Re: verify_area(...) possible problem.

Gilbert, Douglas (douglas.gilbert@rbcds.com)
Tue, 13 Apr 1999 11:21:10 -0400

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Linus Thorvalds wrote:

> ... you can do
>
> error = access_ok(VERIFY_READ, p, 3*sizeof(*p));
> if (!error) {
> __put_user(a, p);
> __put_user(b, p+1);
> __put_user(c, p+2);
> }
>
> where the __xxx versions are faster but "unsafe" unless you have
> verified the area by hand first.

Can this be extended to:

error = access_ok(VERIFY_READ, p, 3*sizeof(*p));
if (! error) {
interruptible_sleep_on(&some_wait_queue);
...
__put_user(a, p);
__put_user(b, p+1);
__put_user(c, p+2);
}
??

Doug Gilbert

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Re: verify_area(...) possible problem.

Linus Thorvalds wrote:

> ... you can do
>
>        error = =3D access_ok(VERIFY_READ, p, 3*sizeof(*p));
>        if = (!error) {
>          = ;      __put_user(a, p);
>          = ;      __put_user(b, p+1);
>          = ;      __put_user(c, p+2);
>        = }
>
> where the __xxx versions are faster but = "unsafe" unless you have
> verified the area by hand first.

Can this be extended to:

        error =3D = access_ok(VERIFY_READ, p, 3*sizeof(*p));
        if (! = error) {
        =       interruptible_sleep_on(&some_wait_queue);
        =       ...
        =       __put_user(a, p);
        =       __put_user(b, = p+1);
        =       __put_user(c, = p+2);
        }
??

Doug Gilbert

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