This is a note to let you know that I've just added the patch titled NFSD: Fix use-after-free warning when doing inter-server 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-use-after-free-warning-when-doing-inter-ser.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 0b4977be487eabbdecf6197ef023ded08055b663 Author: Dai Ngo <dai.ngo@xxxxxxxxxx> Date: Thu Oct 29 15:07:15 2020 -0400 NFSD: Fix use-after-free warning when doing inter-server copy [ Upstream commit 36e1e5ba90fb3fba6888fae26e4dfc28bf70aaf1 ] The source file nfsd_file is not constructed the same as other nfsd_file's via nfsd_file_alloc. nfsd_file_put should not be called to free the object; nfsd_file_put is not the inverse of kzalloc, instead kfree is called by nfsd4_do_async_copy when done. 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 84e10aef14175..80effaa18b7b2 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -1299,7 +1299,7 @@ nfsd4_cleanup_inter_ssc(struct vfsmount *ss_mnt, struct nfsd_file *src, struct nfsd_file *dst) { nfs42_ssc_close(src->nf_file); - nfsd_file_put(src); + /* 'src' is freed by nfsd4_do_async_copy */ nfsd_file_put(dst); mntput(ss_mnt); }