Patch "nfsd: clean up potential nfsd_file refcount leaks in COPY codepath" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    nfsd: clean up potential nfsd_file refcount leaks in COPY codepath

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfsd-clean-up-potential-nfsd_file-refcount-leaks-in-.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 23d44b6ec2bb8ae064027d244d106317c44d97c8
Author: Jeff Layton <jlayton@xxxxxxxxxx>
Date:   Tue Jan 17 14:38:31 2023 -0500

    nfsd: clean up potential nfsd_file refcount leaks in COPY codepath
    
    [ Upstream commit 6ba434cb1a8d403ea9aad1b667c3ea3ad8b3191f ]
    
    There are two different flavors of the nfsd4_copy struct. One is
    embedded in the compound and is used directly in synchronous copies. The
    other is dynamically allocated, refcounted and tracked in the client
    struture. For the embedded one, the cleanup just involves releasing any
    nfsd_files held on its behalf. For the async one, the cleanup is a bit
    more involved, and we need to dequeue it from lists, unhash it, etc.
    
    There is at least one potential refcount leak in this code now. If the
    kthread_create call fails, then both the src and dst nfsd_files in the
    original nfsd4_copy object are leaked.
    
    The cleanup in this codepath is also sort of weird. In the async copy
    case, we'll have up to four nfsd_file references (src and dst for both
    flavors of copy structure). They are both put at the end of
    nfsd4_do_async_copy, even though the ones held on behalf of the embedded
    one outlive that structure.
    
    Change it so that we always clean up the nfsd_file refs held by the
    embedded copy structure before nfsd4_copy returns. Rework
    cleanup_async_copy to handle both inter and intra copies. Eliminate
    nfsd4_cleanup_intra_ssc since it now becomes a no-op.
    
    Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
    Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
    Stable-dep-of: 81e722978ad2 ("NFSD: fix problems with cleanup on errors in nfsd4_copy")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 32652b5e6eff3..043cef25d3dbd 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1523,7 +1523,6 @@ nfsd4_cleanup_inter_ssc(struct nfsd4_ssc_umount_item *nsui, struct file *filp,
 	long timeout = msecs_to_jiffies(nfsd4_ssc_umount_timeout);
 
 	nfs42_ssc_close(filp);
-	nfsd_file_put(dst);
 	fput(filp);
 
 	spin_lock(&nn->nfsd_ssc_lock);
@@ -1573,13 +1572,6 @@ nfsd4_setup_intra_ssc(struct svc_rqst *rqstp,
 				 &copy->nf_dst);
 }
 
-static void
-nfsd4_cleanup_intra_ssc(struct nfsd_file *src, struct nfsd_file *dst)
-{
-	nfsd_file_put(src);
-	nfsd_file_put(dst);
-}
-
 static void nfsd4_cb_offload_release(struct nfsd4_callback *cb)
 {
 	struct nfsd4_cb_offload *cbo =
@@ -1694,12 +1686,18 @@ static void dup_copy_fields(struct nfsd4_copy *src, struct nfsd4_copy *dst)
 	dst->ss_nsui = src->ss_nsui;
 }
 
+static void release_copy_files(struct nfsd4_copy *copy)
+{
+	if (copy->nf_src)
+		nfsd_file_put(copy->nf_src);
+	if (copy->nf_dst)
+		nfsd_file_put(copy->nf_dst);
+}
+
 static void cleanup_async_copy(struct nfsd4_copy *copy)
 {
 	nfs4_free_copy_state(copy);
-	nfsd_file_put(copy->nf_dst);
-	if (!nfsd4_ssc_is_inter(copy))
-		nfsd_file_put(copy->nf_src);
+	release_copy_files(copy);
 	spin_lock(&copy->cp_clp->async_lock);
 	list_del(&copy->copies);
 	spin_unlock(&copy->cp_clp->async_lock);
@@ -1759,7 +1757,6 @@ static int nfsd4_do_async_copy(void *data)
 	} else {
 		nfserr = nfsd4_do_copy(copy, copy->nf_src->nf_file,
 				       copy->nf_dst->nf_file, false);
-		nfsd4_cleanup_intra_ssc(copy->nf_src, copy->nf_dst);
 	}
 
 do_callback:
@@ -1822,9 +1819,9 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	} else {
 		status = nfsd4_do_copy(copy, copy->nf_src->nf_file,
 				       copy->nf_dst->nf_file, true);
-		nfsd4_cleanup_intra_ssc(copy->nf_src, copy->nf_dst);
 	}
 out:
+	release_copy_files(copy);
 	return status;
 out_err:
 	if (nfsd4_ssc_is_inter(copy)) {