From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Thu, 20 Oct 2016 13:10:24 +0530
Subject: [PATCH] audio: intel-hda: check stream entry count during transfer

Intel HDA emulator uses stream of buffers during DMA data
transfers. Each entry has buffer length and buffer pointer
position, which are used to derive bytes to 'copy'. If this
length and buffer pointer were to be same, 'copy' could be
set to zero(0), leading to an infinite loop. Add check to
avoid it.

Reported-by: Huawei PSIRT <psirt@huawei.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1476949224-6865-1-git-send-email-ppandit@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit 0c0fc2b5fd534786051889459848764edd798050)
---
 hw/audio/intel-hda.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/audio/intel-hda.c b/hw/audio/intel-hda.c
index cd95340..537face 100644
--- a/hw/audio/intel-hda.c
+++ b/hw/audio/intel-hda.c
@@ -416,7 +416,8 @@ static bool intel_hda_xfer(HDACodecDevice *dev, uint32_t stnr, bool output,
     }
 
     left = len;
-    while (left > 0) {
+    s = st->bentries;
+    while (left > 0 && s-- > 0) {
         copy = left;
         if (copy > st->bsize - st->lpib)
             copy = st->bsize - st->lpib;