On 4/18/21 7:30 AM, Philippe Mathieu-Daudé wrote: > From: Michael Tokarev <m...@tls.msk.ru> > > While processing SCSI i/o requests in mptsas_process_scsi_io_request(), > the Megaraid emulator appends new MPTSASRequest object 'req' to > the 's->pending' queue. In case of an error, this same object gets > dequeued in mptsas_free_request() only if SCSIRequest object > 'req->sreq' is initialised. This may lead to a use-after-free issue. > > Since s->pending is actually not used, simply remove it from > MPTSASState. > > Cc: qemu-sta...@nongnu.org > Signed-off-by: Michael Tokarev <m...@tls.msk.ru> > Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com> > Message-Id: <20210416102243.1293871-1-...@msgid.tls.msk.ru>
Suggested-by: Paolo Bonzini <pbonz...@redhat.com> > Reported-by: Cheolwoo Myung <cwmy...@snu.ac.kr> > BugLink: https://bugs.launchpad.net/qemu/+bug/1914236 (CVE-2021-3392) > Fixes: e351b826112 ("hw: Add support for LSI SAS1068 (mptsas) device") > [PMD: Reworded description, added more tags] > Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com> > --- > Supersedes: <20210416102243.1293871-1-...@msgid.tls.msk.ru> > > MJT patch: > https://www.mail-archive.com/qemu-devel@nongnu.org/msg799236.html > > Since rc4 is soon, I'm directly respining his patch with my comments > addressed. > > This is not a new regression (present since QEMU v2.6.0) but is a > CVE... > > PJP first patch: > https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg02660.html > --- > hw/scsi/mptsas.h | 1 - > hw/scsi/mptsas.c | 4 ---- > 2 files changed, 5 deletions(-) > > diff --git a/hw/scsi/mptsas.h b/hw/scsi/mptsas.h > index b85ac1a5fcc..c046497db71 100644 > --- a/hw/scsi/mptsas.h > +++ b/hw/scsi/mptsas.h > @@ -79,7 +79,6 @@ struct MPTSASState { > uint16_t reply_frame_size; > > SCSIBus bus; > - QTAILQ_HEAD(, MPTSASRequest) pending; > }; > > void mptsas_fix_scsi_io_endianness(MPIMsgSCSIIORequest *req); > diff --git a/hw/scsi/mptsas.c b/hw/scsi/mptsas.c > index 7416e787061..5abbc742aaf 100644 > --- a/hw/scsi/mptsas.c > +++ b/hw/scsi/mptsas.c > @@ -257,7 +257,6 @@ static void mptsas_free_request(MPTSASRequest *req) > req->sreq->hba_private = NULL; > scsi_req_unref(req->sreq); > req->sreq = NULL; > - QTAILQ_REMOVE(&s->pending, req, next); > } > qemu_sglist_destroy(&req->qsg); > g_free(req); > @@ -303,7 +302,6 @@ static int mptsas_process_scsi_io_request(MPTSASState *s, > } > > req = g_new0(MPTSASRequest, 1); > - QTAILQ_INSERT_TAIL(&s->pending, req, next); > req->scsi_io = *scsi_io; > req->dev = s; > > @@ -1319,8 +1317,6 @@ static void mptsas_scsi_realize(PCIDevice *dev, Error > **errp) > > s->request_bh = qemu_bh_new(mptsas_fetch_requests, s); > > - QTAILQ_INIT(&s->pending); > - > scsi_bus_new(&s->bus, sizeof(s->bus), &dev->qdev, &mptsas_scsi_info, > NULL); > } > >