> On Sep 30, 2021, at 10:16 AM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
>
> On Thu, Sep 30, 2021 at 03:48:42AM +0000, Ho, Patrick wrote:
>>> From 7417896fcc7aea645fa0b89f39fa55979251dca3 Mon Sep 17 00:00:00 2001
>> From: Patrick Ho <Patrick.Ho@xxxxxxxxxx>
>> Date: Sat, 21 Aug 2021 02:56:26 -0400
>> Subject: [PATCH] nfsd: fix error handling of register_pernet_subsys() in
>> init_nfsd()
>>
>> init_nfsd() should not unregister pernet subsys if the register fails
>> but should instead unwind from the last successful operation which is
>> register_filesystem().
>>
>> Unregistering a failed register_pernet_subsys() call can result in
>> a kernel GPF as revealed by programmatically injecting an error in
>> register_pernet_subsys().
>>
>> Verified the fix handled failure gracefully with no lingering nfsd
>> entry in /proc/filesystems. This change was introduced by the commit
>> bd5ae9288d64 ("nfsd: register pernet ops last, unregister first"),
>> the original error handling logic was correct.
>
> Whoops, thanks for catching this. I assume Chuck will pick it up.
Applied to the for-next branch at
git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git
> Acked-by: J. Bruce Fields <bfields@xxxxxxxxxx>
>
> --b.
>
>>
>> Fixes: bd5ae9288d64 ("nfsd: register pernet ops last, unregister first")
>> Cc: stable@xxxxxxxxxxxxxxx
>> Signed-off-by: Patrick Ho <Patrick.Ho@xxxxxxxxxx>
>> ---
>> fs/nfsd/nfsctl.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
>> index c2c3d9077dc5..09ae1a0873d0 100644
>> --- a/fs/nfsd/nfsctl.c
>> +++ b/fs/nfsd/nfsctl.c
>> @@ -1545,7 +1545,7 @@ static int __init init_nfsd(void)
>> goto out_free_all;
>> return 0;
>> out_free_all:
>> - unregister_pernet_subsys(&nfsd_net_ops);
>> + unregister_filesystem(&nfsd_fs_type);
>> out_free_exports:
>> remove_proc_entry("fs/nfs/exports", NULL);
>> remove_proc_entry("fs/nfs", NULL);
>> --
>> 2.17.1
--
Chuck Lever
