* [PATCH 1/8] vfs: fix too big f_pos handling
@ 2010-01-13 14:09 Wu, Fengguang
2010-01-14 5:13 ` Al Viro
0 siblings, 1 reply; 4+ messages in thread
From: Wu, Fengguang @ 2010-01-13 14:09 UTC (permalink / raw)
To: Andrew Morton
Cc: Wu, Fengguang, LKML, Heiko Carstens, KAMEZAWA Hiroyuki,
Andi Kleen, Nick Piggin, Hugh Dickins,
Linux Memory Management List, linux-fsdevel
[CC fsdevel for opinions]
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).
This patch introduce a flag S_VERYBIG and allow negative file
offsets.
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: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-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 | 22 ++++++++++++++++++++--
include/linux/fs.h | 2 ++
4 files changed, 28 insertions(+), 2 deletions(-)
--- linux-mm.orig/fs/read_write.c 2010-01-13 21:23:04.000000000 +0800
+++ linux-mm/fs/read_write.c 2010-01-13 21:23:52.000000000 +0800
@@ -205,6 +205,21 @@ bad:
}
#endif
+static int
+__negative_fpos_check(struct inode *inode, 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 !VERYBIG inode, negative pos(pos+count) is not allowed */
+ if (!IS_VERYBIG(inode))
+ return -EINVAL;
+ return 0;
+}
+
/*
* rw_verify_area doesn't like huge counts. We limit
* them to something that fits in "int" so that others
@@ -222,8 +237,11 @@ 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(inode, pos, count);
+ if (retval)
+ return retval;
+ }
if (unlikely(inode->i_flock && mandatory_lock(inode))) {
retval = locks_mandatory_area(
--- linux-mm.orig/include/linux/fs.h 2010-01-13 21:23:04.000000000 +0800
+++ linux-mm/include/linux/fs.h 2010-01-13 21:31:02.000000000 +0800
@@ -235,6 +235,7 @@ struct inodes_stat_t {
#define S_NOCMTIME 128 /* Do not update file c/mtime */
#define S_SWAPFILE 256 /* Do not truncate: swapon got its bmaps */
#define S_PRIVATE 512 /* Inode is fs-internal */
+#define S_VERYBIG 1024 /* Inode is huge: treat loff_t as unsigned */
/*
* Note that nosuid etc flags are inode-specific: setting some file-system
@@ -269,6 +270,7 @@ struct inodes_stat_t {
#define IS_NOCMTIME(inode) ((inode)->i_flags & S_NOCMTIME)
#define IS_SWAPFILE(inode) ((inode)->i_flags & S_SWAPFILE)
#define IS_PRIVATE(inode) ((inode)->i_flags & S_PRIVATE)
+#define IS_VERYBIG(inode) ((inode)->i_flags & S_VERYBIG)
/* the read-only stuff doesn't really belong here, but any other place is
probably as bad and I don't want to create yet another include file. */
--- linux-mm.orig/drivers/char/mem.c 2010-01-13 21:23:11.000000000 +0800
+++ linux-mm/drivers/char/mem.c 2010-01-13 21:27:28.000000000 +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)
+ inode->i_flags |= S_VERYBIG;
+
if (dev->fops->open)
return dev->fops->open(inode, filp);
--- linux-mm.orig/fs/proc/base.c 2010-01-13 21:23:04.000000000 +0800
+++ linux-mm/fs/proc/base.c 2010-01-13 21:27:51.000000000 +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);
+ /* this file is read only and we can catch out-of-range */
+ inode->i_flags |= S_VERYBIG;
return 0;
}
--
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 1/8] vfs: fix too big f_pos handling
2010-01-13 14:09 [PATCH 1/8] vfs: fix too big f_pos handling Wu, Fengguang
@ 2010-01-14 5:13 ` Al Viro
2010-01-14 5:42 ` KAMEZAWA Hiroyuki
0 siblings, 1 reply; 4+ messages in thread
From: Al Viro @ 2010-01-14 5:13 UTC (permalink / raw)
To: Wu, Fengguang
Cc: Andrew Morton, LKML, Heiko Carstens, KAMEZAWA Hiroyuki,
Andi Kleen, Nick Piggin, Hugh Dickins,
Linux Memory Management List, linux-fsdevel
On Wed, Jan 13, 2010 at 10:09:56PM +0800, Wu, Fengguang wrote:
> 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).
