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> 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); } -- 2.26.3
