu.h:101:5:
runtime error: member access within null pointer of type 'struct
rcu_reader_data'
/var/tmp/portage/app-emulation/qemu-2.5.0/work/qemu-2.5.0/include/qemu/rcu.h:102:8:
runtime error: member access within null pointer of type 'struct
rcu_reader_data'
...
ALSA device list:
No soundcards found.
/var/tmp/portage/app-emulation/qemu-2.5.0/work/qemu-2.5.0/thread-pool.c:246:5:
runtime error: member access within null pointer of type 'struct ThreadPool'
[1] 9295 segmentation fault qemu-system-x86_64 -s -enable-kvm -net
nic,vlan=0,model=virtio -net user
As you can see it segfaults when build with upcoming gcc-6, that is more
aggressive when it comes to undefined behavior.
The compiler just assumes that "this" can never be NULL and optimizes
accordingly.
** Affects: qemu
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1527322
Title:
undefined behavior issues
Status in QEMU:
New
Bug description:
Building qemu-2.5.0 with -fsanitize=undefined shows, e.g.:
address@hidden linux % qemu-system-x86_64 -s -enable-kvm -net
nic,vlan=0,model=virtio -net user -fsdev
local,security_model=none,id=root,path=/ -device virtio-9p-pci,id=root,fsdev
=root,mount_tag=/dev/root -m 512 -smp 2 -kernel
/usr/src/linux/arch/x86/boot/bzImage -nographic -append "init=/bin/zsh
root=/dev/root console=ttyS0 kgdboc=ttyS0 rootflags=rw,
trans=virtio rootfstype=9p ip=dhcp earlyprintk=ttyS0"
/var/tmp/portage/app-emulation/qemu-2.5.0/work/qemu-2.5.0/exec.c:307:5:
runtime error: variable length array bound evaluates to non-positive value 0
/var/tmp/portage/app-emulation/qemu-2.5.0/work/qemu-2.5.0/hw/i386/kvm/apic.c:37:47:
runtime error: left shift of 15 by 28 places cannot be represented in type
'int'
/var/tmp/portage/app-emulation/qemu-2.5.0/work/qemu-2.5.0/include/qemu/rcu.h:85:21:
runtime error: member access within null pointer of type 'struct
rcu_reader_data'
/var/tmp/portage/app-emulation/qemu-2.5.0/work/qemu-2.5.0/include/qemu/rcu.h:101:5:
runtime error: member access within null pointer of type 'struct
rcu_reader_data'
/var/tmp/portage/app-emulation/qemu-2.5.0/work/qemu-2.5.0/include/qemu/rcu.h:102:8:
runtime error: member access within null pointer of type 'struct
rcu_reader_data'
...
ALSA device list:
No soundcards found.
/var/tmp/portage/app-emulation/qemu-2.5.0/work/qemu-2.5.0/thread-pool.c:246:5:
runtime error: member access within null pointer of type 'struct ThreadPool'
[1] 9295 segmentation fault qemu-system-x86_64 -s -enable-kvm -net
nic,vlan=0,model=virtio -net user
As you can see it segfaults when build with upcoming gcc-6, that is more
aggressive when it comes to undefined behavior.
The compiler just assumes that "this" can never be NULL and optimizes
accordingly.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1527322/+subscriptions
- [Qemu-devel] [Bug 1527322] [NEW] undefined behavior issues,
Octoploid <=