From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELsf/OGax9ARD6rEdGCLcINqUclwmVhZvnrrd4PbdR4Z/YgPKm8pGjOa4vkrYq/7F6fQwv9E ARC-Seal: i=1; a=rsa-sha256; t=1520863584; cv=none; d=google.com; s=arc-20160816; b=XxZSr41SsdaUWJyEUPG0iFzryMfUA/M4x+tY1bANrM/zlFO09e3bAte0NAXZqNhqll cfv6XznLgm87VteIxVMy1EtJ6Gk8nGTWmyaqx+OQuQJ7ckq5L6GaenTBuQdFlZRNr86u EpI950mRLW13RMux2c2cAwPmrAekQqetJy4R7SCZAtpFKYoKxl1BXtuDhIWbVfdGIQAm u5HTt7AP9DGXYIEJD4Lef/sDRXsBdRL6W5XW935PtTHtXycGvmetz87jMES8N3KkAUuz CD5aZtiNWWuJJsZeNr+IAA4esPFKoTDPQ/oL9pX/JN4s9ShmaBe5BTGPCXWdH+a7JKID n4Hg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=references:cms-type:content-transfer-encoding:mime-version :in-reply-to:user-agent:message-id:date:subject:cc:to:from :dkim-signature:dkim-filter:arc-authentication-results; bh=H4Kw98VFcYEHxfPXww0A28t9pfjdaEXD8B8xN2MrQgc=; b=dizr1QD17eyIidWMw07aa8eQ873Tbc4dSFJcNt3k96iLFEUmwW7kXhO/9AmgbrCLU/ y3PQzG4MiU+4jzthswwnnLrnqsjPksWp7BC+x+b9/358jCT5DBPj6+wFd3UI8rJTF8zI 5FeujF2RAj6Qa0IIhTNtGe+/iphix4jxOnDbHt04oOdnfaGGtCTXZArGo37OBoGcj5/R oxLK5hqfQEXK74EglgK13WEHiW0YSI2BaUtYaF/O//1mpauRh9q2rYEjwT/HgLp7eDMZ Vdd7zCIV/YJcAvEonZqt0uvgy/f1jsnrL5P4jqi1qM11DRoQjEdK9iJH6yUZqkjIs/i7 97og== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@samsung.com header.s=mail20170921 header.b=re0F2vax; spf=pass (google.com: domain of b.zolnierkie@samsung.com designates 203.254.224.25 as permitted sender) smtp.mailfrom=b.zolnierkie@samsung.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=samsung.com Authentication-Results: mx.google.com; dkim=pass header.i=@samsung.com header.s=mail20170921 header.b=re0F2vax; spf=pass (google.com: domain of b.zolnierkie@samsung.com designates 203.254.224.25 as permitted sender) smtp.mailfrom=b.zolnierkie@samsung.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=samsung.com DKIM-Filter: OpenDKIM Filter v2.11.0 mailout2.samsung.com 20180312140621epoutp028644b45bc29acd417ee955316672d663~bMV6bNiqL3199431994epoutp02R X-AuditID: b6c32a38-adbff70000001054-a7-5aa6895db9de From: Bartlomiej Zolnierkiewicz To: Kees Cook Cc: Joao Moreira , Greg KH , Kernel Hardening , LKML , Daniel Micay , linux-fbdev@vger.kernel.org Subject: Re: [PATCH] vgacon: fix function prototypes Date: Mon, 12 Mar 2018 15:06:12 +0100 Message-id: <4831767.IeJWIvYDSU@amdc3058> User-Agent: KMail/4.13.3 (Linux/3.13.0-96-generic; KDE/4.13.3; x86_64; ; ) In-reply-to: MIME-version: 1.0 Content-transfer-encoding: quoted-printable Content-type: text/plain; charset="iso-8859-1" X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrLIsWRmVeSWpSXmKPExsWy7bCmnm5s57Iog10XxC1u/TaxaF68ns1i eccMVosz3bkWSz/9ZrM40feB1eLyrjlsDuwesxsusnjsnHWX3WP/3DXsHis7H7N5bD5d7fF5 k1wAWxSXTUpqTmZZapG+XQJXxowZU5gKnopX3J03ibWBcZ5QFyMnh4SAicSBp5PYuxi5OIQE djBK3F0+hxnC+c4o8f31ahaYqhXT37FAJHYzSrzb84sJJCEk8JVR4tbmQBCbTcBKYmL7KkYQ W0RAVeL7pWZmEJtZ4D2jxJnr+iC2MNCg/3/OgvWyANWcPP6WDcTmFdCUONJ9FcwWFfCS2LKv HayGUyBY4s3rd0wQNYISPybfY4GYqS3x5N0FVghbT+JKwwmw4yQEDrBJvP7SyA5xtYvEnq+3 mCBsYYlXx7cAxTmAbGmJS0dtIeqbGSW+7djDDFEzgVFiz3pouFhLHD5+EWoBn8S7rz2sEL28 Eh1tUCUeEt/W74QGkKPEh6190GC8wCgxYdpa5gmMsrOQ3D0Lyd2zkNy9gJF5FaNYakFxbnpq sWGBiV5xYm5xaV66XnJ+7iZGcKLQstjBuOeczyFGAQ5GJR5eg+ZlUUKsiWXFlbmHGCU4mJVE eO9oAoV4UxIrq1KL8uOLSnNSiw8xSnOwKInzBgS4RAkJpCeWpGanphakFsFkmTg4pRoYKyU2 Rz7qZFCK9+t6tuCnj8f8JKc15cEHGE+ueyhslXnH6LA/h2TSnKuq7BskspO4ut4EWR25JnL6 6Wm1Eudrbydqhn1IzVnrw/bwfmShX8Ep+e4+9ZdZD4+dO3nildTKqQlSPvvXnb3H6yule1Qx wsD218ll057+kLi28NKT3mDtz8n/7e/PUWIpzkg01GIuKk4EALBiyX8QAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrGLMWRmVeSWpSXmKPExsVy+t9jAd2YzmVRBgt2a1jc+m1i0bx4PZvF 