[PATCH v3 1/1] NFSD: fix use-after-free in __nfs42_ssc_open()

[PATCH v3 1/1] NFSD: fix use-after-free in __nfs42_ssc_open()

[Dai Ngo]

Problem caused by source's vfsmount being unmounted but remains
on the delayed unmount list. This happens when nfs42_ssc_open()
return errors.

Fixed by removing nfsd4_interssc_connect(), leave the vfsmount
for the laundromat to unmount when idle time expires.

We don't need to call nfs_do_sb_deactive when nfs42_ssc_open
return errors since the file was not opened so nfs_server->active
was not incremented. Same as in nfsd4_copy, if we fail to
launch nfsd4_do_async_copy thread then there's no need to
call nfs_do_sb_deactive

Reported-by: Xingyuan Mo <hdthky0@gmail.com>
Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4proc.c | 20 +++++---------------
 1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 8beb2bc4c328..b79ee65ae016 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1463,13 +1463,6 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
 	return status;
 }
 
-static void
-nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
-{
-	nfs_do_sb_deactive(ss_mnt->mnt_sb);
-	mntput(ss_mnt);
-}
-
 /*
  * Verify COPY destination stateid.
  *
@@ -1572,11 +1565,6 @@ nfsd4_cleanup_inter_ssc(struct vfsmount *ss_mnt, struct file *filp,
 {
 }
 
-static void
-nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
-{
-}
-
 static struct file *nfs42_ssc_open(struct vfsmount *ss_mnt,
 				   struct nfs_fh *src_fh,
 				   nfs4_stateid *stateid)
@@ -1771,7 +1759,7 @@ static int nfsd4_do_async_copy(void *data)
 			default:
 				nfserr = nfserr_offload_denied;
 			}
-			nfsd4_interssc_disconnect(copy->ss_mnt);
+			/* ss_mnt will be unmounted by the laundromat */
 			goto do_callback;
 		}
 		nfserr = nfsd4_do_copy(copy, filp, copy->nf_dst->nf_file,
@@ -1852,8 +1840,10 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	if (async_copy)
 		cleanup_async_copy(async_copy);
 	status = nfserrno(-ENOMEM);
-	if (nfsd4_ssc_is_inter(copy))
-		nfsd4_interssc_disconnect(copy->ss_mnt);
+	/*
+	 * source's vfsmount of inter-copy will be unmounted
+	 * by the laundromat
+	 */
 	goto out;
 }
 
-- 
2.9.5

Re: [PATCH v3 1/1] NFSD: fix use-after-free in __nfs42_ssc_open()

[Xingyuan Mo]

On Tue, Dec 13, 2022 at 6:50 AM Dai Ngo <dai.ngo@oracle.com> wrote:
>
> Problem caused by source's vfsmount being unmounted but remains
> on the delayed unmount list. This happens when nfs42_ssc_open()
> return errors.
>
> Fixed by removing nfsd4_interssc_connect(), leave the vfsmount
> for the laundromat to unmount when idle time expires.
>
> We don't need to call nfs_do_sb_deactive when nfs42_ssc_open
> return errors since the file was not opened so nfs_server->active
> was not incremented. Same as in nfsd4_copy, if we fail to
> launch nfsd4_do_async_copy thread then there's no need to
> call nfs_do_sb_deactive
>
> Reported-by: Xingyuan Mo <hdthky0@gmail.com>
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
>  fs/nfsd/nfs4proc.c | 20 +++++---------------
>  1 file changed, 5 insertions(+), 15 deletions(-)
>
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 8beb2bc4c328..b79ee65ae016 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -1463,13 +1463,6 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
>         return status;
>  }
>
> -static void
> -nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
> -{
> -       nfs_do_sb_deactive(ss_mnt->mnt_sb);
> -       mntput(ss_mnt);
> -}
> -
>  /*
>   * Verify COPY destination stateid.
>   *
> @@ -1572,11 +1565,6 @@ nfsd4_cleanup_inter_ssc(struct vfsmount *ss_mnt, struct file *filp,
>  {
>  }
>
> -static void
> -nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
> -{
> -}
> -
>  static struct file *nfs42_ssc_open(struct vfsmount *ss_mnt,
>                                    struct nfs_fh *src_fh,
>                                    nfs4_stateid *stateid)
> @@ -1771,7 +1759,7 @@ static int nfsd4_do_async_copy(void *data)
>                         default:
>                                 nfserr = nfserr_offload_denied;
>                         }
> -                       nfsd4_interssc_disconnect(copy->ss_mnt);
> +                       /* ss_mnt will be unmounted by the laundromat */
>                         goto do_callback;
>                 }
>                 nfserr = nfsd4_do_copy(copy, filp, copy->nf_dst->nf_file,
> @@ -1852,8 +1840,10 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>         if (async_copy)
>                 cleanup_async_copy(async_copy);
>         status = nfserrno(-ENOMEM);
> -       if (nfsd4_ssc_is_inter(copy))
> -               nfsd4_interssc_disconnect(copy->ss_mnt);
> +       /*
> +        * source's vfsmount of inter-copy will be unmounted
> +        * by the laundromat
> +        */
>         goto out;
>  }
>
> --
> 2.9.5
>

