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vmw_pvscsi: check page count while initialising descriptor rings

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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>
This commit is contained in:
Prasad J Pandit 2016-08-31 12:19:29 +05:30 committed by Paolo Bonzini
parent 48b6206305
commit 7f61f4690d
1 changed files with 9 additions and 10 deletions
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19
hw/scsi/vmw_pvscsi.c
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@ -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;
}