On Thu, 16 Feb 2006 01:25:56 +0000
Alan Cox <[email protected]> wrote:
> On Mer, 2006-02-15 at 18:22 -0300, Davi Arnaut wrote:
> > +static inline char *strdup_user(const char __user *s)
> > +{
> > + return strndup_user(s, 4096);
> > +}
>
> Still shouldn't exist. Its just a bad idea to give people broken
> function they don't yet use.
Ok, I will remove it. But it's a sane default, if someone wants more
than 4096, they should use strndup_user.
> > + length = strlen_user(s);
>
> Should use strnlen_user or this function is useless for most cases.
Ok.
> > +
> > + if (!length)
> > + return ERR_PTR(-EFAULT);
>
> Zero isn't an -EFAULT length. Its a null string and valid
strlen_user returns _0_ on exception. If you don't belive me,
kernel/module.c or arch/x86_64/lib/usercopy.c are a good starting
point.
> > +
> > + if (length > n)
> > + length = n;
> > +
> > + p = kmalloc(length, GFP_KERNEL);
> > +
> > + if (!p)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + if (strncpy_from_user(p, s, length) < 0) {
> > + kfree(p);
> > + return ERR_PTR(-EFAULT);
> > + }
> > +
> > + p[length - 1] = '\0';
>
> And still broken.
>
> "Hello" -> length = 5 "Hello\0"[4] = 0 "Hell"
>
NO! strlen_user("Hello") -> length = 6
strlen_user returns the size of the string INCLUDING the
terminating NUL.
Are we talking in the same language ?
--
Davi Arnaut
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