From 8dcc1d34661d58a7889fb06517c8738d1412d1bc Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Thu, 6 Aug 2020 23:24:57 -0700 Subject: [PATCH] kasan: don't tag stacks allocated with pagealloc Patch series "kasan: support stack instrumentation for tag-based mode", v2. This patch (of 5): Prepare Software Tag-Based KASAN for stack tagging support. With Tag-Based KASAN when kernel stacks are allocated via pagealloc (which happens when CONFIG_VMAP_STACK is not enabled), they get tagged. KASAN instrumentation doesn't expect the sp register to be tagged, and this leads to false-positive reports. Fix by resetting the tag of kernel stack pointers after allocation. Signed-off-by: Andrey Konovalov Signed-off-by: Andrew Morton Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Marco Elver Cc: Walter Wu Cc: Elena Petrova Cc: Vincenzo Frascino Cc: Catalin Marinas Cc: Ard Biesheuvel Link: http://lkml.kernel.org/r/cover.1596199677.git.andreyknvl@google.com Link: http://lkml.kernel.org/r/cover.1596544734.git.andreyknvl@google.com Link: http://lkml.kernel.org/r/12d8c678869268dd0884b01271ab592f30792abf.1596544734.git.andreyknvl@google.com Link: http://lkml.kernel.org/r/01c678b877755bcf29009176592402cdf6f2cb15.1596199677.git.andreyknvl@google.com Link: https://bugzilla.kernel.org/show_bug.cgi?id=203497 Signed-off-by: Linus Torvalds --- kernel/fork.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/fork.c b/kernel/fork.c index c7b4ce9d2647..35e9894d394c 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -261,7 +261,7 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node) THREAD_SIZE_ORDER); if (likely(page)) { - tsk->stack = page_address(page); + tsk->stack = kasan_reset_tag(page_address(page)); return tsk->stack; } return NULL; @@ -302,6 +302,7 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, { unsigned long *stack; stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node); + stack = kasan_reset_tag(stack); tsk->stack = stack; return stack; }