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vfio: ccw: fix bad ptr math for TIC cda translation

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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@linux.vnet.ibm.com>
Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Message-Id: <20170721011436.76112-1-bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
This commit is contained in:
Jason J. Herne 2017-07-21 03:14:36 +02:00 committed by Cornelia Huck
parent 97ca7bfc19
commit c389377c01
1 changed files with 1 additions and 1 deletions
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2
drivers/s390/cio/vfio_ccw_cp.c
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@ -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;
}