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Blame 0001-vmw_pvscsi-check-page-count-while-initialising-descr.patch

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From: Prasad J Pandit <pjp@fedoraproject.org>
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Date: Wed, 31 Aug 2016 12:19:29 +0530
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Subject: [PATCH] vmw_pvscsi: check page count while initialising descriptor
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 rings
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Vmware Paravirtual SCSI emulation uses command descriptors to
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process SCSI commands. These descriptors come with their ring
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buffers. A guest could set the page count for these rings to
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an arbitrary value, leading to infinite loop or OOB access.
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Add check to avoid it.
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Reported-by: Tom Victor <vv474172261@gmail.com>
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Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
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Message-Id: <1472626169-12989-1-git-send-email-ppandit@redhat.com>
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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(cherry picked from commit 7f61f4690dd153be98900a2a508b88989e692753)
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---
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 hw/scsi/vmw_pvscsi.c | 19 +++++++++----------
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 1 file changed, 9 insertions(+), 10 deletions(-)
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diff --git a/hw/scsi/vmw_pvscsi.c b/hw/scsi/vmw_pvscsi.c
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index 5116f4a..4245c15 100644
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--- a/hw/scsi/vmw_pvscsi.c
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+++ b/hw/scsi/vmw_pvscsi.c
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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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-
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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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+
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     s->rings_info_valid = TRUE;
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     return PVSCSI_COMMAND_PROCESSING_SUCCEEDED;
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 }