From: "Jason J. Herne" <jjherne@xxxxxxxxxxxxxxxxxx>
When we are translating channel data addresses from guest to host
address space for TIC instructions we are getting incorrect
addresses because of a pointer arithmetic error.
We currently calculate the offset of the TIC's cda from the start
of the channel program chain (ccw->cda - ccw_head). We then add
that to the address of the ccw chain in host memory (iter->ch_ccw).
The problem is that iter->ch_ccw is a pointer to struct ccw1 so
when we increment it we are actually incrementing by the size of
struct ccw1 which is 8 bytes. The intent was to increment by
n-bytes, not n*8.
The fix: cast iter->ch_ccw to char* so it will be incremented by
n*1.
Reviewed-by: Dong Jia Shi <bjsdjshi@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jason J. Herne <jjherne@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Dong Jia Shi <bjsdjshi@xxxxxxxxxxxxxxxxxx>
Message-Id: <20170721011436.76112-1-bjsdjshi@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Cornelia Huck <cohuck@xxxxxxxxxx>
---
drivers/s390/cio/vfio_ccw_cp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index ba6ac83a6c25..5ccfdc80d0ec 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -481,7 +481,7 @@ static int ccwchain_fetch_tic(struct ccwchain *chain,
ccw_tail = ccw_head + (iter->ch_len - 1) * sizeof(struct ccw1);
if ((ccw_head <= ccw->cda) && (ccw->cda <= ccw_tail)) {
- ccw->cda = (__u32) (addr_t) (iter->ch_ccw +
+ ccw->cda = (__u32) (addr_t) (((char *)iter->ch_ccw) +
(ccw->cda - ccw_head));
return 0;
}
--
2.13.3
