From: Norbert Manthey Date: Thu, 14 Mar 2019 12:56:00 +0000 (+0100) Subject: x86/hvm: add nospec to hvmop param X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=93dfd72bdb43b35dbb1424c476d17aac67e82837;p=people%2Fsstabellini%2Fxen-unstable.git%2F.git x86/hvm: add nospec to hvmop param The params array in hvm can be accessed with get and set functions. As the index is guest controlled, make sure no out-of-bound accesses can be performed. As we cannot influence how future compilers might modify the instructions that enforce the bounds, we furthermore block speculation, so that the update is visible in the architectural state. This is part of the speculative hardening effort. Signed-off-by: Norbert Manthey Acked-by: Jan Beulich --- diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c index 11ce21fc08..e798b49b66 100644 --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -4145,6 +4145,9 @@ static int hvmop_set_param( if ( a.index >= HVM_NR_PARAMS ) return -EINVAL; + /* Make sure the above bound check is not bypassed during speculation. */ + block_speculation(); + d = rcu_lock_domain_by_any_id(a.domid); if ( d == NULL ) return -ESRCH; @@ -4411,6 +4414,9 @@ static int hvmop_get_param( if ( a.index >= HVM_NR_PARAMS ) return -EINVAL; + /* Make sure the above bound check is not bypassed during speculation. */ + block_speculation(); + d = rcu_lock_domain_by_any_id(a.domid); if ( d == NULL ) return -ESRCH;