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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 <dan.carpenter@oracle.com> Signed-off-by: Jan Beulich <jbeulich@suse.com> [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 <konrad.wilk@oracle.com>
80 lines
1.5 KiB
C
80 lines
1.5 KiB
C
#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/bug.h>
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#include <linux/export.h>
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#include <asm/hypervisor.h>
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#include <asm/xen/hypercall.h>
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int xen_event_channel_op_compat(int cmd, void *arg)
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{
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struct evtchn_op op;
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int rc;
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op.cmd = cmd;
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memcpy(&op.u, arg, sizeof(op.u));
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rc = _hypercall1(int, event_channel_op_compat, &op);
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switch (cmd) {
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case EVTCHNOP_close:
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case EVTCHNOP_send:
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case EVTCHNOP_bind_vcpu:
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case EVTCHNOP_unmask:
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/* no output */
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break;
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#define COPY_BACK(eop) \
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case EVTCHNOP_##eop: \
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memcpy(arg, &op.u.eop, sizeof(op.u.eop)); \
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break
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COPY_BACK(bind_interdomain);
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COPY_BACK(bind_virq);
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COPY_BACK(bind_pirq);
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COPY_BACK(status);
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COPY_BACK(alloc_unbound);
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COPY_BACK(bind_ipi);
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#undef COPY_BACK
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default:
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WARN_ON(rc != -ENOSYS);
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break;
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}
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return rc;
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}
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EXPORT_SYMBOL_GPL(xen_event_channel_op_compat);
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int HYPERVISOR_physdev_op_compat(int cmd, void *arg)
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{
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struct physdev_op op;
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int rc;
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op.cmd = cmd;
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memcpy(&op.u, arg, sizeof(op.u));
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rc = _hypercall1(int, physdev_op_compat, &op);
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switch (cmd) {
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case PHYSDEVOP_IRQ_UNMASK_NOTIFY:
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case PHYSDEVOP_set_iopl:
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case PHYSDEVOP_set_iobitmap:
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case PHYSDEVOP_apic_write:
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/* no output */
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break;
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#define COPY_BACK(pop, fld) \
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case PHYSDEVOP_##pop: \
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memcpy(arg, &op.u.fld, sizeof(op.u.fld)); \
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break
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COPY_BACK(irq_status_query, irq_status_query);
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COPY_BACK(apic_read, apic_op);
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COPY_BACK(ASSIGN_VECTOR, irq_op);
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#undef COPY_BACK
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default:
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WARN_ON(rc != -ENOSYS);
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break;
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}
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return rc;
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}
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