** Description changed: + [Impact] + + * enabling vvfat with rw set breaks qemu once it writes something + + * Fix is a backport of a small upstream fix + + [Test Case] + + * 1. get a guest that works (via uvtoools-libvirt or whatever you prever) + * 2. get the qemu commandline that it is started with, in my case: + $ sudo kvm -m 1024 -drive file=/dev/sdb,format=raw,cache=none,index=0,media=disk + * 3. create a dir and add a file to check to share in vvfat mode later + $ mkdir /tmp/sharevvfat + $ echo host > /tmp/sharevvfat/hostfoo + * 4. shutdown guest and start it again with the path as vvfat set to share rw mode, to do so append + -drive format=vvfat,file=fat:rw:/tmp/sharevvfat/,if=virtio + * in the guest mount the block device and write to it + $ mount /dev/vdc1 /mnt + $ echo guest > /mnt/guestfoo + $ sync + + Currently crashes: + qemu-system-x86_64: /build/qemu-iZpOAh/qemu-2.5+dfsg/block/vvfat.c:2290: commit_direntries: Assertion `!strncmp(s->directory.pointer, "QEMU", 4)' failed. Aborted (core dumped) + + Expected: work to write files from guest and getting no fails/crashes + + + [Regression Potential] + + * I'd consider the potential next-to-none for general qemu/kvm use cases + and low for cases using vvfat for the following reasons: + * The fix is local and only executed in vvfat code, so affecting other + qemu use cases should be next to impossible + * code is upstream and in further Ubuntu Releases quite a while without + issues showing up + * General regression checks showed no issue + + + [Other Info] + + * n/a + + --- + + Hi guys, I'm getting this qemu crash message: >>> qemu-system-x86_64: /build/qemu-TziMIO/qemu-2.5+dfsg/block/vvfat.c:2290: commit_direntries: Assertion `!strncmp(s->directory.pointer, "QEMU", 4)' failed. >>> Aborted (core dumped) when launching qemu with this options for a VVFAT drive: >>> -drive file=fat:rw:./ROOT,if=virtio (same happens when using cache=none and/or if=ide) "uname -a" system info is: >>> Linux RJZ-WRK-LNX 4.4.0-72-generic #93-Ubuntu SMP Fri Mar 31 14:07:41 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux and "qemu --version" is: >>> QEMU emulator version 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.10), Copyright (c) 2003-2008 Fabrice Bellard Not sure what logs to attach but I'll be glad to upload whatever needed. Thanks in advance for you help, Rolando
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1684239 Title: vvfat core dump when enabling RW To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1684239/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
