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: Tom Victor <vv474172261@gmail.com> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> Message-Id: <1472626169-12989-1-git-send-email-ppandit@redhat.com> Cc: qemu-stable@nongnu.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@ -152,7 +152,7 @@ pvscsi_log2(uint32_t input)
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return log;
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}
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static int
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static void
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pvscsi_ring_init_data(PVSCSIRingInfo *m, PVSCSICmdDescSetupRings *ri)
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{
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int i;
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@ -160,10 +160,6 @@ pvscsi_ring_init_data(PVSCSIRingInfo *m, PVSCSICmdDescSetupRings *ri)
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uint32_t req_ring_size, cmp_ring_size;
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m->rs_pa = ri->ringsStatePPN << VMW_PAGE_SHIFT;
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if ((ri->reqRingNumPages > PVSCSI_SETUP_RINGS_MAX_NUM_PAGES)
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|| (ri->cmpRingNumPages > PVSCSI_SETUP_RINGS_MAX_NUM_PAGES)) {
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return -1;
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}
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req_ring_size = ri->reqRingNumPages * PVSCSI_MAX_NUM_REQ_ENTRIES_PER_PAGE;
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cmp_ring_size = ri->cmpRingNumPages * PVSCSI_MAX_NUM_CMP_ENTRIES_PER_PAGE;
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txr_len_log2 = pvscsi_log2(req_ring_size - 1);
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@ -195,8 +191,6 @@ pvscsi_ring_init_data(PVSCSIRingInfo *m, PVSCSICmdDescSetupRings *ri)
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/* Flush ring state page changes */
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smp_wmb();
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return 0;
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}
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static int
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@ -746,7 +740,7 @@ pvscsi_dbg_dump_tx_rings_config(PVSCSICmdDescSetupRings *rc)
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trace_pvscsi_tx_rings_num_pages("Confirm Ring", rc->cmpRingNumPages);
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for (i = 0; i < rc->cmpRingNumPages; i++) {
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trace_pvscsi_tx_rings_ppn("Confirm Ring", rc->reqRingPPNs[i]);
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trace_pvscsi_tx_rings_ppn("Confirm Ring", rc->cmpRingPPNs[i]);
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}
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}
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@ -779,11 +773,16 @@ pvscsi_on_cmd_setup_rings(PVSCSIState *s)
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trace_pvscsi_on_cmd_arrived("PVSCSI_CMD_SETUP_RINGS");
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pvscsi_dbg_dump_tx_rings_config(rc);
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if (pvscsi_ring_init_data(&s->rings, rc) < 0) {
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if (!rc->reqRingNumPages
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|| rc->reqRingNumPages > PVSCSI_SETUP_RINGS_MAX_NUM_PAGES
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|| !rc->cmpRingNumPages
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|| rc->cmpRingNumPages > PVSCSI_SETUP_RINGS_MAX_NUM_PAGES) {
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return PVSCSI_COMMAND_PROCESSING_FAILED;
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}
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pvscsi_dbg_dump_tx_rings_config(rc);
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pvscsi_ring_init_data(&s->rings, rc);
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s->rings_info_valid = TRUE;
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return PVSCSI_COMMAND_PROCESSING_SUCCEEDED;
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}
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