My test results show that this patch can fix the problem.

Regards,
Xingyuan Mo

Re: [PATCH v3 1/1] NFSD: fix use-after-free in __nfs42_ssc_open()

[Greg KH]

On Mon, Dec 12, 2022 at 02:50:11PM -0800, Dai Ngo wrote:
> Problem caused by source's vfsmount being unmounted but remains
> on the delayed unmount list. This happens when nfs42_ssc_open()
> return errors.
> 
> Fixed by removing nfsd4_interssc_connect(), leave the vfsmount
> for the laundromat to unmount when idle time expires.
> 
> We don't need to call nfs_do_sb_deactive when nfs42_ssc_open
> return errors since the file was not opened so nfs_server->active
> was not incremented. Same as in nfsd4_copy, if we fail to
> launch nfsd4_do_async_copy thread then there's no need to
> call nfs_do_sb_deactive
> 
> Reported-by: Xingyuan Mo <hdthky0@gmail.com>
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
>  fs/nfsd/nfs4proc.c | 20 +++++---------------
>  1 file changed, 5 insertions(+), 15 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 8beb2bc4c328..b79ee65ae016 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -1463,13 +1463,6 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
>  	return status;
>  }
>  
> -static void
> -nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
> -{
> -	nfs_do_sb_deactive(ss_mnt->mnt_sb);
> -	mntput(ss_mnt);
> -}
> -
>  /*
>   * Verify COPY destination stateid.
>   *
> @@ -1572,11 +1565,6 @@ nfsd4_cleanup_inter_ssc(struct vfsmount *ss_mnt, struct file *filp,
>  {
>  }
>  
> -static void
> -nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
> -{
> -}
> -
>  static struct file *nfs42_ssc_open(struct vfsmount *ss_mnt,
>  				   struct nfs_fh *src_fh,
>  				   nfs4_stateid *stateid)
> @@ -1771,7 +1759,7 @@ static int nfsd4_do_async_copy(void *data)
>  			default:
>  				nfserr = nfserr_offload_denied;
>  			}
> -			nfsd4_interssc_disconnect(copy->ss_mnt);
> +			/* ss_mnt will be unmounted by the laundromat */
>  			goto do_callback;
>  		}
>  		nfserr = nfsd4_do_copy(copy, filp, copy->nf_dst->nf_file,
> @@ -1852,8 +1840,10 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  	if (async_copy)
>  		cleanup_async_copy(async_copy);
>  	status = nfserrno(-ENOMEM);
> -	if (nfsd4_ssc_is_inter(copy))
> -		nfsd4_interssc_disconnect(copy->ss_mnt);
> +	/*
> +	 * source's vfsmount of inter-copy will be unmounted
> +	 * by the laundromat
> +	 */
>  	goto out;
>  }
>  
> -- 
> 2.9.5
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- This looks like a new version of a previously submitted patch, but you
  did not list below the --- line any changes from the previous version.
  Please read the section entitled "The canonical patch format" in the
  kernel file, Documentation/SubmittingPatches for what needs to be done
  here to properly describe this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot

Re: [PATCH v3 1/1] NFSD: fix use-after-free in __nfs42_ssc_open()

[dai.ngo]

