Patch "NFSD: fix missing refcount in nfsd4_copy by nfsd4_do_async_copy" has been added to the 5.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    NFSD: fix missing refcount in nfsd4_copy by nfsd4_do_async_copy

to the 5.9-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-fix-missing-refcount-in-nfsd4_copy-by-nfsd4_do_.patch
and it can be found in the queue-5.9 subdirectory.

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



commit a2e97aa8a22b05b1c871320863abca53983eba0b
Author: Dai Ngo <dai.ngo@xxxxxxxxxx>
Date:   Thu Oct 29 15:07:16 2020 -0400

    NFSD: fix missing refcount in nfsd4_copy by nfsd4_do_async_copy
    
    [ Upstream commit 49a361327332c9221438397059067f9b205f690d ]
    
    Need to initialize nfsd4_copy's refcount to 1 to avoid use-after-free
    warning when nfs4_put_copy is called from nfsd4_cb_offload_release.
    
    Fixes: ce0887ac96d3 ("NFSD add nfs4 inter ssc to nfsd4_copy")
    Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
    Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 80effaa18b7b2..3ba17b5fc9286 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1486,6 +1486,7 @@ do_callback:
 	cb_copy = kzalloc(sizeof(struct nfsd4_copy), GFP_KERNEL);
 	if (!cb_copy)
 		goto out;
+	refcount_set(&cb_copy->refcount, 1);
 	memcpy(&cb_copy->cp_res, &copy->cp_res, sizeof(copy->cp_res));
 	cb_copy->cp_clp = copy->cp_clp;
 	cb_copy->nfserr = copy->nfserr;