efi/efi_test: Prevent an Oops in efi_runtime_query_capsulecaps()

efi/efi_test: Prevent an Oops in efi_runtime_query_capsulecaps()

If "qcaps.capsule_count" is ULONG_MAX then "qcaps.capsule_count + 1"
will overflow to zero and kcalloc() will return the ZERO_SIZE_PTR.  We
try to dereference it inside the loop and crash.

Signed-off-by: Dan Carpenter <[email protected]>
Signed-off-by: Matt Fleming <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
Acked-by: Ivan Hu <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Fixes: ff6301dabc3c ("efi: Add efi_test driver for exporting UEFI runtime service interfaces")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>