Prev: You Won $650,500.00.
Next: BUG when battery is removed before resuming from hibernation
From: Miklos Szeredi on 8 Jun 2010 11:20
On Tue, 08 Jun 2010, Miklos Szeredi wrote:
> From: Miklos Szeredi <mszeredi(a)suse.cz>
>
> As it stands this check compares the number of pages to the page size.
> This makes no sense and makes the fcntl fail in almost any sane case.
>
> Fix it by removing the check completely, round_pipe_size() will make
> sure that nr_pages >= 1 anyway.

Hmm, not quite true. It can actually return zero if round_pipe_size()
overflows unsigned int.

Updated patch below.

Thanks,
Miklos
----

From: Miklos Szeredi <mszeredi(a)suse.cz>
Subject: pipe: fix check in "set size" fcntl

As it stands this check compares the number of pages to the page size.
This makes no sense and makes the fcntl fail in almost any sane case.

Fix it by checking if nr_pages is not zero (it can become zero only if
arg is too big and round_pipe_size() overflows).

Signed-off-by: Miklos Szeredi <mszeredi(a)suse.cz>
---
fs/pipe.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

Index: linux-2.6/fs/pipe.c
===================================================================
--- linux-2.6.orig/fs/pipe.c 2010-06-08 16:48:18.000000000 +0200
+++ linux-2.6/fs/pipe.c 2010-06-08 17:12:04.000000000 +0200
@@ -1215,12 +1215,13 @@ long pipe_fcntl(struct file *file, unsig
size = round_pipe_size(arg);
nr_pages = size >> PAGE_SHIFT;

+ ret = -EINVAL;
+ if (!nr_pages)
+ goto out;
+
if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
ret = -EPERM;
goto out;
- } else if (nr_pages < PAGE_SIZE) {
- ret = -EINVAL;
- goto out;
}
ret = pipe_set_size(pipe, nr_pages);
break;


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
From: Jens Axboe on 8 Jun 2010 15:10
On 2010-06-08 17:14, Miklos Szeredi wrote:
> On Tue, 08 Jun 2010, Miklos Szeredi wrote:
>> From: Miklos Szeredi <mszeredi(a)suse.cz>
>>
>> As it stands this check compares the number of pages to the page size.
>> This makes no sense and makes the fcntl fail in almost any sane case.
>>
>> Fix it by removing the check completely, round_pipe_size() will make
>> sure that nr_pages >= 1 anyway.
>
> Hmm, not quite true. It can actually return zero if round_pipe_size()
> overflows unsigned int.
>
> Updated patch below.

Thanks, I'll get these tested and merged asap. The copy code
apparently wasn't well tested. And this fcntl() bug snuck in with the
API changes :/

--
Jens Axboe

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: You Won $650,500.00.
Next: BUG when battery is removed before resuming from hibernation