From c389377c01bf2d6e2a178e86aef8535931bfbd75 Mon Sep 17 00:00:00 2001 From: "Jason J. Herne" Date: Fri, 21 Jul 2017 03:14:36 +0200 Subject: [PATCH] vfio: ccw: fix bad ptr math for TIC cda translation 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 Signed-off-by: Jason J. Herne Signed-off-by: Dong Jia Shi Message-Id: <20170721011436.76112-1-bjsdjshi@linux.vnet.ibm.com> Signed-off-by: Cornelia Huck --- 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; }