8o4ZrBZnunMtln76zWZxou8Dq8XlXXPYHNg9ZjdcZPHYOesuu8f+uWvYPVZ2Pmbz2Hy62uPz JrkAtigum5TUnMyy1CJ9uwSujBkzpjAVPBWvuDtvEmsD4zyhLkZODgkBE4kV09+xdDFycQgJ 7GSUWHPpKQtIQkjgK6PEoY5iEJtNwEpiYvsqRhBbREBV4vulZmaQBmaB94wSM97sYQdJCANN +v/nLBOIzQJUdPL4WzYQm1dAU+JI91UwW1TAS2LLvnawGk6BYIm9/54yQSyrkeif/4YVol5Q 4sfke2BHMAtoSzx5d4EVwtaR6P3+jXkCI/8sJGWzkJTNQlK2gJF5FaNkakFxbnpusVGBYV5q uV5xYm5xaV66XnJ+7iZGYGhvO6zVt4Px/pL4Q4wCHIxKPLwdrcuihFgTy4orcw8xSnAwK4nw 3tEECvGmJFZWpRblxxeV5qQWH2KU5mBREue9nXcsUkggPbEkNTs1tSC1CCbLxMEp1cDoVGCe Mic8xnRqheEP+er1N2X9BCOqOJX007z+bj+5tUMzt+av/SvDTQweSV8SVP491nCb4PDrLevj xuk7mmZenDGpxstC+HNme46azdkrVdJpmbsX5Nk4ZCUqdqy4telkH/OBLwttyudICwuv3Saw 9ZjXoZ1tTPNUr4ge4n7fk7nldlb9HnMlluKMREMt5qLiRABJZBioaQIAAA== X-CMS-MailID: 20180312140620epcas1p10db98576017a2e4ef9a6ada74eb5daf0 X-Msg-Generator: CA CMS-TYPE: 101P X-CMS-RootMailID: 20180312140620epcas1p10db98576017a2e4ef9a6ada74eb5daf0 X-RootMTR: 20180312140620epcas1p10db98576017a2e4ef9a6ada74eb5daf0 References: <20180310064059.12720-1-jmoreira@suse.de> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594531866995400675?= X-GMAIL-MSGID: =?utf-8?q?1594741053566168916?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Hi, On Saturday, March 10, 2018 07:27:21 AM Kees Cook wrote: > On Fri, Mar 9, 2018 at 10:40 PM, Joao Moreira wrot= e: > > It is possible to indirectly invoke functions with prototypes that = do not > > match those of the respectively used function pointers by using voi= d types. > > Despite widely used as a feature for relaxing function invocation, = this > > should be avoided when possible as it may prevent the use of heuris= tics > > such as prototype matching-based Control-Flow Integrity, which can = be used > > to prevent ROP-based attacks. > > > > Given the above, the current efforts to improve the Linux security,= and the > > upcoming kernel support to compilers with CFI features, fix prototy= pes in > > vgacon console driver. > > > > Another similar fix can be seen in [1]. > > > > [1] https://android-review.googlesource.com/c/kernel/common/+/60201= 0 > > > > Signed-off-by: Jo=E3o Moreira >=20 > Whoops, I missed this one. :) Thanks! Greg, do you need this resent > directly to you? I would prefer for drivers/video/console/ changes to go through fbdev tree (like suggested by scripts/get_maintainers.pl).. However since Greg has already merged your CFI patches: Acked-by: Bartlomiej Zolnierkiewicz > Acked-by: Kees Cook >=20 > -Kees >=20 > > --- > > drivers/video/console/vgacon.c | 18 +++++++++++++----- > > 1 file changed, 13 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/video/console/vgacon.c b/drivers/video/console= /vgacon.c > > index a17ba1465815..f00b630f6839 100644 > > --- a/drivers/video/console/vgacon.c > > +++ b/drivers/video/console/vgacon.c > > @@ -1407,21 +1407,29 @@ static bool vgacon_scroll(struct vc_data *c= , unsigned int t, unsigned int b, > > * The console `switch' structure for the VGA based console > > */ > > > > -static int vgacon_dummy(struct vc_data *c) > > +static int vgacon_clear(struct vc_data *c) > > { > > return 0; > > } > > > > -#define DUMMY (void *) vgacon_dummy > > +static void vgacon_putc(struct vc_data *c, int a, int b, int d) > > +{ > > + return; > > +} > > + > > +static void vgacon_putcs(struct vc_data *c, ushort *s, int a, int = b, int d) > > +{ > > + return; > > +} > > > > const struct consw vga_con =3D { > > .owner =3D