[coreboot-gerrit] Change in coreboot[master]: cpu/x86/smm: Add overflow check

[Nico Huber (Code Review)]

Hello Kyösti Mälkki, Aaron Durbin, Arthur Heymans, [e-mail],

I'd like you to do a code review. Please visit

https://review.coreboot.org/c/coreboot/+/38763

to review the following change.

Change subject: cpu/x86/smm: Add overflow check
......................................................................

cpu/x86/smm: Add overflow check

Rather bail out than run into undefined behavior.

Change-Id: Ife26a0abed0ce6bcafe1e7cd8f499618631c4df4
Signed-off-by: Nico Huber 
---
M src/cpu/x86/smm/smm_module_loader.c
1 file changed, 2 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/63/38763/1

diff --git a/src/cpu/x86/smm/smm_module_loader.c b/src/cpu/x86/smm/smm_module_loader.c
index a421436..81020a4 100644
--- a/src/cpu/x86/smm/smm_module_loader.c
+++ b/src/cpu/x86/smm/smm_module_loader.c
@@ -202,6 +202,8 @@
    /* Adjust remaining size to account for save state. */
    total_save_state_size = params->per_cpu_save_state_size *
    			params->num_concurrent_save_states;
+	if (total_save_state_size > size)
+		return -1;
    size -= total_save_state_size;

/* The save state size encroached over the first SMM entry point. */