On 12/12/22 7:38 PM, Xingyuan Mo wrote:
> On Tue, Dec 13, 2022 at 6:50 AM Dai Ngo <dai.ngo@oracle.com> wrote:
>> Problem caused by source's vfsmount being unmounted but remains
>> on the delayed unmount list. This happens when nfs42_ssc_open()
>> return errors.
>>
>> Fixed by removing nfsd4_interssc_connect(), leave the vfsmount
>> for the laundromat to unmount when idle time expires.
>>
>> We don't need to call nfs_do_sb_deactive when nfs42_ssc_open
>> return errors since the file was not opened so nfs_server->active
>> was not incremented. Same as in nfsd4_copy, if we fail to
>> launch nfsd4_do_async_copy thread then there's no need to
>> call nfs_do_sb_deactive
>>
>> Reported-by: Xingyuan Mo <hdthky0@gmail.com>
>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>> ---
>>   fs/nfsd/nfs4proc.c | 20 +++++---------------
>>   1 file changed, 5 insertions(+), 15 deletions(-)
>>
>> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
>> index 8beb2bc4c328..b79ee65ae016 100644
>> --- a/fs/nfsd/nfs4proc.c
>> +++ b/fs/nfsd/nfs4proc.c
>> @@ -1463,13 +1463,6 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
>>          return status;
>>   }
>>
>> -static void
>> -nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
>> -{
>> -       nfs_do_sb_deactive(ss_mnt->mnt_sb);
>> -       mntput(ss_mnt);
>> -}
>> -
>>   /*
>>    * Verify COPY destination stateid.
>>    *
>> @@ -1572,11 +1565,6 @@ nfsd4_cleanup_inter_ssc(struct vfsmount *ss_mnt, struct file *filp,
>>   {
>>   }
>>
>> -static void
>> -nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
>> -{
>> -}
>> -
>>   static struct file *nfs42_ssc_open(struct vfsmount *ss_mnt,
>>                                     struct nfs_fh *src_fh,
>>                                     nfs4_stateid *stateid)
>> @@ -1771,7 +1759,7 @@ static int nfsd4_do_async_copy(void *data)
>>                          default:
>>                                  nfserr = nfserr_offload_denied;
>>                          }
>> -                       nfsd4_interssc_disconnect(copy->ss_mnt);
>> +                       /* ss_mnt will be unmounted by the laundromat */
>>                          goto do_callback;
>>                  }
>>                  nfserr = nfsd4_do_copy(copy, filp, copy->nf_dst->nf_file,
>> @@ -1852,8 +1840,10 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>>          if (async_copy)
>>                  cleanup_async_copy(async_copy);
>>          status = nfserrno(-ENOMEM);
>> -       if (nfsd4_ssc_is_inter(copy))
>> -               nfsd4_interssc_disconnect(copy->ss_mnt);
>> +       /*
>> +        * source's vfsmount of inter-copy will be unmounted
>> +        * by the laundromat
>> +        */
>>          goto out;
>>   }
>>
>> --
>> 2.9.5
>>
> My test results show that this patch can fix the problem.

Thank you Xingyuan for testing the patch.

-Dai

>
> Regards,
> Xingyuan Mo

Re: [PATCH v3 1/1] NFSD: fix use-after-free in __nfs42_ssc_open()

[Chuck Lever III]

> On Dec 12, 2022, at 10:38 PM, Xingyuan Mo <hdthky0@gmail.com> wrote:
> 
> On Tue, Dec 13, 2022 at 6:50 AM Dai Ngo <dai.ngo@oracle.com> wrote:
>> 
>> Problem caused by source's vfsmount being unmounted but remains
>> on the delayed unmount list. This happens when nfs42_ssc_open()
>> return errors.
>> 
>> Fixed by removing nfsd4_interssc_connect(), leave the vfsmount
>> for the laundromat to unmount when idle time expires.
>> 
>> We don't need to call nfs_do_sb_deactive when nfs42_ssc_open
>> return errors since the file was not opened so nfs_server->active
>> was not incremented. Same as in nfsd4_copy, if we fail to
>> launch nfsd4_do_async_copy thread then there's no need to
>> call nfs_do_sb_deactive
>> 
>> Reported-by: Xingyuan Mo <hdthky0@gmail.com>
>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>> ---
>> fs/nfsd/nfs4proc.c | 20 +++++---------------
>> 1 file changed, 5 insertions(+), 15 deletions(-)
>> 
>> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
>> index 8beb2bc4c328..b79ee65ae016 100644
>> --- a/fs/nfsd/nfs4proc.c
>> +++ b/fs/nfsd/nfs4proc.c
>> @@ -1463,13 +1463,6 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
>>        return status;
>> }
>> 
>> -static void
>> -nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
>> -{
>> -       nfs_do_sb_deactive(ss_mnt->mnt_sb);
>> -       mntput(ss_mnt);
>> -}
>> -
>> /*
>>  * Verify COPY destination stateid.
>>  *
>> @@ -1572,11 +1565,6 @@ nfsd4_cleanup_inter_ssc(struct vfsmount *ss_mnt, struct file *filp,
>> {
>> }
>> 
>> -static void
>> -nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
>> -{
>> -}
>> -
>> static struct file *nfs42_ssc_open(struct vfsmount *ss_mnt,
>>                                   struct nfs_fh *src_fh,
>>                                   nfs4_stateid *stateid)
>> @@ -1771,7 +1759,7 @@ static int nfsd4_do_async_copy(void *data)
>>                        default:
>>                                nfserr = nfserr_offload_denied;
>>                        }
>> -                       nfsd4_interssc_disconnect(copy->ss_mnt);
>> +                       /* ss_mnt will be unmounted by the laundromat */
>>                        goto do_callback;
>>                }
>>                nfserr = nfsd4_do_copy(copy, filp, copy->nf_dst->nf_file,
>> @@ -1852,8 +1840,10 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>>        if (async_copy)
>>                cleanup_async_copy(async_copy);
>>        status = nfserrno(-ENOMEM);
>> -       if (nfsd4_ssc_is_inter(copy))
>> -               nfsd4_interssc_disconnect(copy->ss_mnt);
>> +       /*
>> +        * source's vfsmount of inter-copy will be unmounted
>> +        * by the laundromat
>> +        */
>>        goto out;
>> }
>> 
>> --
>> 2.9.5
>> 
> 
> My test results show that this patch can fix the problem.

