Messages in this thread | | | Date | Thu, 16 Feb 2006 00:56:09 -0300 | From | Davi Arnaut <> | Subject | Re: [PATCH 0/2] strndup_user, v2 |
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On Thu, 16 Feb 2006 01:25:56 +0000 Alan Cox <alan@lxorguk.ukuu.org.uk> 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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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