Module Name: src
Committed By: riastradh
Date: Sat Aug 6 21:21:10 UTC 2022
Modified Files:
src/sys/kern: vfs_vnops.c
Log Message:
vnodeops(9): Take exclusive lock in read/seek for f_offset update.
Otherwise concurrent readers/seekers might clobber it.
To generate a diff of this commit:
cvs rdiff -u -r1.234 -r1.235 src/sys/kern/vfs_vnops.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/vfs_vnops.c
diff -u src/sys/kern/vfs_vnops.c:1.234 src/sys/kern/vfs_vnops.c:1.235
--- src/sys/kern/vfs_vnops.c:1.234 Mon Jul 18 04:30:30 2022
+++ src/sys/kern/vfs_vnops.c Sat Aug 6 21:21:10 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_vnops.c,v 1.234 2022/07/18 04:30:30 thorpej Exp $ */
+/* $NetBSD: vfs_vnops.c,v 1.235 2022/08/06 21:21:10 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 1.234 2022/07/18 04:30:30 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_vnops.c,v 1.235 2022/08/06 21:21:10 riastradh Exp $");
#include "veriexec.h"
@@ -647,7 +647,10 @@ vn_read(file_t *fp, off_t *offset, struc
ioflag |= IO_ALTSEMANTICS;
if (fflag & FDIRECT)
ioflag |= IO_DIRECT;
- vn_lock(vp, LK_SHARED | LK_RETRY);
+ if (offset == &fp->f_offset && (flags & FOF_UPDATE_OFFSET) != 0)
+ vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
+ else
+ vn_lock(vp, LK_SHARED | LK_RETRY);
uio->uio_offset = *offset;
count = uio->uio_resid;
error = VOP_READ(vp, uio, ioflag, cred);
@@ -1135,7 +1138,10 @@ vn_seek(struct file *fp, off_t delta, in
if (vp->v_type == VFIFO)
return ESPIPE;
- vn_lock(vp, LK_SHARED | LK_RETRY);
+ if (flags & FOF_UPDATE_OFFSET)
+ vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
+ else
+ vn_lock(vp, LK_SHARED | LK_RETRY);
/* Compute the old and new offsets. */
oldoff = fp->f_offset;
