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List: linux-arm-kernel
Subject: [PATCH 21/31] kasan, fork: don't tag stacks allocated with vmalloc
From: andrey.konovalov () linux ! dev
Date: 2021-11-30 22:07:06
Message-ID: 4fbc6668845e699bf708aee5c11ad9fd012d4dcd.1638308023.git.andreyknvl () google ! com
[Download RAW message or body]
From: Andrey Konovalov <andreyknvl@google.com>
Once tag-based KASAN modes start tagging vmalloc() allocations,
kernel stacks will start getting tagged if CONFIG_VMAP_STACK is enabled.
Reset the tag of kernel stack pointers after allocation.
For SW_TAGS KASAN, when CONFIG_KASAN_STACK is enabled, the
instrumentation can't handle the sp register being tagged.
For HW_TAGS KASAN, there's no instrumentation-related issues. However,
the impact of having a tagged SP pointer needs to be properly evaluated,
so keep it non-tagged for now.
Note, that the memory for the stack allocation still gets tagged to
catch vmalloc-into-stack out-of-bounds accesses.
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
kernel/fork.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/fork.c b/kernel/fork.c
index 3244cc56b697..062d1484ef42 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -253,6 +253,7 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
* so cache the vm_struct.
*/
if (stack) {
+ stack = kasan_reset_tag(stack);
tsk->stack_vm_area = find_vm_area(stack);
tsk->stack = stack;
}
--
2.25.1
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