>
> This patch introduce a flag S_VERYBIG and allow negative file
> offsets.
Ehh... FMODE_NEG_OFFSET in file->f_mode, perhaps?
--
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 1/8] vfs: fix too big f_pos handling
2010-01-14 5:13 ` Al Viro
@ 2010-01-14 5:42 ` KAMEZAWA Hiroyuki
2010-01-14 13:56 ` Wu Fengguang
0 siblings, 1 reply; 4+ messages in thread
From: KAMEZAWA Hiroyuki @ 2010-01-14 5:42 UTC (permalink / raw)
To: Al Viro
Cc: Wu, Fengguang, Andrew Morton, LKML, Heiko Carstens, Andi Kleen,
Nick Piggin, Hugh Dickins, Linux Memory Management List,
linux-fsdevel
On Thu, 14 Jan 2010 05:13:08 +0000
Al Viro <viro@ZenIV.linux.org.uk> wrote:
> On Wed, Jan 13, 2010 at 10:09:56PM +0800, Wu, Fengguang wrote:
> > 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).
> >
> > This patch introduce a flag S_VERYBIG and allow negative file
> > offsets.
>
> Ehh... FMODE_NEG_OFFSET in file->f_mode, perhaps?
>
Any method is okay for me.
I was just not sure where I could modify without problem.
If modifing f_mode is allowed, I'll write new version.
Thank you for advice.
I'm sorry that I don't have enough time this week. So, I'll try next week.
I think dropping this patch itself has no big influence to this patch set.
(but debug will be harder ;)
Thanks,
-Kame
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 1/8] vfs: fix too big f_pos handling
2010-01-14 5:42 ` KAMEZAWA Hiroyuki
@ 2010-01-14 13:56 ` Wu Fengguang
0 siblings, 0 replies; 4+ messages in thread
From: Wu Fengguang @ 2010-01-14 13:56 UTC (permalink / raw)
To: KAMEZAWA Hiroyuki
Cc: Al Viro, Andrew Morton, LKML, Heiko Carstens, Andi Kleen,
Nick Piggin, Hugh Dickins, Linux Memory Management List,
linux-fsdevel@vger.kernel.org
On Thu, Jan 14, 2010 at 01:42:50PM +0800, KAMEZAWA Hiroyuki wrote:
> On Thu, 14 Jan 2010 05:13:08 +0000
> Al Viro <viro@ZenIV.linux.org.uk> wrote:
>
> > On Wed, Jan 13, 2010 at 10:09:56PM +0800, Wu, Fengguang wrote:
> > > 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).
> > >
> > > This patch introduce a flag S_VERYBIG and allow negative file
> > > offsets.
> >
> > Ehh... FMODE_NEG_OFFSET in file->f_mode, perhaps?
> >
> Any method is okay for me.
> I was just not sure where I could modify without problem.
> If modifing f_mode is allowed, I'll write new version.
>
> Thank you for advice.
>
> I'm sorry that I don't have enough time this week. So, I'll try next week.
> I think dropping this patch itself has no big influence to this patch set.
> (but debug will be harder ;)
I just added FMODE_RANDOM, so hands down to add another ;)
Here is the updated patch, I'd like to submit it in another series
together with the FMODE_RANDOM patch.
Tested OK on /dev/kmem.
Thanks,
Fengguang
---
Subject: vfs: allow negative f_pos with FMODE_NEG_OFFSET
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;
}
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2010-01-13 14:09 [PATCH 1/8] vfs: fix too big f_pos handling Wu, Fengguang
2010-01-14 5:13 ` Al Viro
2010-01-14 5:42 ` KAMEZAWA Hiroyuki
2010-01-14 13:56 ` Wu Fengguang
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