[Minios-devel] [UNIKRAFT PATCH 3/3] plat/kvm: Fix overwriting on stack for arm64

[Jia He <justin.he@xxxxxxx>]

On arm64, the _libkvmplat_cfg.bstack.end is the memory upper boundary.
Any overflow writing beyond this will cause an exception.

Fix it by writing the thread inside the boundary.
Signed-off-by: Jia He <justin.he@xxxxxxx>
---
 plat/kvm/memory.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/plat/kvm/memory.c b/plat/kvm/memory.c
index e96bad2..d84eaed 100644
--- a/plat/kvm/memory.c
+++ b/plat/kvm/memory.c
@@ -181,6 +181,7 @@ int _ukplat_mem_mappings_init(void)
 
 void ukplat_stack_set_current_thread(void *thread_addr)
 {
-       *((unsigned long *) _libkvmplat_cfg.bstack.end) =
+       unsigned long size = sizeof(thread_addr);
+       *((unsigned long *) _libkvmplat_cfg.bstack.end - size) =
                (unsigned long) thread_addr;
 }
-- 
2.17.1


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