From: Wu Fengguang <fengguang.wu@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
Al Viro <viro@zeniv.linux.org.uk>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Wu Fengguang <fengguang.wu@intel.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: <linux-fsdevel@vger.kernel.org>
Subject: [PATCH 6/6] vfs: introduce FMODE_NEG_OFFSET for allowing negative f_pos
Date: Fri, 15 Jan 2010 09:40:00 +0800 [thread overview]
Message-ID: <20100115014422.959401729@intel.com> (raw)
In-Reply-To: 20100115013954.311049665@intel.com
[-- Attachment #1: f_pos-fix --]
[-- Type: text/plain, Size: 3661 bytes --]
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Now, rw_verify_area() checsk f_pos is negative or not. And if
negative, returns -EINVAL.
But, some special files as /dev/(k)mem and /proc/<pid>/mem etc..
has negative offsets. And we can't do any access via read/write
to the file(device).
So introduce FMODE_NEG_OFFSET to allow negative file offsets.
Changelog: v5->v6
- use FMODE_NEG_OFFSET (suggested by Al)
- rebased onto 2.6.33-rc1
Changelog: v4->v5
- clean up patches dor /dev/mem.
- rebased onto 2.6.32-rc1
Changelog: v3->v4
- make changes in mem.c aligned.
- change __negative_fpos_check() to return int.
- fixed bug in "pos" check.
- added comments.
Changelog: v2->v3
- fixed bug in rw_verify_area (it cannot be compiled)
CC: Al Viro <viro@ZenIV.linux.org.uk>
CC: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
drivers/char/mem.c | 4 ++++
fs/proc/base.c | 2 ++
fs/read_write.c | 21 +++++++++++++++++++--
include/linux/fs.h | 3 +++
4 files changed, 28 insertions(+), 2 deletions(-)
--- linux.orig/fs/read_write.c 2010-01-14 21:28:00.000000000 +0800
+++ linux/fs/read_write.c 2010-01-14 21:30:41.000000000 +0800
@@ -205,6 +205,20 @@ bad:
}
#endif
+static int
+__negative_fpos_check(struct file *file, loff_t pos, size_t count)
+{
+ /*
+ * pos or pos+count is negative here, check overflow.
+ * too big "count" will be caught in rw_verify_area().
+ */
+ if ((pos < 0) && (pos + count < pos))
+ return -EOVERFLOW;
+ if (file->f_mode & FMODE_NEG_OFFSET)
+ return 0;
+ return -EINVAL;
+}
+
/*
* rw_verify_area doesn't like huge counts. We limit
* them to something that fits in "int" so that others
@@ -222,8 +236,11 @@ int rw_verify_area(int read_write, struc
if (unlikely((ssize_t) count < 0))
return retval;
pos = *ppos;
- if (unlikely((pos < 0) || (loff_t) (pos + count) < 0))
- return retval;
+ if (unlikely((pos < 0) || (loff_t) (pos + count) < 0)) {
+ retval = __negative_fpos_check(file, pos, count);
+ if (retval)
+ return retval;
+ }
if (unlikely(inode->i_flock && mandatory_lock(inode))) {
retval = locks_mandatory_area(
--- linux.orig/include/linux/fs.h 2010-01-14 21:28:00.000000000 +0800
+++ linux/include/linux/fs.h 2010-01-14 21:32:24.000000000 +0800
@@ -93,6 +93,9 @@ struct inodes_stat_t {
/* Expect random access pattern */
#define FMODE_RANDOM ((__force fmode_t)0x1000)
+/* File is huge (eg. /dev/kmem): treat loff_t as unsigned */
+#define FMODE_NEG_OFFSET ((__force fmode_t)0x2000)
+
/*
* The below are the various read and write types that we support. Some of
* them include behavioral modifiers that send information down to the
--- linux.orig/drivers/char/mem.c 2010-01-14 21:28:00.000000000 +0800
+++ linux/drivers/char/mem.c 2010-01-14 21:33:20.000000000 +0800
@@ -861,6 +861,10 @@ static int memory_open(struct inode *ino
if (dev->dev_info)
filp->f_mapping->backing_dev_info = dev->dev_info;
+ /* Is /dev/mem or /dev/kmem ? */
+ if (dev->dev_info == &directly_mappable_cdev_bdi)
+ filp->f_mode |= FMODE_NEG_OFFSET;
+
if (dev->fops->open)
return dev->fops->open(inode, filp);
--- linux.orig/fs/proc/base.c 2010-01-14 21:28:00.000000000 +0800
+++ linux/fs/proc/base.c 2010-01-14 21:37:08.000000000 +0800
@@ -861,6 +861,8 @@ static const struct file_operations proc
static int mem_open(struct inode* inode, struct file* file)
{
file->private_data = (void*)((long)current->self_exec_id);
+ /* OK to pass negative loff_t, we can catch out-of-range */
+ file->f_mode |= FMODE_NEG_OFFSET;
return 0;
}
next prev parent reply other threads:[~2010-01-15 1:49 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-15 1:39 [PATCH 0/6] FMODE_NONOTIFY, FMODE_RANDOM and FMODE_NEG_OFFSET bits Wu Fengguang
2010-01-15 1:39 ` [PATCH 1/6] fanotify: fix FMODE_NONOTIFY bit number Wu Fengguang
2010-01-15 1:39 ` [PATCH 2/6] bitops: compile time optimization for hweight_long(CONSTANT) Wu Fengguang
2010-01-15 1:39 ` [PATCH 3/6] vfs: O_* bit numbers uniqueness check Wu Fengguang
2010-01-15 1:39 ` [PATCH 4/6] vfs: take f_lock on modifying f_mode after open time Wu Fengguang
2010-01-15 1:39 ` [PATCH 5/6] readahead: introduce FMODE_RANDOM for POSIX_FADV_RANDOM Wu Fengguang
2010-01-15 1:40 ` Wu Fengguang [this message]
2010-01-16 12:54 ` [PATCH 6/6] vfs: introduce FMODE_NEG_OFFSET for allowing negative f_pos OGAWA Hirofumi
2010-01-18 0:15 ` KAMEZAWA Hiroyuki
2010-01-18 1:17 ` OGAWA Hirofumi
2010-01-18 1:25 ` KAMEZAWA Hiroyuki
2010-01-18 1:38 ` OGAWA Hirofumi
2010-01-18 2:00 ` KAMEZAWA Hiroyuki
2010-01-18 2:13 ` OGAWA Hirofumi
2010-01-18 2:30 ` KAMEZAWA Hiroyuki
2010-01-18 3:15 ` Wu, Fengguang
2010-01-18 3:22 ` KAMEZAWA Hiroyuki
2010-01-18 5:26 ` Wu, Fengguang
2010-01-19 0:37 ` KAMEZAWA Hiroyuki
2010-01-18 1:32 ` OGAWA Hirofumi
2010-01-18 1:49 ` KAMEZAWA Hiroyuki
2010-01-18 1:59 ` OGAWA Hirofumi
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