Thanks for your review.
I will send v2 patch to update the commit description and resolve the
conflicts in your for-next branch
在 2022/5/21 0:05, Bruce Fields 写道:
On Fri, May 20, 2022 at 03:22:51PM +0000, Chuck Lever III wrote:
[ Note well: Updated Bruce's email address. ]
On May 19, 2022, at 10:31 PM, Zhang Xiaoxu <zhangxiaoxu5@xxxxxxxxxx> wrote:
KASAN report null-ptr-deref as follows:
BUG: KASAN: null-ptr-deref in nfsd_fill_super+0xc6/0xe0 [nfsd]
Write of size 8 at addr 000000000000005d by task a.out/852
CPU: 7 PID: 852 Comm: a.out Not tainted 5.18.0-rc7-dirty #66
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x34/0x44
kasan_report+0xab/0x120
? nfsd_mkdir+0x71/0x1c0 [nfsd]
? nfsd_fill_super+0xc6/0xe0 [nfsd]
nfsd_fill_super+0xc6/0xe0 [nfsd]
? nfsd_mkdir+0x1c0/0x1c0 [nfsd]
get_tree_keyed+0x8e/0x100
vfs_get_tree+0x41/0xf0
__do_sys_fsconfig+0x590/0x670
? fscontext_read+0x180/0x180
? anon_inode_getfd+0x4f/0x70
do_syscall_64+0x35/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
This can be reproduce by concurrent operations:
1. fsopen(nfsd)/fsconfig
2. insmod/rmmod nfsd
Since the nfsd file system is registered before than nfsd_net allocated,
the caller may get the file_system_type and use the nfsd_net before it
allocated, then null-ptr-deref occured.
So should allocate the nfsd_net firstly, other than register file system.
IIUC, I suggest: "So init_nfsd() should call register_filesystem() last."
Fixes: bd5ae9288d64 ("nfsd: register pernet ops last, unregister first")
Cc: stable@xxxxxxxxxx
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@xxxxxxxxxx>
I think this looks right. Bruce, as author of bd5ae9288d64, any
thoughts?
I'm not seeing any problem with the patch.
Reviewed-by: J. Bruce Fields <bfields@xxxxxxxxxxxx>
--b.
I need a v2 of this, though. The current version conflicts with the
courteous server patches already in my for-next branch. See:
https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git/log/?h=for-next
---
fs/nfsd/nfsctl.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 16920e4512bd..e17100e90e19 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1535,20 +1535,20 @@ static int __init init_nfsd(void)
retval = create_proc_exports_entry();
if (retval)
goto out_free_lockd;
- retval = register_filesystem(&nfsd_fs_type);
- if (retval)
- goto out_free_exports;
retval = register_pernet_subsys(&nfsd_net_ops);
if (retval < 0)
- goto out_free_filesystem;
+ goto out_free_exports;
retval = register_cld_notifier();
+ if (retval)
+ goto out_free_subsys;
+ retval = register_filesystem(&nfsd_fs_type);
if (retval)
goto out_free_all;
return 0;
out_free_all:
+ unregister_cld_notifier();
+out_free_subsys:
unregister_pernet_subsys(&nfsd_net_ops);
-out_free_filesystem:
- unregister_filesystem(&nfsd_fs_type);
out_free_exports:
remove_proc_entry("fs/nfs/exports", NULL);
remove_proc_entry("fs/nfs", NULL);
@@ -1566,6 +1566,7 @@ static int __init init_nfsd(void)
static void __exit exit_nfsd(void)
{
+ unregister_filesystem(&nfsd_fs_type);
unregister_cld_notifier();
unregister_pernet_subsys(&nfsd_net_ops);
nfsd_drc_slab_free();
@@ -1575,7 +1576,6 @@ static void __exit exit_nfsd(void)
nfsd_lockd_shutdown();
nfsd4_free_slabs();
nfsd4_exit_pnfs();
- unregister_filesystem(&nfsd_fs_type);
}
MODULE_AUTHOR("Olaf Kirch <okir@xxxxxxxxxxxx>");
--
2.31.1
--
Chuck Lever
.
