Commit 7f61f469 authored by Prasad J Pandit's avatar Prasad J Pandit Committed by Paolo Bonzini
Browse files

vmw_pvscsi: check page count while initialising descriptor rings 



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: default avatarTom Victor <vv474172261@gmail.com>
Signed-off-by: default avatarPrasad J Pandit <pjp@fedoraproject.org>
Message-Id: <1472626169-12989-1-git-send-email-ppandit@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 48b62063

hw/scsi/vmw_pvscsi.c

+9 −10
Original line number Diff line number Diff line
@@ -152,7 +152,7 @@ pvscsi_log2(uint32_t input) 
    return log;

}



static int

static void

pvscsi_ring_init_data(PVSCSIRingInfo *m, PVSCSICmdDescSetupRings *ri)

{

    int i;
@@ -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);
@@ -195,8 +191,6 @@ pvscsi_ring_init_data(PVSCSIRingInfo *m, PVSCSICmdDescSetupRings *ri) 


    /* Flush ring state page changes */

    smp_wmb();



    return 0;

}



static int
@@ -746,7 +740,7 @@ 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]);

    }

}
@@ -779,11 +773,16 @@ pvscsi_on_cmd_setup_rings(PVSCSIState *s) 


    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) {

    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;

    }



    pvscsi_dbg_dump_tx_rings_config(rc);

    pvscsi_ring_init_data(&s->rings, rc);



    s->rings_info_valid = TRUE;

    return PVSCSI_COMMAND_PROCESSING_SUCCEEDED;

}