[src/trunk]: src/sys/kern sys/kern: Avoid fp->f_offset without the object (he...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/71951e5d29be
branches:  trunk
changeset: 1023496:71951e5d29be
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sat Sep 11 10:09:13 2021 +0000

description:
sys/kern: Avoid fp->f_offset without the object (here, vnode) lock.

diffstat:

 sys/kern/sys_descrip.c |  9 ++++++---
 sys/kern/vfs_vnops.c   |  7 ++++---
 2 files changed, 10 insertions(+), 6 deletions(-)

diffs (62 lines):

diff -r 625e8e22399e -r 71951e5d29be sys/kern/sys_descrip.c
--- a/sys/kern/sys_descrip.c    Sat Sep 11 10:08:55 2021 +0000
+++ b/sys/kern/sys_descrip.c    Sat Sep 11 10:09:13 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sys_descrip.c,v 1.37 2020/02/23 15:46:41 ad Exp $      */
+/*     $NetBSD: sys_descrip.c,v 1.38 2021/09/11 10:09:13 riastradh Exp $       */
 
 /*-
  * Copyright (c) 2008, 2020 The NetBSD Foundation, Inc.
@@ -67,7 +67,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_descrip.c,v 1.37 2020/02/23 15:46:41 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_descrip.c,v 1.38 2021/09/11 10:09:13 riastradh Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -243,8 +243,11 @@
                return error;
 
        vp = fp->f_vnode;
-       if (fl->l_whence == SEEK_CUR)
+       if (fl->l_whence == SEEK_CUR) {
+               vn_lock(vp, LK_SHARED | LK_RETRY);
                fl->l_start += fp->f_offset;
+               VOP_UNLOCK(vp);
+       }
 
        flg = F_POSIX;
        p = curproc;
diff -r 625e8e22399e -r 71951e5d29be sys/kern/vfs_vnops.c
--- a/sys/kern/vfs_vnops.c      Sat Sep 11 10:08:55 2021 +0000
+++ b/sys/kern/vfs_vnops.c      Sat Sep 11 10:09:13 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_vnops.c,v 1.222 2021/09/11 10:08:55 riastradh Exp $        */
+/*     $NetBSD: vfs_vnops.c,v 1.223 2021/09/11 10:09:13 riastradh Exp $        */
 
 /*-
  * Copyright (c) 2009 The NetBSD Foundation, Inc.
@@ -66,7 +66,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_vnops.c,v 1.222 2021/09/11 10:08:55 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_vnops.c,v 1.223 2021/09/11 10:09:13 riastradh Exp $");
 
 #include "veriexec.h"
 
@@ -817,10 +817,11 @@
                if (com == FIONREAD) {
                        vn_lock(vp, LK_SHARED | LK_RETRY);
                        error = VOP_GETATTR(vp, &vattr, kauth_cred_get());
+                       if (error == 0)
+                               *(int *)data = vattr.va_size - fp->f_offset;
                        VOP_UNLOCK(vp);
                        if (error)
                                return (error);
-                       *(int *)data = vattr.va_size - fp->f_offset;
                        return (0);
                }
                if ((com == FIONWRITE) || (com == FIONSPACE)) {