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authorAndrey Konovalov <andreyknvl@google.com>2022-03-25 04:11:10 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-25 05:06:47 +0300
commit51fb34de2a4c8fa0f221246313700bfe3b6c586d (patch)
tree89638ec06e30cf01a3e502843f63e303b1b7a2b4
parentc08e6a1206e6876c66e0528b3ec717f557b07dd4 (diff)
downloadlinux-51fb34de2a4c8fa0f221246313700bfe3b6c586d.tar.xz
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@google.com: fix case when a stack is retrieved from cached_stacks] Link: https://lkml.kernel.org/r/f50c5f96ef896d7936192c888b0c0a7674e33184.1644943792.git.andreyknvl@google.com [dan.carpenter@oracle.com: 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@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Marco Elver <elver@google.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Collingbourne <pcc@google.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/arm64/include/asm/vmap_stack.h5
-rw-r--r--kernel/fork.c11
2 files changed, 10 insertions, 6 deletions
diff --git a/arch/arm64/include/asm/vmap_stack.h b/arch/arm64/include/asm/vmap_stack.h
index 894e031b28d2..20873099c035 100644
--- a/arch/arm64/include/asm/vmap_stack.h
+++ b/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 */
diff --git a/kernel/fork.c b/kernel/fork.c
index ce0ffe48937f..9796897560ab 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -286,11 +286,13 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node)
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(struct task_struct *tsk, int node)
}
tsk->stack_vm_area = s;
- tsk->stack = s->addr;
+ tsk->stack = stack;
return 0;
}
@@ -326,8 +328,7 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node)
* 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;
}