netdev - [PATCH v3 32/32] NFSD: Ensure nf_inode is never dereferenced

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 08 Jul 2022 14:27:09 -0400
From:   Chuck Lever <chuck.lever@...cle.com>
To:     linux-nfs@...r.kernel.org, netdev@...r.kernel.org
Cc:     david@...morbit.com, jlayton@...hat.com, tgraf@...g.ch
Subject: [PATCH v3 32/32] 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.

Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
---
 fs/nfsd/filecache.c |    5 ++---
 fs/nfsd/filecache.h |    2 +-
 fs/nfsd/nfs4state.c |    2 +-
 3 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 36d61012d5de..11099c8918a4 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);
@@ -1164,7 +1163,7 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
 
 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 c5ddc877116b..d534b76cb65b 100644
--- a/fs/nfsd/filecache.h
+++ b/fs/nfsd/filecache.h
@@ -41,7 +41,7 @@ struct nfsd_file {
 #define NFSD_FILE_BREAK_WRITE	(3)
 #define NFSD_FILE_REFERENCED	(4)
 	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 9d1a3e131c49..994bd11bafe0 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),