May I add "Tested-by: Xingyuan Mo <hdthky0@gmail.com>" to Dai's patch ?


--
Chuck Lever

Re: [PATCH v3 1/1] NFSD: fix use-after-free in __nfs42_ssc_open()

[Chuck Lever III]

> On Dec 12, 2022, at 5:50 PM, Dai Ngo <dai.ngo@oracle.com> wrote:
> 
> Problem caused by source's vfsmount being unmounted but remains
> on the delayed unmount list. This happens when nfs42_ssc_open()
> return errors.
> 
> Fixed by removing nfsd4_interssc_connect(), leave the vfsmount
> for the laundromat to unmount when idle time expires.
> 
> We don't need to call nfs_do_sb_deactive when nfs42_ssc_open
> return errors since the file was not opened so nfs_server->active
> was not incremented. Same as in nfsd4_copy, if we fail to
> launch nfsd4_do_async_copy thread then there's no need to
> call nfs_do_sb_deactive
> 
> Reported-by: Xingyuan Mo <hdthky0@gmail.com>
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>

LGTM. Thanks for your quick response!

I'll wait for review comments before applying.


> ---
> fs/nfsd/nfs4proc.c | 20 +++++---------------
> 1 file changed, 5 insertions(+), 15 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 8beb2bc4c328..b79ee65ae016 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -1463,13 +1463,6 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
> 	return status;
> }
> 
> -static void
> -nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
> -{
> -	nfs_do_sb_deactive(ss_mnt->mnt_sb);
> -	mntput(ss_mnt);
> -}
> -
> /*
>  * Verify COPY destination stateid.
>  *
> @@ -1572,11 +1565,6 @@ nfsd4_cleanup_inter_ssc(struct vfsmount *ss_mnt, struct file *filp,
> {
> }
> 
> -static void
> -nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
> -{
> -}
> -
> static struct file *nfs42_ssc_open(struct vfsmount *ss_mnt,
> 				   struct nfs_fh *src_fh,
> 				   nfs4_stateid *stateid)
> @@ -1771,7 +1759,7 @@ static int nfsd4_do_async_copy(void *data)
> 			default:
> 				nfserr = nfserr_offload_denied;
> 			}
> -			nfsd4_interssc_disconnect(copy->ss_mnt);
> +			/* ss_mnt will be unmounted by the laundromat */
> 			goto do_callback;
> 		}
> 		nfserr = nfsd4_do_copy(copy, filp, copy->nf_dst->nf_file,
> @@ -1852,8 +1840,10 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> 	if (async_copy)
> 		cleanup_async_copy(async_copy);
> 	status = nfserrno(-ENOMEM);
> -	if (nfsd4_ssc_is_inter(copy))
> -		nfsd4_interssc_disconnect(copy->ss_mnt);
> +	/*
> +	 * source's vfsmount of inter-copy will be unmounted
> +	 * by the laundromat
> +	 */
> 	goto out;
> }
> 
> -- 
> 2.9.5
> 

--
Chuck Lever

Re: [PATCH v3 1/1] NFSD: fix use-after-free in __nfs42_ssc_open()

[Xingyuan Mo]

On Tue, Dec 13, 2022 at 10:02 PM Chuck Lever III <chuck.lever@oracle.com> wrote:
> May I add "Tested-by: Xingyuan Mo <hdthky0@gmail.com>" to Dai's patch ?

Sure.

Regards,
Xingyuan Mo