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27 March 2024, 02:37:15 UTC
Revision 02a68d0503fa470abff8852e10b1890df5730a08 authored by Laurent Dufour on 02 September 2014, 16:13:01 UTC, committed by Paolo Bonzini on 03 September 2014, 08:34:07 UTC 
powerpc/kvm/cma: Fix panic introduces by signed shift operation
 
fc95ca7284bc54953165cba76c3228bd2cdb9591 introduces a memset in
kvmppc_alloc_hpt since the general CMA doesn't clear the memory it
allocates.

However, the size argument passed to memset is computed from a signed value
and its signed bit is extended by the cast the compiler is doing. This lead
to extremely large size value when dealing with order value >= 31, and
almost all the memory following the allocated space is cleaned. As a
consequence, the system is panicing and may even fail spawning the kdump
kernel.

This fix makes use of an unsigned value for the memset's size argument to
avoid sign extension. Among this fix, another shift operation which may
lead to signed extended value too is also fixed.

Cc: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 parent eebbcf6
History
Tip revision: 02a68d0503fa470abff8852e10b1890df5730a08 authored by Laurent Dufour on 02 September 2014, 16:13:01 UTC
powerpc/kvm/cma: Fix panic introduces by signed shift operation
Tip revision: 02a68d0
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