linux-kernel - [PATCH mm] fix for "kasan, fork: reset pointer tags of vmapped stacks"

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-next>] [day] [month] [year] [list]

Date:   Tue, 15 Feb 2022 17:52:17 +0100
From:   andrey.konovalov@...ux.dev
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Andrey Konovalov <andreyknvl@...il.com>,
        Marco Elver <elver@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH mm] fix for "kasan, fork: reset pointer tags of vmapped stacks"

From: Andrey Konovalov <andreyknvl@...gle.com>

That patch didn't update the case when a stack is retrived from
cached_stacks in alloc_thread_stack_node(). As cached_stacks stores
vm_structs and not stack pointers themselves, the pointer tag needs
to be reset there as well.

Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 kernel/fork.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 57d624f05182..5e3ad2e7a756 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -226,15 +226,17 @@ static unsigned long *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);
 
 		tsk->stack_vm_area = s;
-		tsk->stack = s->addr;
-		return s->addr;
+		tsk->stack = stack;
+		return stack;
 	}
 
 	/*
-- 
2.25.1