git: 542711e52079 - main - Fix a vnode locking bug in fuse_vnop_advlock.

[Alan Somers]

The branch main has been updated by asomers:

URL: https://cgit.FreeBSD.org/src/commit/?id=542711e52079f65647ac1daadf0c9e74cb221f3e

commit 542711e52079f65647ac1daadf0c9e74cb221f3e
Author:     Alan Somers <asomers at FreeBSD.org>
AuthorDate: 2020-12-30 23:50:35 +0000
Commit:     Alan Somers <asomers at FreeBSD.org>
CommitDate: 2021-01-03 16:16:23 +0000

    Fix a vnode locking bug in fuse_vnop_advlock.
    
    Must lock the vnode before accessing the fufh table.  Also, check for
    invalid parameters earlier.  Bug introduced by r346170.
    
    MFC after:      2 weeks
    
    Reviewed by:    cem
    Differential Revision:  https://reviews.freebsd.org/D27936
---
 sys/fs/fuse/fuse_vnops.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/sys/fs/fuse/fuse_vnops.c b/sys/fs/fuse/fuse_vnops.c
index 1e9434f9403d..437236882457 100644
--- a/sys/fs/fuse/fuse_vnops.c
+++ b/sys/fs/fuse/fuse_vnops.c
@@ -432,18 +432,6 @@ fuse_vnop_advlock(struct vop_advlock_args *ap)
 		return ENXIO;
 	}
 
-	if (!(dataflags & FSESS_POSIX_LOCKS))
-		return vop_stdadvlock(ap);
-	/* FUSE doesn't properly support flock until protocol 7.17 */
-	if (flags & F_FLOCK)
-		return vop_stdadvlock(ap);
-
-	err = fuse_filehandle_get_anyflags(vp, &fufh, cred, pid);
-	if (err)
-		return err;
-
-	fdisp_init(&fdi, sizeof(*fli));
-
 	switch(ap->a_op) {
 	case F_GETLK:
 		op = FUSE_GETLK;
@@ -458,6 +446,20 @@ fuse_vnop_advlock(struct vop_advlock_args *ap)
 		return EINVAL;
 	}
 
+	if (!(dataflags & FSESS_POSIX_LOCKS))
+		return vop_stdadvlock(ap);
+	/* FUSE doesn't properly support flock until protocol 7.17 */
+	if (flags & F_FLOCK)
+		return vop_stdadvlock(ap);
+
+	vn_lock(vp, LK_SHARED | LK_RETRY);
+
+	err = fuse_filehandle_get_anyflags(vp, &fufh, cred, pid);
+	if (err)
+		goto out;
+
+	fdisp_init(&fdi, sizeof(*fli));
+
 	fdisp_make_vp(&fdi, op, vp, td, cred);
 	fli = fdi.indata;
 	fli->fh = fufh->fh_id;
@@ -487,6 +489,8 @@ fuse_vnop_advlock(struct vop_advlock_args *ap)
 		}
 	}
 
+out:
+	VOP_UNLOCK(vp);
 	return err;
 }