The BUG_ON() is confusing to follow. The (!is_idle_domain(d) || vcpu_id) part is a vestigial remnant of architectures poisioning idle_vcpu[0] with non-NULL pointers.
Now that idle_vcpu[0] is NULL on all architectures, and d->max_vcpus specified before vcpu_create() is called, we can properly range check the requested vcpu_id. Signed-off-by: Andrew Cooper <[email protected]> --- CC: Jan Beulich <[email protected]> CC: Wei Liu <[email protected]> CC: Roger Pau Monné <[email protected]> CC: Stefano Stabellini <[email protected]> CC: Julien Grall <[email protected]> CC: Volodymyr Babchuk <[email protected]> --- xen/common/domain.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/xen/common/domain.c b/xen/common/domain.c index 0b1103fdb2..ee3f9ffd3e 100644 --- a/xen/common/domain.c +++ b/xen/common/domain.c @@ -139,7 +139,19 @@ struct vcpu *vcpu_create(struct domain *d, unsigned int vcpu_id) { struct vcpu *v; - BUG_ON((!is_idle_domain(d) || vcpu_id) && d->vcpu[vcpu_id]); + /* + * Sanity check some input expectations: + * - vcpu_id should be bounded by d->max_vcpus, and not previously + * allocated. + * - VCPUs should be tightly packed and allocated in ascending order, + * except for the idle domain which may vary based on PCPU numbering. + */ + if ( vcpu_id >= d->max_vcpus || d->vcpu[vcpu_id] || + (!is_idle_domain(d) && vcpu_id && !d->vcpu[vcpu_id - 1]) ) + { + ASSERT_UNREACHABLE(); + return NULL; + } if ( (v = alloc_vcpu_struct(d)) == NULL ) return NULL; -- 2.11.0 _______________________________________________ Xen-devel mailing list [email protected] https://lists.xenproject.org/mailman/listinfo/xen-devel
