[tboot-devel] Bug report: integer truncation in saved_misc_enable_msr

[Eric Li <lix...@gm...>]

I recently found that in tboot/include/txt/heap.h, os_mle_data_t
defines saved_misc_enable_msr with type uint32_t. However, MSRs
contain 64 bits, so uint64_t should be used. The consequence of this
bug is that in tboot/txt/txt.c, "os_mle_data->saved_misc_enable_msr =
rdmsr(MSR_IA32_MISC_ENABLE);" results in integer truncation.

On my machine (Dell 7050 with Intel(R) Core(TM) i5-7600 CPU @
3.50GHz), I see that IA32_MISC_ENABLE before SENTER is 0x4000840089.
However, IA32_MISC_ENABLE after SENTER is restored to 0x840089, where
the 34th bit is lost.

This bug appears in tboot-1.11.1, it also appears in the latest
version on sourceforge:
https://sourceforge.net/p/tboot/code/ci/20d511/tree/tboot/include/txt/heap.h#l288

Could you please fix this bug in tboot? Thank you.