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[10/67] scsi: pvscsi: limit process IO loop to ring size

Message ID 1481762701-4587-11-git-send-email-mdroth@linux.vnet.ibm.com
State New
Headers show

Commit Message

Michael Roth Dec. 15, 2016, 12:44 a.m. UTC 
From: Prasad J Pandit <pjp@fedoraproject.org>

Vmware Paravirtual SCSI emulator while processing IO requests
could run into an infinite loop if 'pvscsi_ring_pop_req_descr'
always returned positive value. Limit IO loop to the ring size.

Cc: qemu-stable@nongnu.org
Reported-by: Li Qiang <liqiang6-s@360.cn>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-Id: <1473845952-30785-1-git-send-email-ppandit@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit d251157ac1928191af851d199a9ff255d330bec9)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 hw/scsi/vmw_pvscsi.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/hw/scsi/vmw_pvscsi.c b/hw/scsi/vmw_pvscsi.c
index 5116f4a..aaaae0a 100644
--- a/hw/scsi/vmw_pvscsi.c
+++ b/hw/scsi/vmw_pvscsi.c
@@ -251,8 +251,11 @@  static hwaddr
 pvscsi_ring_pop_req_descr(PVSCSIRingInfo *mgr)
 {
     uint32_t ready_ptr = RS_GET_FIELD(mgr, reqProdIdx);
+    uint32_t ring_size = PVSCSI_MAX_NUM_PAGES_REQ_RING
+                            * PVSCSI_MAX_NUM_REQ_ENTRIES_PER_PAGE;
 
-    if (ready_ptr != mgr->consumed_ptr) {
+    if (ready_ptr != mgr->consumed_ptr
+        && ready_ptr - mgr->consumed_ptr < ring_size) {
         uint32_t next_ready_ptr =
             mgr->consumed_ptr++ & mgr->txr_len_mask;
         uint32_t next_ready_page =