On Thu, Apr 13, 2017 at 05:43:34PM +0200, Max Reitz wrote: > The block layer takes care of removing the bs->file child if the block > driver's bdrv_open()/bdrv_file_open() implementation fails. The block > driver therefore does not need to do so, and indeed should not unless it > sets bs->file to NULL afterwards -- because if this is not done, the > bdrv_unref_child() in bdrv_open_inherit() will dereference the freed > memory block at bs->file afterwards, which is not good. > > We can now decide whether to add a "bs->file = NULL;" after each of the > offending bdrv_unref_child() invocations, or just drop them altogether. > The latter is simpler, so let's do that. > > Cc: qemu-stable <qemu-sta...@nongnu.org> > Signed-off-by: Max Reitz <mre...@redhat.com> > --- > It's an issue only in blkdebug, blkreplace and blkverify, and only when > an error occurs in their open functions; therefore I think this is fine > to delay until 2.10. > > However, it *is* a use-after-free newly introduced in 2.9, so that's > where the question mark comes from... > --- > block/blkdebug.c | 4 +--- > block/blkreplay.c | 3 --- > block/blkverify.c | 3 --- > 3 files changed, 1 insertion(+), 9 deletions(-)
Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
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