Re: [libvirt] [PATCH 3/3] util: storage: Improve error message when requesting image above 'start'

On Wed, Apr 22, 2015 at 02:15:21PM +0200, Peter Krempa wrote: >On Wed, Apr 22, 2015 at 14:09:18 +0200, Martin Kletzander wrote: >> On Tue, Apr 21, 2015 at 05:52:14PM +0200, Peter Krempa wrote: >> >When a user would specify a backing chain index that is above the start >> >point libvirt would report a rather unhelpful error: >> > >> >invalid argument: could not find backing store 1 in chain for 'sub/link2' >> > >> >This patch adds an explicit check that the index is below start point in >> >the backing store and reports the following error if not: >> > >> >invalid argument: requested backing store index 1 is above 'sub/../qcow2' in chain for 'sub/link2' >> > >> >Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1177062 >> >--- >> > src/util/virstoragefile.c | 9 +++++++++ >> > 1 file changed, 9 insertions(+) >> > >> >diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c >> >index c9d3977..2a2f238 100644 >> >--- a/src/util/virstoragefile.c >> >+++ b/src/util/virstoragefile.c >> >@@ -1341,6 +1341,15 @@ virStorageFileChainLookup(virStorageSourcePtr chain, >> > *parent = startFrom; >> > } >> > >> >+ if (idx && idx < i) { >> >+ virReportError(VIR_ERR_INVALID_ARG, >> >+ _("requested backing store index %u is above '%s' " >> >+ "in chain for '%s'"), >> >+ idx, NULLSTR(startFrom->path), NULLSTR(start)); >> >> Possible crasher: startFrom can be NULL here, rather move the check >> into the previous block where the parent is being set when found (idx >> can't be < i when there is no startFrom anyway). You can then avoid >> cleaning up the *parent here -+ >> | >> +-----------+ >> | >> v > >Actually right at the beginning of the function @parent gets filled by a >pointer to a local virStorageSource pointer (stack allocated) in case >the caller passed NULL as @parent. This allows to use the variable since >it is used in the lookup loop even if the user doesn't pass it. > Yeah, but I was talking about startFrom->path sigsegv-ing if startFrom == NULL. >Don't worry, I had the same thought when I wrote the condition :) > Don't worry, I know people sometime misunderstand me ;)