diff options
| -rw-r--r-- | share/man/man9/file.9 | 14 | ||||
| -rw-r--r-- | sys/kern/kern_descrip.c | 21 | ||||
| -rw-r--r-- | sys/kern/kern_event.c | 21 | ||||
| -rw-r--r-- | sys/sys/filedesc.h | 3 |
4 files changed, 49 insertions, 10 deletions
diff --git a/share/man/man9/file.9 b/share/man/man9/file.9 index d6d771088c0..e3bd8cc645d 100644 --- a/share/man/man9/file.9 +++ b/share/man/man9/file.9 @@ -1,4 +1,4 @@ -.\" $OpenBSD: file.9,v 1.21 2019/12/31 16:59:35 visa Exp $ +.\" $OpenBSD: file.9,v 1.22 2020/01/03 05:37:00 visa Exp $ .\" .\" Copyright (c) 2002 Artur Grabowski <art@openbsd.org> .\" All rights reserved. @@ -22,7 +22,7 @@ .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" -.Dd $Mdocdate: December 31 2019 $ +.Dd $Mdocdate: January 3 2020 $ .Dt FALLOC 9 .Os .Sh NAME @@ -32,6 +32,7 @@ .Nm FRELE , .Nm fd_getfile , .Nm fd_getfile_mode , +.Nm fd_checkclosed , .Nm getsock , .Nm getvnode .Nd an overview of file descriptor handling @@ -51,6 +52,8 @@ .Ft struct file * .Fn fd_getfile_mode "struct filedesc *fdp" "int fd" "int mode" .Ft int +.Fn fd_checkclosed "struct filedesc *fdp" "int fd" "struct file *fp" +.Ft int .Fn getsock "struct proc *p" "int fd" "struct file **fpp" .In sys/file.h .In sys/filedesc.h @@ -114,6 +117,13 @@ is like .Fn fd_getfile but also checks if the file has been opened with the given mode. .Pp +.Fn fd_checkclosed +checks if file descriptor +.Fa fd +has been closed and no longer points to file +.Fa fp . +The file must have been retrieved from the descriptor previously. +.Pp The files are extracted from the process context using the function .Fn getsock diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c index d967d543b38..a9adcb7a83e 100644 --- a/sys/kern/kern_descrip.c +++ b/sys/kern/kern_descrip.c @@ -1,4 +1,4 @@ -/* $OpenBSD: kern_descrip.c,v 1.192 2019/08/05 08:35:59 anton Exp $ */ +/* $OpenBSD: kern_descrip.c,v 1.193 2020/01/03 05:37:00 visa Exp $ */ /* $NetBSD: kern_descrip.c,v 1.42 1996/03/30 22:24:38 christos Exp $ */ /* @@ -262,6 +262,18 @@ fd_getfile_mode(struct filedesc *fdp, int fd, int mode) return (fp); } +int +fd_checkclosed(struct filedesc *fdp, int fd, struct file *fp) +{ + int closed; + + mtx_enter(&fdp->fd_fplock); + KASSERT(fd < fdp->fd_nfiles); + closed = (fdp->fd_ofiles[fd] != fp); + mtx_leave(&fdp->fd_fplock); + return (closed); +} + /* * System calls on descriptors. */ @@ -396,7 +408,7 @@ sys_fcntl(struct proc *p, void *v, register_t *retval) } */ *uap = v; int fd = SCARG(uap, fd); struct filedesc *fdp = p->p_fd; - struct file *fp, *fp2; + struct file *fp; struct vnode *vp; int i, tmp, newmin, flg = F_POSIX; struct flock fl; @@ -570,8 +582,7 @@ restart: goto out; } - fp2 = fd_getfile(fdp, fd); - if (fp != fp2) { + if (fd_checkclosed(fdp, fd, fp)) { /* * We have lost the race with close() or dup2(); * unlock, pretend that we've won the race and that @@ -583,8 +594,6 @@ restart: VOP_ADVLOCK(vp, fdp, F_UNLCK, &fl, F_POSIX); fl.l_type = F_UNLCK; } - if (fp2 != NULL) - FRELE(fp2, p); goto out; diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c index c634353caa5..3141af589ce 100644 --- a/sys/kern/kern_event.c +++ b/sys/kern/kern_event.c @@ -1,4 +1,4 @@ -/* $OpenBSD: kern_event.c,v 1.113 2019/12/31 14:09:56 visa Exp $ */ +/* $OpenBSD: kern_event.c,v 1.114 2020/01/03 05:37:00 visa Exp $ */ /*- * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org> @@ -724,6 +724,25 @@ again: knote_drop(kn, p); goto done; } + + /* + * If this is a file descriptor filter, check if + * fd was closed while the knote was being added. + * knote_fdclose() has missed kn if the function + * ran before kn appeared in kq_knlist. + */ + if (fops->f_isfd && + fd_checkclosed(fdp, kev->ident, kn->kn_fp)) { + /* + * Drop the knote silently without error + * because another thread might already have + * seen it. This corresponds to the insert + * happening in full before the close. + */ + kn->kn_fop->f_detach(kn); + knote_drop(kn, p); + goto done; + } } else { /* * The user may change some filter values after the diff --git a/sys/sys/filedesc.h b/sys/sys/filedesc.h index aaadd17ebbf..3faadaee551 100644 --- a/sys/sys/filedesc.h +++ b/sys/sys/filedesc.h @@ -1,4 +1,4 @@ -/* $OpenBSD: filedesc.h,v 1.41 2018/07/02 14:36:33 visa Exp $ */ +/* $OpenBSD: filedesc.h,v 1.42 2020/01/03 05:37:00 visa Exp $ */ /* $NetBSD: filedesc.h,v 1.14 1996/04/09 20:55:28 cgd Exp $ */ /* @@ -136,6 +136,7 @@ void fdcloseexec(struct proc *); struct file *fd_iterfile(struct file *, struct proc *); struct file *fd_getfile(struct filedesc *, int); struct file *fd_getfile_mode(struct filedesc *, int, int); +int fd_checkclosed(struct filedesc *, int, struct file *); int closef(struct file *, struct proc *); int getsock(struct proc *, int, struct file **); |