linux-kernel - [PATCH] dax: make sure inodes are flushed before destroy cache

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:   Fri, 11 Feb 2022 23:11:11 -0800
From:   Tong Zhang <ztong0001@...il.com>
To:     Dan Williams <dan.j.williams@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>, nvdimm@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Cc:     Tong Zhang <ztong0001@...il.com>
Subject: [PATCH] dax: make sure inodes are flushed before destroy cache

A bug can be triggered by following command

$ modprobe nd_pmem && modprobe -r nd_pmem

[   10.060014] BUG dax_cache (Not tainted): Objects remaining in dax_cache on __kmem_cache_shutdown()
[   10.060938] Slab 0x0000000085b729ac objects=9 used=1 fp=0x000000004f5ae469 flags=0x200000000010200(slab|head|node)
[   10.062433] Call Trace:
[   10.062673]  dump_stack_lvl+0x34/0x44
[   10.062865]  slab_err+0x90/0xd0
[   10.063619]  __kmem_cache_shutdown+0x13b/0x2f0
[   10.063848]  kmem_cache_destroy+0x4a/0x110
[   10.064058]  __x64_sys_delete_module+0x265/0x300

This is caused by dax_fs_exit() not flushing inodes before destroy cache.
To fix this issue, call rcu_barrier() before destroy cache.

Signed-off-by: Tong Zhang <ztong0001@...il.com>
---
 drivers/dax/super.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index e3029389d809..6bd565fe2e63 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -476,6 +476,7 @@ static int dax_fs_init(void)
 static void dax_fs_exit(void)
 {
 	kern_unmount(dax_mnt);
+	rcu_barrier();
 	kmem_cache_destroy(dax_cache);
 }
 
-- 
2.25.1