On 15.05.2016 11:28, Stefan Weil wrote: > Am 15.05.2016 um 01:13 schrieb Thomas Lamprecht: >> Hi all, >> >> I recently ran into Problems when trying to install some Windows VMs >> this was after an update to QEMU 2.5.1.1, the VM shows Windows loading >> files for the installation, then the "Starting Windows" screen appears >> here it hangs and never continues. >> >> Changing the "-vga" option to cirrus solves this, the installation can >> proceed and finish. When changing back to std (or also qxl, vmware) the >> installed VM also hangs on the "Starting Windows" screen while qemu >> showing a little but no excessive load. >> >> This phenomena appears also with QEMU 2.6.0 but not with 2.6.0-rc4, a >> git bisect shows fd3c136b3e1482cd0ec7285d6bc2a3e6a62c38d7 (vga: make >> sure vga register setup for vbe stays intact (CVE-2016-3712)) as the >> culprit for this regression, as its a fix for a DoS its not an option to >> just revert it, I guess. >> The (short) bisect log is: >> >> git bisect start >> # bad: [bfc766d38e1fae5767d43845c15c79ac8fa6d6af] Update version for v2.6.0 >> release >> git bisect bad bfc766d38e1fae5767d43845c15c79ac8fa6d6af >> # good: [975eb6a547f809608ccb08c221552f666611af25] Update version for >> v2.6.0-rc4 release >> git bisect good 975eb6a547f809608ccb08c221552f666611af25 >> # good: [2068192dcccd8a80dddfcc8df6164cf9c26e0fc4] vga: update vga register >> setup on vbe changes >> git bisect good 2068192dcccd8a80dddfcc8df6164cf9c26e0fc4 >> # bad: [53db932604dfa7bb9241d132e0173894cf54261c] Merge remote-tracking >> branch 'remotes/kraxel/tags/pull-vga-20160509-1' into staging >> git bisect bad 53db932604dfa7bb9241d132e0173894cf54261c >> >> I could reproduce that with QEMU 2.5.1 and QEMU 2.6 on a Debian derivate >> (Promox VE) with 4.4 Kernel and also with QEMU 2.6 on an Arch Linux >> System with a 4.5 Kernel, so it should not be host distro depended. Both >> machines have Intel x86_64 processors. >> The problem should be reproducible with said Versions or a build from >> git including the above mentioned commit (fd3c136) by starting a VM with >> an Windows 7 ISO, e.g.: >> >> Hanging installation >> ./x86_64-softmmu/qemu-system-x86_64 -boot d -cdrom win7.iso -m 1024 >> >> Working installation: >> ./x86_64-softmmu/qemu-system-x86_64 -boot d -cdrom win7.iso -m 1024 -vga >> cirrus >> >> Noteworthy may be that Windows 10 is working, I do not had time to get >> other Windows versions and test them, I'll do that as soon as possible. >> Various Linux system also seems to work fine, at least I did not ran >> into an issue there yet. >> >> I also tried testing with SeaBIOS and OVMF, as initially I had no idea >> what broke, both lead to the same result - without the CVE-2016-3712 fix >> they both work, with not. >> Further, KVM enabled and disabled does not make any difference. >> >> If I can take any further step, e.g. open a bug report at another place >> or help with testing I'd glad to do so. >> >> best regards, >> Thomas > > Hi Thomas, > > thanks for the bug report. > > I added Gerd to the address list, so I'm sure your report will be noticed. > > Bugs can be reported at Launchpad (see > http://wiki.qemu.org/Contribute/ReportABug). > Maybe your report could be posted there, too, so people looking for > known problems > will find it at the well known location. > > Cheers > Stefan >
Hi Stefan, thanks for the response and the directions, I opened bug #1581936 https://bugs.launchpad.net/bugs/1581936 Oh and I noticed that I omitted some of the git bisect log in my previous message, I corrected that in the bug report, also here is the full one: git bisect start # bad: [bfc766d38e1fae5767d43845c15c79ac8fa6d6af] Update version for v2.6.0 release git bisect bad bfc766d38e1fae5767d43845c15c79ac8fa6d6af # good: [975eb6a547f809608ccb08c221552f666611af25] Update version for v2.6.0-rc4 release git bisect good 975eb6a547f809608ccb08c221552f666611af25 # good: [2068192dcccd8a80dddfcc8df6164cf9c26e0fc4] vga: update vga register setup on vbe changes git bisect good 2068192dcccd8a80dddfcc8df6164cf9c26e0fc4 # bad: [53db932604dfa7bb9241d132e0173894cf54261c] Merge remote-tracking branch 'remotes/kraxel/tags/pull-vga-20160509-1' into staging git bisect bad 53db932604dfa7bb9241d132e0173894cf54261c # bad: [fd3c136b3e1482cd0ec7285d6bc2a3e6a62c38d7] vga: make sure vga register setup for vbe stays intact (CVE-2016-3712). git bisect bad fd3c136b3e1482cd0ec7285d6bc2a3e6a62c38d7 # first bad commit: [fd3c136b3e1482cd0ec7285d6bc2a3e6a62c38d7] vga: make sure vga register setup for vbe stays intact (CVE-2016-3712). best regards, Thomas
