nfs: check nf pointer for validity before use

[PATCH] nfs: check nf pointer for validity before use

Posted by Muhammad Usama Anjum 4 years, 6 months ago

Pointer nf can be NULL. It should be validated before dereferencing it.

Fixes: 8628027ba8 ("nfs: block notification on fs with its own ->lock")
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
---
 fs/nfsd/nfs4state.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index a526d4183348..bdd30988e615 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -6947,6 +6947,11 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		goto out;
 	}
 
+	if (!nf) {
+		status = nfserr_openmode;
+		goto out;
+	}
+
 	/*
 	 * Most filesystems with their own ->lock operations will block
 	 * the nfsd thread waiting to acquire the lock.  That leads to
@@ -6957,11 +6962,6 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	if (nf->nf_file->f_op->lock)
 		fl_flags &= ~FL_SLEEP;
 
-	if (!nf) {
-		status = nfserr_openmode;
-		goto out;
-	}
-
 	nbl = find_or_allocate_block(lock_sop, &fp->fi_fhandle, nn);
 	if (!nbl) {
 		dprintk("NFSD: %s: unable to allocate block!\n", __func__);
-- 
2.30.2

Re: [PATCH] nfs: check nf pointer for validity before use

Posted by Chuck Lever III 4 years, 6 months ago

Hi-

> On Dec 21, 2021, at 1:55 PM, Muhammad Usama Anjum <usama.anjum@collabora.com> wrote:
> 
> Pointer nf can be NULL. It should be validated before dereferencing it.
> 
> Fixes: 8628027ba8 ("nfs: block notification on fs with its own ->lock")
> Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>

Thanks. To avoid confusion I've squashed this into 8628027 and
refreshed my for-next branch.

Btw, b4 complained about collabora.com's DKIM:

[cel@bazille linux]$ b4 am https://lore.kernel.org/linux-nfs/YcIjJ4jN3ax1rqaE@debian-BULLSEYE-live-builder-AMD64/raw
Grabbing thread from lore.kernel.org/linux-nfs/YcIjJ4jN3ax1rqaE%40debian-BULLSEYE-live-builder-AMD64/t.mbox.gz
Analyzing 1 messages in the thread
Checking attestation on all messages, may take a moment...
---
  ✗ [PATCH] nfs: check nf pointer for validity before use
  ---
  ✗ BADSIG: DKIM/collabora.com
---
Total patches: 1
---
 Link: https://lore.kernel.org/r/YcIjJ4jN3ax1rqaE@debian-BULLSEYE-live-builder-AMD64
 Base: not specified
       git am ./20211221_usama_anjum_nfs_check_nf_pointer_for_validity_before_use.mbx
[cel@bazille linux]$

The patch is obviously correct, so I applied it despite the
attestation failure.


> ---
> fs/nfsd/nfs4state.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index a526d4183348..bdd30988e615 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -6947,6 +6947,11 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> 		goto out;
> 	}
> 
> +	if (!nf) {
> +		status = nfserr_openmode;
> +		goto out;
> +	}
> +
> 	/*
> 	 * Most filesystems with their own ->lock operations will block
> 	 * the nfsd thread waiting to acquire the lock.  That leads to
> @@ -6957,11 +6962,6 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> 	if (nf->nf_file->f_op->lock)
> 		fl_flags &= ~FL_SLEEP;
> 
> -	if (!nf) {
> -		status = nfserr_openmode;
> -		goto out;
> -	}
> -
> 	nbl = find_or_allocate_block(lock_sop, &fp->fi_fhandle, nn);
> 	if (!nbl) {
> 		dprintk("NFSD: %s: unable to allocate block!\n", __func__);
> -- 
> 2.30.2
> 

--
Chuck Lever

Re: [PATCH] nfs: check nf pointer for validity before use

Posted by Konstantin Ryabitsev 4 years, 6 months ago

December 21, 2021 3:00 PM, "Chuck Lever III" <chuck.lever@oracle.com> wrote:
> Btw, b4 complained about collabora.com's DKIM:
> 
> [cel@bazille linux]$ b4 am
> https://lore.kernel.org/linux-nfs/YcIjJ4jN3ax1rqaE@debian-BULLSEYE-live-builder-AMD64/raw
> Grabbing thread from
> lore.kernel.org/linux-nfs/YcIjJ4jN3ax1rqaE%40debian-BULLSEYE-live-builder-AMD64/t.mbox.gz
> Analyzing 1 messages in the thread
> Checking attestation on all messages, may take a moment...
> ---
> ✗ [PATCH] nfs: check nf pointer for validity before use
> ---
> ✗ BADSIG: DKIM/collabora.com

This is because collabora.com has DKIM canonicalization configured as "c=simple/simple". See my previous message to intel.com for why this should be changed to c=relaxed/simple:

https://lore.kernel.org/lkml/20211214150032.nioelgvmase7yyus@meerkat.local/

Hope this helps.

-K

Re: [PATCH] nfs: check nf pointer for validity before use

Posted by Tomeu Vizoso 4 years, 6 months ago

On 12/21/21 11:18 PM, Konstantin Ryabitsev wrote:
> December 21, 2021 3:00 PM, "Chuck Lever III" <chuck.lever@oracle.com> wrote:
>> Btw, b4 complained about collabora.com's DKIM:
>>
>> [cel@bazille linux]$ b4 am
>> https://lore.kernel.org/linux-nfs/YcIjJ4jN3ax1rqaE@debian-BULLSEYE-live-builder-AMD64/raw
>> Grabbing thread from
>> lore.kernel.org/linux-nfs/YcIjJ4jN3ax1rqaE%40debian-BULLSEYE-live-builder-AMD64/t.mbox.gz
>> Analyzing 1 messages in the thread
>> Checking attestation on all messages, may take a moment...
>> ---
>> ✗ [PATCH] nfs: check nf pointer for validity before use
>> ---
>> ✗ BADSIG: DKIM/collabora.com
> 
> This is because collabora.com has DKIM canonicalization configured as "c=simple/simple". See my previous message to intel.com for why this should be changed to c=relaxed/simple:
> 
> https://lore.kernel.org/lkml/20211214150032.nioelgvmase7yyus@meerkat.local/

Thank you both, Chuck and Konstantin,

I have forwarded this conversation to our sysadmin team.

Best regards,

Tomeu