[merged] kasan-arm64-reset-pointer-tags-of-vmapped-stacks.patch removed from -mm tree

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The patch titled
     Subject: kasan, arm64: reset pointer tags of vmapped stacks
has been removed from the -mm tree.  Its filename was
     kasan-arm64-reset-pointer-tags-of-vmapped-stacks.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: kasan, arm64: reset pointer tags of vmapped stacks

Once tag-based KASAN modes start tagging vmalloc() allocations, kernel
stacks start getting tagged if CONFIG_VMAP_STACK is enabled.

Reset the tag of kernel stack pointers after allocation in
arch_alloc_vmap_stack().

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 register 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.

[andreyknvl@xxxxxxxxxx: fix case when a stack is retrieved from cached_stacks]
  Link: https://lkml.kernel.org/r/f50c5f96ef896d7936192c888b0c0a7674e33184.1644943792.git.andreyknvl@xxxxxxxxxx
[dan.carpenter@xxxxxxxxxx: remove unnecessary check in alloc_thread_stack_node()]
  Link: https://lkml.kernel.org/r/20220301080706.GB17208@kili
Link: https://lkml.kernel.org/r/698c5ab21743c796d46c15d075b9481825973e34.1643047180.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Acked-by: Marco Elver <elver@xxxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Peter Collingbourne <pcc@xxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 arch/arm64/include/asm/vmap_stack.h |    5 ++++-
 kernel/fork.c                       |   11 ++++++-----
 2 files changed, 10 insertions(+), 6 deletions(-)

--- a/arch/arm64/include/asm/vmap_stack.h~kasan-arm64-reset-pointer-tags-of-vmapped-stacks
+++ a/arch/arm64/include/asm/vmap_stack.h
@@ -17,10 +17,13 @@
  */
 static inline unsigned long *arch_alloc_vmap_stack(size_t stack_size, int node)
 {
+	void *p;
+
 	BUILD_BUG_ON(!IS_ENABLED(CONFIG_VMAP_STACK));
 
-	return __vmalloc_node(stack_size, THREAD_ALIGN, THREADINFO_GFP, node,
+	p = __vmalloc_node(stack_size, THREAD_ALIGN, THREADINFO_GFP, node,
 			__builtin_return_address(0));
+	return kasan_reset_tag(p);
 }
 
 #endif /* __ASM_VMAP_STACK_H */
--- a/kernel/fork.c~kasan-arm64-reset-pointer-tags-of-vmapped-stacks
+++ a/kernel/fork.c
@@ -286,11 +286,13 @@ static int alloc_thread_stack_node(struc
 		if (!s)
 			continue;
 
-		/* Mark stack accessible for KASAN. */
+		/* Reset stack metadata. */
 		kasan_unpoison_range(s->addr, THREAD_SIZE);
 
+		stack = kasan_reset_tag(s->addr);
+
 		/* Clear stale pointers from reused stack. */
-		memset(s->addr, 0, THREAD_SIZE);
+		memset(stack, 0, THREAD_SIZE);
 
 		if (memcg_charge_kernel_stack(s)) {
 			vfree(s->addr);
@@ -298,7 +300,7 @@ static int alloc_thread_stack_node(struc
 		}
 
 		tsk->stack_vm_area = s;
-		tsk->stack = s->addr;
+		tsk->stack = stack;
 		return 0;
 	}
 
@@ -326,8 +328,7 @@ static int alloc_thread_stack_node(struc
 	 * so cache the vm_struct.
 	 */
 	tsk->stack_vm_area = vm;
-	if (stack)
-		stack = kasan_reset_tag(stack);
+	stack = kasan_reset_tag(stack);
 	tsk->stack = stack;
 	return 0;
 }
_

Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are

stacktrace-add-interface-based-on-shadow-call-stack.patch
arm64-scs-save-scs_sp-values-per-cpu-when-switching-stacks.patch
arm64-implement-stack_trace_save_shadow.patch
kasan-use-stack_trace_save_shadow.patch




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