Re: [libvirt] [PATCH] vbox: fix SEGV during dumpxml of a serial port

commit 77a12987a48 changed the "virDomainChrSourceDef source" inside virDomainChrDef to "virDomainChrSourceDefPtr source", and started allocating source inside virDomainChrDefNew(), but vboxDumpSerial() was allocating a virDomainChrDef with a simple VIR_ALLOC(), so source was never initialized, leading to a SEGV any time a serial port was present. The same problem was created in vboxDumpParallel(). This patch changes vboxDumpSerial() and vboxDumpParallel() to use virDomainChrDefNew() instead of VIR_ALLOC(), and makes a cursory attempt to "recover" from OOM afterwards (much of the vbox code was written to assume success, e.g. by having functions return void. Since I have no way to test a more sweeping change to this code, I chose to just short-circuit the rest of the function if virDomainChrDefNew() fails - this is at least one step better than the previous code, which would otherwise end up trying to dereference a NULL def->serials[i] and crash libvirtd. This resolves: https://bugzilla.redhat.com/1536649 --- src/vbox/vbox_common.c | 30 ++++++++++++++++++++++++++---- 1 file changed, 26 insertions(+), 4 deletions(-) diff --git a/src/vbox/vbox_common.c b/src/vbox/vbox_common.c index 33aefabe5..c5fa5f08b 100644 --- a/src/vbox/vbox_common.c +++ b/src/vbox/vbox_common.c @@ -3887,8 +3887,19 @@ vboxDumpSerial(virDomainDefPtr def, vboxDriverPtr data, IMachine *machine, PRUin /* Allocate memory for the serial ports which are enabled */ if ((def->nserials > 0) && (VIR_ALLOC_N(def->serials, def->nserials) >= 0)) { - for (i = 0; i < def->nserials; i++) - ignore_value(VIR_ALLOC(def->serials[i])); + for (i = 0; i < def->nserials; i++) { + def->serials[i] = virDomainChrDefNew(NULL); + if (!def->serials[i]) { + /* there is no provision for returning an error + * (although the libvirtd logs will show an OOM error), + * but we need to at least prevent dereferencing + * def->serials[i] and later (including continuing in + * this function), as it will otherwise cause a SEGV. + */

+ def->nserials = i; + return; + } + } } /* Now get the details about the serial ports here */ @@ -3975,8 +3986,19 @@ vboxDumpParallel(virDomainDefPtr def, vboxDriverPtr data, IMachine *machine, PRU /* Allocate memory for the parallel ports which are enabled */ if ((def->nparallels > 0) && (VIR_ALLOC_N(def->parallels, def->nparallels) >= 0)) { - for (i = 0; i < def->nparallels; i++) - ignore_value(VIR_ALLOC(def->parallels[i])); + for (i = 0; i < def->nparallels; i++) { + def->parallels[i] = virDomainChrDefNew(NULL); + if (!def->parallels[i]) { + /* there is no provision for returning an error + * (although the libvirtd logs will show an OOM error), + * but we need to at least prevent dereferencing + * def->parallels[i] and later (including continuing in + * this function), as it will otherwise cause a SEGV. + */ + def->nparallels = i; + return; + } + } } /* Now get the details about the parallel ports here */