[coreboot-gerrit] Change in coreboot[master]: cpu/x86: Put guard around align for smm_save_state_size

[Nico Huber (Code Review)]

Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/38734 )

Change subject: cpu/x86: Put guard around align for smm_save_state_size
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Patch Set 3:

(2 comments)

https://review.coreboot.org/c/coreboot/+/38734/3/src/cpu/x86/mp_init.c 
File src/cpu/x86/mp_init.c:

PS3: 
So is this an Intel-only tech? If so, the changes to this file should be
moved to the .get_smm_info and .relocation_handler callbacks.

https://review.coreboot.org/c/coreboot/+/38734/3/src/cpu/x86/mp_init.c@1056 
PS3, Line 1056: 		 * value of 0x400 for this value.
> Patrick Rudolph noted in a previous comment:  "It looks like coreboot assumes 0x400 as safe value fo […]

You have to be careful what code you read. smmhandler.S, smmhandler.c,
smmrelocate.S are for non-TSEG (very old) platforms. For TSEG platforms,
focus on mp_init.c, and smm/smm_*.

I don't think it's the alignment that breaks things, it's the absolute size.
Have a look at smm_module_setup_stub(). It uses SMM_DEFAULT_SIZE. I guess
that should be made a parameter. I would start by adding an overflow check
before line 205.