From cf47a83fb06e42ae1b572ed68326068c7feaceae Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 19 Oct 2012 15:25:37 -0400 Subject: xen/hypercall: fix hypercall fallback code for very old hypervisors While copying the argument structures in HYPERVISOR_event_channel_op() and HYPERVISOR_physdev_op() into the local variable is sufficiently safe even if the actual structure is smaller than the container one, copying back eventual output values the same way isn't: This may collide with on-stack variables (particularly "rc") which may change between the first and second memcpy() (i.e. the second memcpy() could discard that change). Move the fallback code into out-of-line functions, and handle all of the operations known by this old a hypervisor individually: Some don't require copying back anything at all, and for the rest use the individual argument structures' sizes rather than the container's. Reported-by: Dan Carpenter Signed-off-by: Jan Beulich [v2: Reduce #define/#undef usage in HYPERVISOR_physdev_op_compat().] [v3: Fix compile errors when modules use said hypercalls] [v4: Add xen_ prefix to the HYPERCALL_..] [v5: Alter the name and only EXPORT_SYMBOL_GPL one of them] Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/fallback.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 80 insertions(+) create mode 100644 drivers/xen/fallback.c (limited to 'drivers/xen/fallback.c') diff --git a/drivers/xen/fallback.c b/drivers/xen/fallback.c new file mode 100644 index 000000000000..0ef7c4d40f86 --- /dev/null +++ b/drivers/xen/fallback.c @@ -0,0 +1,80 @@ +#include +#include +#include +#include +#include +#include + +int xen_event_channel_op_compat(int cmd, void *arg) +{ + struct evtchn_op op; + int rc; + + op.cmd = cmd; + memcpy(&op.u, arg, sizeof(op.u)); + rc = _hypercall1(int, event_channel_op_compat, &op); + + switch (cmd) { + case EVTCHNOP_close: + case EVTCHNOP_send: + case EVTCHNOP_bind_vcpu: + case EVTCHNOP_unmask: + /* no output */ + break; + +#define COPY_BACK(eop) \ + case EVTCHNOP_##eop: \ + memcpy(arg, &op.u.eop, sizeof(op.u.eop)); \ + break + + COPY_BACK(bind_interdomain); + COPY_BACK(bind_virq); + COPY_BACK(bind_pirq); + COPY_BACK(status); + COPY_BACK(alloc_unbound); + COPY_BACK(bind_ipi); +#undef COPY_BACK + + default: + WARN_ON(rc != -ENOSYS); + break; + } + + return rc; +} +EXPORT_SYMBOL_GPL(xen_event_channel_op_compat); + +int HYPERVISOR_physdev_op_compat(int cmd, void *arg) +{ + struct physdev_op op; + int rc; + + op.cmd = cmd; + memcpy(&op.u, arg, sizeof(op.u)); + rc = _hypercall1(int, physdev_op_compat, &op); + + switch (cmd) { + case PHYSDEVOP_IRQ_UNMASK_NOTIFY: + case PHYSDEVOP_set_iopl: + case PHYSDEVOP_set_iobitmap: + case PHYSDEVOP_apic_write: + /* no output */ + break; + +#define COPY_BACK(pop, fld) \ + case PHYSDEVOP_##pop: \ + memcpy(arg, &op.u.fld, sizeof(op.u.fld)); \ + break + + COPY_BACK(irq_status_query, irq_status_query); + COPY_BACK(apic_read, apic_op); + COPY_BACK(ASSIGN_VECTOR, irq_op); +#undef COPY_BACK + + default: + WARN_ON(rc != -ENOSYS); + break; + } + + return rc; +} -- cgit v1.2.3