linux-kernel - [PATCH 1/4] kasan: don't tag stacks allocated with pagealloc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <01c678b877755bcf29009176592402cdf6f2cb15.1596199677.git.andreyknvl@google.com>
Date:   Fri, 31 Jul 2020 15:20:38 +0200
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Marco Elver <elver@...gle.com>, kasan-dev@...glegroups.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Walter Wu <walter-zh.wu@...iatek.com>,
        Elena Petrova <lenaptr@...gle.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH 1/4] kasan: don't tag stacks allocated with pagealloc

This patch prepares 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 <andreyknvl@...gle.com>
---
 kernel/fork.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index d03c9586d342..9cea2265e677 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;
 }
-- 
2.28.0.163.g6104cc2f0b6-goog