THIS_MODULE, > > .con_startup =3D vgacon_startup, > > .con_init =3D vgacon_init, > > .con_deinit =3D vgacon_deinit, > > - .con_clear =3D DUMMY, > > - .con_putc =3D DUMMY, > > - .con_putcs =3D DUMMY, > > + .con_clear =3D vgacon_clear, > > + .con_putc =3D vgacon_putc, > > + .con_putcs =3D vgacon_putcs, > > .con_cursor =3D vgacon_cursor, > > .con_scroll =3D vgacon_scroll, > > .con_switch =3D vgacon_switch, > > -- > > 2.13.6 Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bartlomiej Zolnierkiewicz Date: Mon, 12 Mar 2018 14:06:12 +0000 Subject: Re: [PATCH] vgacon: fix function prototypes Message-Id: <4831767.IeJWIvYDSU@amdc3058> List-Id: References: <20180310064059.12720-1-jmoreira@suse.de> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: Kees Cook Cc: Joao Moreira , Greg KH , Kernel Hardening , LKML , Daniel Micay , linux-fbdev@vger.kernel.org Hi, On Saturday, March 10, 2018 07:27:21 AM Kees Cook wrote: > On Fri, Mar 9, 2018 at 10:40 PM, Joao Moreira wrote: > > It is possible to indirectly invoke functions with prototypes that do n= ot > > match those of the respectively used function pointers by using void ty= pes. > > Despite widely used as a feature for relaxing function invocation, this > > should be avoided when possible as it may prevent the use of heuristics > > such as prototype matching-based Control-Flow Integrity, which can be u= sed > > to prevent ROP-based attacks. > > > > Given the above, the current efforts to improve the Linux security, and= the > > upcoming kernel support to compilers with CFI features, fix prototypes = in > > vgacon console driver. > > > > Another similar fix can be seen in [1]. > > > > [1] https://android-review.googlesource.com/c/kernel/common/+/602010 > > > > Signed-off-by: Jo=E3o Moreira >=20 > Whoops, I missed this one. :) Thanks! Greg, do you need this resent > directly to you? I would prefer for drivers/video/console/ changes to go through fbdev tree (like suggested by scripts/get_maintainers.pl).. However since Greg has already merged your CFI patches: Acked-by: Bartlomiej Zolnierkiewicz > Acked-by: Kees Cook >=20 > -Kees >=20 > > --- > > drivers/video/console/vgacon.c | 18 +++++++++++++----- > > 1 file changed, 13 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vga= con.c > > index a17ba1465815..f00b630f6839 100644 > > --- a/drivers/video/console/vgacon.c > > +++ b/drivers/video/console/vgacon.c > > @@ -1407,21 +1407,29 @@ static bool vgacon_scroll(struct vc_data *c, un= signed int t, unsigned int b, > > * The console `switch' structure for the VGA based console > > */ > > > > -static int vgacon_dummy(struct vc_data *c) > > +static int vgacon_clear(struct vc_data *c) > > { > > return 0; > > } > > > > -#define DUMMY (void *) vgacon_dummy > > +static void vgacon_putc(struct vc_data *c, int a, int b, int d) > > +{ > > + return; > > +} > > + > > +static void vgacon_putcs(struct vc_data *c, ushort *s, int a, int b, i= nt d) > > +{ > > + return; > > +} > > > > const struct consw vga_con =3D { > > .owner =3D THIS_MODULE, > > .con_startup =3D vgacon_startup, > > .con_init =3D vgacon_init, > > .con_deinit =3D vgacon_deinit, > > - .con_clear =3D DUMMY, > > - .con_putc =3D DUMMY, > > - .con_putcs =3D DUMMY, > > + .con_clear =3D vgacon_clear, > > + .con_putc =3D vgacon_putc, > > + .con_putcs =3D vgacon_putcs, > > .con_cursor =3D vgacon_cursor, > > .con_scroll =3D vgacon_scroll, > > .con_switch =3D vgacon_switch, > > -- > > 2.13.6 Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics