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When an error occurs during qemu-img convert, several use-after-free errors can
happen which may cause qemu to crash. The problem has been fixed upstream with
commit b91127edd ('qemu-img: wait for convert coroutines to complete') and is
proposed for qemu-stable.
In my own testing, I could not quickly reproduce actual crashes, but using
valgrind I could see errors without the patch. For reproduction, I used a
blkdebug configuration file that would inject a write error after a while:
[inject-error]
event = "write_aio"
sector = "819200"
once = "on"
The test run was performed with a command line like this (note that using
blkdebug as the target requires that an image of the correct size is manually
created and -n is used):
$ valgrind qemu-img convert -npWO qcow2 $SOURCE blkdebug:/tmp/blkdebug.conf:/tmp/test.qcow2
Expected result:
No valgrind errors are reported:
==2576== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Actual result:
Valgrind does report errors:
==2657== ERROR SUMMARY: 8 errors from 2 contexts (suppressed: 0 from 0)
Comment 1Miroslav Rezanina
2017-05-30 15:03:39 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHSA-2017:2392
When an error occurs during qemu-img convert, several use-after-free errors can happen which may cause qemu to crash. The problem has been fixed upstream with commit b91127edd ('qemu-img: wait for convert coroutines to complete') and is proposed for qemu-stable. In my own testing, I could not quickly reproduce actual crashes, but using valgrind I could see errors without the patch. For reproduction, I used a blkdebug configuration file that would inject a write error after a while: [inject-error] event = "write_aio" sector = "819200" once = "on" The test run was performed with a command line like this (note that using blkdebug as the target requires that an image of the correct size is manually created and -n is used): $ valgrind qemu-img convert -npWO qcow2 $SOURCE blkdebug:/tmp/blkdebug.conf:/tmp/test.qcow2 Expected result: No valgrind errors are reported: ==2576== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) Actual result: Valgrind does report errors: ==2657== ERROR SUMMARY: 8 errors from 2 contexts (suppressed: 0 from 0)