From: Prasad J Pandit Date: Wed, 14 Sep 2016 15:09:12 +0530 Subject: [PATCH] scsi: pvscsi: limit process IO loop to ring size 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 Signed-off-by: Prasad J Pandit Message-Id: <1473845952-30785-1-git-send-email-ppandit@redhat.com> Signed-off-by: Paolo Bonzini (cherry picked from commit d251157ac1928191af851d199a9ff255d330bec9) --- hw/scsi/vmw_pvscsi.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/hw/scsi/vmw_pvscsi.c b/hw/scsi/vmw_pvscsi.c index babac5a..a5ce7de 100644 --- a/hw/scsi/vmw_pvscsi.c +++ b/hw/scsi/vmw_pvscsi.c @@ -247,8 +247,11 @@ 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 =