From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49866) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bezLD-0002wv-1V for qemu-devel@nongnu.org; Wed, 31 Aug 2016 02:49:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bezL8-00008L-3t for qemu-devel@nongnu.org; Wed, 31 Aug 2016 02:49:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50912) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bezL7-00008A-Ux for qemu-devel@nongnu.org; Wed, 31 Aug 2016 02:49:38 -0400 From: P J P Date: Wed, 31 Aug 2016 12:19:29 +0530 Message-Id: <1472626169-12989-1-git-send-email-ppandit@redhat.com> Subject: [Qemu-devel] [PATCH v2] scsi: check page count while initialising descriptor rings List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Qemu Developers Cc: Paolo Bonzini , Dmitry Fleytman , Tom Victor , Prasad J Pandit From: Prasad J Pandit Vmware Paravirtual SCSI emulation uses command descriptors to process SCSI commands. These descriptors come with their ring buffers. A guest could set the page count for these rings to an arbitrary value, leading to infinite loop or OOB access. Add check to avoid it. Reported-by: Tom Victor Signed-off-by: Prasad J Pandit --- hw/scsi/vmw_pvscsi.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) Update: Moved Request and Confirm rings page count check to the parent function -> pvscsi_on_cmd_setup_rings(). diff --git a/hw/scsi/vmw_pvscsi.c b/hw/scsi/vmw_pvscsi.c index 5116f4a..79aa88c 100644 --- a/hw/scsi/vmw_pvscsi.c +++ b/hw/scsi/vmw_pvscsi.c @@ -160,10 +160,6 @@ pvscsi_ring_init_data(PVSCSIRingInfo *m, PVSCSICmdDescSetupRings *ri) uint32_t req_ring_size, cmp_ring_size; m->rs_pa = ri->ringsStatePPN << VMW_PAGE_SHIFT; - if ((ri->reqRingNumPages > PVSCSI_SETUP_RINGS_MAX_NUM_PAGES) - || (ri->cmpRingNumPages > PVSCSI_SETUP_RINGS_MAX_NUM_PAGES)) { - return -1; - } req_ring_size = ri->reqRingNumPages * PVSCSI_MAX_NUM_REQ_ENTRIES_PER_PAGE; cmp_ring_size = ri->cmpRingNumPages * PVSCSI_MAX_NUM_CMP_ENTRIES_PER_PAGE; txr_len_log2 = pvscsi_log2(req_ring_size - 1); @@ -746,7 +742,7 @@ pvscsi_dbg_dump_tx_rings_config(PVSCSICmdDescSetupRings *rc) trace_pvscsi_tx_rings_num_pages("Confirm Ring", rc->cmpRingNumPages); for (i = 0; i < rc->cmpRingNumPages; i++) { - trace_pvscsi_tx_rings_ppn("Confirm Ring", rc->reqRingPPNs[i]); + trace_pvscsi_tx_rings_ppn("Confirm Ring", rc->cmpRingPPNs[i]); } } @@ -777,12 +773,17 @@ pvscsi_on_cmd_setup_rings(PVSCSIState *s) PVSCSICmdDescSetupRings *rc = (PVSCSICmdDescSetupRings *) s->curr_cmd_data; + if (!rc->reqRingNumPages + || rc->reqRingNumPages > PVSCSI_SETUP_RINGS_MAX_NUM_PAGES + || !rc->cmpRingNumPages + || rc->cmpRingNumPages > PVSCSI_SETUP_RINGS_MAX_NUM_PAGES) { + return PVSCSI_COMMAND_PROCESSING_FAILED; + } + trace_pvscsi_on_cmd_arrived("PVSCSI_CMD_SETUP_RINGS"); pvscsi_dbg_dump_tx_rings_config(rc); - if (pvscsi_ring_init_data(&s->rings, rc) < 0) { - return PVSCSI_COMMAND_PROCESSING_FAILED; - } + pvscsi_ring_init_data(&s->rings, rc); s->rings_info_valid = TRUE; return PVSCSI_COMMAND_PROCESSING_SUCCEEDED; -- 2.5.5