git: 2bad237ec94f - stable/12 - nfsclient: Copy only initialized fields in nfs_getattr()

[Mark Johnston]

The branch stable/12 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=2bad237ec94f701e3041c146db136f03e6c89324

commit 2bad237ec94f701e3041c146db136f03e6c89324
Author:     Mark Johnston <markj at FreeBSD.org>
AuthorDate: 2021-05-04 12:53:57 +0000
Commit:     Mark Johnston <markj at FreeBSD.org>
CommitDate: 2021-05-11 00:28:22 +0000

    nfsclient: Copy only initialized fields in nfs_getattr()
    
    When loading attributes from the cache, the NFS client is careful to
    copy only the fields that it initialized.  After fetching attributes
    from the server, however, it would copy the entire vattr structure
    initialized from the RPC response, so uninitialized stack bytes would
    end up being copied to userspace.  In particular, va_birthtime (v2 and
    v3) and va_gen (v3) had this problem.
    
    Use a common subroutine to copy fields provided by the NFS client, and
    ensure that we provide a dummy va_gen for the v3 case.
    
    Reviewed by:    rmacklem
    Reported by:    KMSAN
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D30090
    
    (cherry picked from commit 8bde6d15d1fa9a947c2bdc5eddae36cfbb1076dc)
---
 sys/fs/nfs/nfsport.h             |  1 +
 sys/fs/nfsclient/nfs_clcomsubs.c |  1 +
 sys/fs/nfsclient/nfs_clport.c    | 24 +++++++++++++++++++++++-
 sys/fs/nfsclient/nfs_clvnops.c   | 19 ++-----------------
 4 files changed, 27 insertions(+), 18 deletions(-)

diff --git a/sys/fs/nfs/nfsport.h b/sys/fs/nfs/nfsport.h
index a0181df0bde7..5371f29d00de 100644
--- a/sys/fs/nfs/nfsport.h
+++ b/sys/fs/nfs/nfsport.h
@@ -880,6 +880,7 @@ int nfscl_loadattrcache(struct vnode **, struct nfsvattr *, void *, void *,
     int, int);
 int newnfs_realign(struct mbuf **, int);
 bool ncl_pager_setsize(struct vnode *vp, u_quad_t *nsizep);
+void ncl_copy_vattr(struct vattr *dst, struct vattr *src);
 
 /*
  * If the port runs on an SMP box that can enforce Atomic ops with low
diff --git a/sys/fs/nfsclient/nfs_clcomsubs.c b/sys/fs/nfsclient/nfs_clcomsubs.c
index e49b276ec66d..f0ac1a0b09ca 100644
--- a/sys/fs/nfsclient/nfs_clcomsubs.c
+++ b/sys/fs/nfsclient/nfs_clcomsubs.c
@@ -234,6 +234,7 @@ nfsm_loadattr(struct nfsrv_descript *nd, struct nfsvattr *nap)
 		fxdr_nfsv3time(&fp->fa3_ctime, &nap->na_ctime);
 		fxdr_nfsv3time(&fp->fa3_mtime, &nap->na_mtime);
 		nap->na_flags = 0;
+		nap->na_gen = 0;
 		nap->na_filerev = 0;
 	} else {
 		NFSM_DISSECT(fp, struct nfs_fattr *, NFSX_V2FATTR);
diff --git a/sys/fs/nfsclient/nfs_clport.c b/sys/fs/nfsclient/nfs_clport.c
index 7f6bbe622180..20500a290ff0 100644
--- a/sys/fs/nfsclient/nfs_clport.c
+++ b/sys/fs/nfsclient/nfs_clport.c
@@ -399,6 +399,28 @@ nfscl_warn_fileid(struct nfsmount *nmp, struct nfsvattr *oldnap,
 		    ncl_fileid_maxwarnings);
 }
 
+void
+ncl_copy_vattr(struct vattr *dst, struct vattr *src)
+{
+	dst->va_type = src->va_type;
+	dst->va_mode = src->va_mode;
+	dst->va_nlink = src->va_nlink;
+	dst->va_uid = src->va_uid;
+	dst->va_gid = src->va_gid;
+	dst->va_fsid = src->va_fsid;
+	dst->va_fileid = src->va_fileid;
+	dst->va_size = src->va_size;
+	dst->va_blocksize = src->va_blocksize;
+	dst->va_atime = src->va_atime;
+	dst->va_mtime = src->va_mtime;
+	dst->va_ctime = src->va_ctime;
+	dst->va_gen = src->va_gen;
+	dst->va_flags = src->va_flags;
+	dst->va_rdev = src->va_rdev;
+	dst->va_bytes = src->va_bytes;
+	dst->va_filerev = src->va_filerev;
+}
+
 /*
  * Load the attribute cache (that lives in the nfsnode entry) with
  * the attributes of the second argument and
@@ -550,7 +572,7 @@ nfscl_loadattrcache(struct vnode **vpp, struct nfsvattr *nap, void *nvaper,
 		KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
 	}
 	if (vaper != NULL) {
-		NFSBCOPY((caddr_t)vap, (caddr_t)vaper, sizeof(*vap));
+		ncl_copy_vattr(vaper, vap);
 		if (np->n_flag & NCHG) {
 			if (np->n_flag & NACC)
 				vaper->va_atime = np->n_atim;
diff --git a/sys/fs/nfsclient/nfs_clvnops.c b/sys/fs/nfsclient/nfs_clvnops.c
index fadcf26c686a..17859a16424b 100644
--- a/sys/fs/nfsclient/nfs_clvnops.c
+++ b/sys/fs/nfsclient/nfs_clvnops.c
@@ -916,23 +916,8 @@ nfs_getattr(struct vop_getattr_args *ap)
 	 * First look in the cache.
 	 */
 	if (ncl_getattrcache(vp, &vattr) == 0) {
-		vap->va_type = vattr.va_type;
-		vap->va_mode = vattr.va_mode;
-		vap->va_nlink = vattr.va_nlink;
-		vap->va_uid = vattr.va_uid;
-		vap->va_gid = vattr.va_gid;
-		vap->va_fsid = vattr.va_fsid;
-		vap->va_fileid = vattr.va_fileid;
-		vap->va_size = vattr.va_size;
-		vap->va_blocksize = vattr.va_blocksize;
-		vap->va_atime = vattr.va_atime;
-		vap->va_mtime = vattr.va_mtime;
-		vap->va_ctime = vattr.va_ctime;
-		vap->va_gen = vattr.va_gen;
-		vap->va_flags = vattr.va_flags;
-		vap->va_rdev = vattr.va_rdev;
-		vap->va_bytes = vattr.va_bytes;
-		vap->va_filerev = vattr.va_filerev;
+		ncl_copy_vattr(vap, &vattr);
+
 		/*
 		 * Get the local modify time for the case of a write
 		 * delegation.