From: Chuck Lever <chuck.lever@oracle.com>
Date: Fri, 8 Jul 2022 18:27:09 +0000 (-0400)
Subject: NFSD: Ensure nf_inode is never dereferenced
X-Git-Tag: v6.6.17~6628^2~40
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=427f5f83a3191cbf024c5aea6e5b601cdf88d895;p=platform%2Fkernel%2Flinux-rpi.git

NFSD: Ensure nf_inode is never dereferenced

The documenting comment for struct nf_file states:

/*
 * A representation of a file that has been opened by knfsd. These are hashed
 * in the hashtable by inode pointer value. Note that this object doesn't
 * hold a reference to the inode by itself, so the nf_inode pointer should
 * never be dereferenced, only used for comparison.
 */

Replace the two existing dereferences to make the comment always
true.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 58721fc..57d06a2 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -228,12 +228,11 @@ nfsd_file_mark_put(struct nfsd_file_mark *nfm)
 }
 
 static struct nfsd_file_mark *
-nfsd_file_mark_find_or_create(struct nfsd_file *nf)
+nfsd_file_mark_find_or_create(struct nfsd_file *nf, struct inode *inode)
 {
 	int			err;
 	struct fsnotify_mark	*mark;
 	struct nfsd_file_mark	*nfm = NULL, *new;
-	struct inode *inode = nf->nf_inode;
 
 	do {
 		fsnotify_group_lock(nfsd_file_fsnotify_group);
@@ -1144,7 +1143,7 @@ out_status:
 
 open_file:
 	trace_nfsd_file_alloc(nf);
-	nf->nf_mark = nfsd_file_mark_find_or_create(nf);
+	nf->nf_mark = nfsd_file_mark_find_or_create(nf, key.inode);
 	if (nf->nf_mark) {
 		if (open) {
 			status = nfsd_open_verified(rqstp, fhp, may_flags,
diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h
index 28145f1..8e8c0c4 100644
--- a/fs/nfsd/filecache.h
+++ b/fs/nfsd/filecache.h
@@ -39,7 +39,7 @@ struct nfsd_file {
 #define NFSD_FILE_PENDING	(1)
 #define NFSD_FILE_REFERENCED	(2)
 	unsigned long		nf_flags;
-	struct inode		*nf_inode;
+	struct inode		*nf_inode;	/* don't deref */
 	refcount_t		nf_ref;
 	unsigned char		nf_may;
 	struct nfsd_file_mark	*nf_mark;
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 9d1a3e1..994bd11 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2564,7 +2564,7 @@ static void nfs4_show_fname(struct seq_file *s, struct nfsd_file *f)
 
 static void nfs4_show_superblock(struct seq_file *s, struct nfsd_file *f)
 {
-	struct inode *inode = f->nf_inode;
+	struct inode *inode = file_inode(f->nf_file);
 
 	seq_printf(s, "superblock: \"%02x:%02x:%ld\"",
 					MAJOR(inode->i_sb->s_dev),