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Date:   Mon, 7 Feb 2022 21:25:08 +0100
From:   Stephen Kitt <steve@sk2.org>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>
Cc:     Miaohe Lin <linmiaohe@huawei.com>, <linux-kernel@vger.kernel.org>,
        <linux-mm@kvack.org>, Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] mm: Remove usercopy_warn()
Message-ID: <20220207212508.432a6894@heffalump.sk2.org>
In-Reply-To: <b6e9e005-1269-d591-77b0-7db2edd996f4@huawei.com>
References: <5f26643fc70b05f8455b60b99c30c17d635fa640.1644231910.git.christophe.leroy@csgroup.eu>
        <b6e9e005-1269-d591-77b0-7db2edd996f4@huawei.com>
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On Mon, 7 Feb 2022 20:25:19 +0800, Miaohe Lin <linmiaohe@huawei.com> wrote:

> On 2022/2/7 19:05, Christophe Leroy wrote:
> > Users of usercopy_warn() were removed by
> > commit 53944f171a89 ("mm: remove HARDENED_USERCOPY_FALLBACK")
> >=20
> > Remote it. =20
>=20
> s/Remote/Remove/
>=20
> Except the above nit, this patch looks good to me. Thanks.
>=20
> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>

Likewise,

Reviewed-by: Stephen Kitt <steve@sk2.org>


> >=20
> > Cc: Stephen Kitt <steve@sk2.org>
> > Cc: Kees Cook <keescook@chromium.org>
> > Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> > ---
> >  include/linux/uaccess.h |  2 --
> >  mm/usercopy.c           | 11 -----------
> >  2 files changed, 13 deletions(-)
> >=20
> > diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
> > index ac0394087f7d..bca27b4e5eb2 100644
> > --- a/include/linux/uaccess.h
> > +++ b/include/linux/uaccess.h
> > @@ -401,8 +401,6 @@ static inline void user_access_restore(unsigned long
> > flags) { } #endif
> > =20
> >  #ifdef CONFIG_HARDENED_USERCOPY
> > -void usercopy_warn(const char *name, const char *detail, bool to_user,
> > -		   unsigned long offset, unsigned long len);
> >  void __noreturn usercopy_abort(const char *name, const char *detail,
> >  			       bool to_user, unsigned long offset,
> >  			       unsigned long len);
> > diff --git a/mm/usercopy.c b/mm/usercopy.c
> > index d0d268135d96..e7b0cb49daa1 100644
> > --- a/mm/usercopy.c
> > +++ b/mm/usercopy.c
> > @@ -70,17 +70,6 @@ static noinline int check_stack_object(const void
> > *obj, unsigned long len)
> >   * kmem_cache_create_usercopy() function to create the cache (and
> >   * carefully audit the whitelist range).
> >   */
> > -void usercopy_warn(const char *name, const char *detail, bool to_user,
> > -		   unsigned long offset, unsigned long len)
> > -{
> > -	WARN_ONCE(1, "Bad or missing usercopy whitelist? Kernel memory
> > %s attempt detected %s %s%s%s%s (offset %lu, size %lu)!\n",
> > -		 to_user ? "exposure" : "overwrite",
> > -		 to_user ? "from" : "to",
> > -		 name ? : "unknown?!",
> > -		 detail ? " '" : "", detail ? : "", detail ? "'" : "",
> > -		 offset, len);
> > -}
> > -
> >  void __noreturn usercopy_abort(const char *name, const char *detail,
> >  			       bool to_user, unsigned long offset,
> >  			       unsigned long len)
> >  =20
>=20

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