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From: Takuya Yoshikawa on 3 Jun 2010 06:20
(2010/06/03 19:04), Dan Carpenter wrote:
> copy_to_user() returns the number of bytes remaining, but we want to
> return -EFAULT.
>
> ret = fcntl(fd, F_SETOWN_EX, NULL);
>
> With the original code ret would be 8 here.
>
> Signed-off-by: Dan Carpenter<error27(a)gmail.com>

How about f_getown_ex() ?

if (!ret)
ret = copy_to_user(owner_p, &owner, sizeof(owner));
return ret;

Fixing this too would be better, I think.

Takuya

>
> diff --git a/fs/fcntl.c b/fs/fcntl.c
> index f74d270..0ea7b0f 100644
> --- a/fs/fcntl.c
> +++ b/fs/fcntl.c
> @@ -274,7 +274,7 @@ static int f_setown_ex(struct file *filp, unsigned long arg)
>
> ret = copy_from_user(&owner, owner_p, sizeof(owner));
> if (ret)
> - return ret;
> + return -EFAULT;
>
> switch (owner.type) {
> case F_OWNER_TID:
> --
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From: Peter Zijlstra on 3 Jun 2010 06:50
On Thu, 2010-06-03 at 12:35 +0200, Dan Carpenter wrote:
> copy_to_user() returns the number of bytes remaining, but we want to
> return -EFAULT.
> ret = fcntl(fd, F_SETOWN_EX, NULL);
> With the original code ret would be 8 here.
>
> V2: Takuya Yoshikawa pointed out a similar issue in f_getown_ex()
>
> Signed-off-by: Dan Carpenter <error27(a)gmail.com>

Acked-by: Peter Zijlstra <a.p.zijlstra(a)chello.nl>

> diff --git a/fs/fcntl.c b/fs/fcntl.c
> index f74d270..51e11bf 100644
> --- a/fs/fcntl.c
> +++ b/fs/fcntl.c
> @@ -274,7 +274,7 @@ static int f_setown_ex(struct file *filp, unsigned long arg)
>
> ret = copy_from_user(&owner, owner_p, sizeof(owner));
> if (ret)
> - return ret;
> + return -EFAULT;
>
> switch (owner.type) {
> case F_OWNER_TID:
> @@ -332,8 +332,11 @@ static int f_getown_ex(struct file *filp, unsigned long arg)
> }
> read_unlock(&filp->f_owner.lock);
>
> - if (!ret)
> + if (!ret) {
> ret = copy_to_user(owner_p, &owner, sizeof(owner));
> + if (ret)
> + ret = -EFAULT;
> + }
> return ret;
> }
>

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From: Jens Axboe on 3 Jun 2010 08:00
On 2010-06-03 12:35, Dan Carpenter wrote:
> copy_to_user() returns the number of bytes remaining, but we want to
> return -EFAULT.
> ret = fcntl(fd, F_SETOWN_EX, NULL);
> With the original code ret would be 8 here.
>
> V2: Takuya Yoshikawa pointed out a similar issue in f_getown_ex()

Pretty basic bug, how long has this been there?

Acked-by: Jens Axboe <jaxboe(a)fusionio.com>

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Jens Axboe

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From: Takuya Yoshikawa on 3 Jun 2010 08:20
(2010/06/03 20:59), Jens Axboe wrote:
> On 2010-06-03 12:35, Dan Carpenter wrote:
>> copy_to_user() returns the number of bytes remaining, but we want to
>> return -EFAULT.
>> ret = fcntl(fd, F_SETOWN_EX, NULL);
>> With the original code ret would be 8 here.
>>
>> V2: Takuya Yoshikawa pointed out a similar issue in f_getown_ex()
>
> Pretty basic bug, how long has this been there?

IIUC, from the beginning, when these were introduced.

And I recently sent similar bug fixes for other parts.

Ah, I also saw somebody sent cleanup patches using memdup_user() which does
not reside in uaccess.h.

Though I'm personally using private *_user documentation,
are there any good official doc for these?

Takuya



>
> Acked-by: Jens Axboe<jaxboe(a)fusionio.com>
>

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From: Eric Dumazet on 3 Jun 2010 08:40
Le jeudi 03 juin 2010 à 21:16 +0900, Takuya Yoshikawa a écrit :
> (2010/06/03 20:59), Jens Axboe wrote:
> > On 2010-06-03 12:35, Dan Carpenter wrote:
> >> copy_to_user() returns the number of bytes remaining, but we want to
> >> return -EFAULT.
> >> ret = fcntl(fd, F_SETOWN_EX, NULL);
> >> With the original code ret would be 8 here.
> >>
> >> V2: Takuya Yoshikawa pointed out a similar issue in f_getown_ex()
> >
> > Pretty basic bug, how long has this been there?
>
> IIUC, from the beginning, when these were introduced.

Maybe copy_to_user() was changed sometime to return a partial count
instead of EFAULT ?

I do think we should have a set of helper functions, instead of
spreading special EFAULT cases in one housand places...

This is really ugly.

static inline int sec_copy_to_user(arg1, arg2, arg3)
{
int res = copy_to_user(arg1, arg2, arg3);

return (res > 0) ? -EFAULT : res;
}



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