linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	syzbot+17a8efdf800000@syzkaller.appspotmail.com,
	Alexander Potapenko <glider@google.com>
Subject: [PATCH 4.17 16/46] vt: prevent leaking uninitialized data to userspace via /dev/vcs*
Date: Fri,  6 Jul 2018 07:46:37 +0200	[thread overview]
Message-ID: <20180706054525.376507928@linuxfoundation.org> (raw)
In-Reply-To: <20180706054524.595521988@linuxfoundation.org>

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alexander Potapenko <glider@google.com>

commit 21eff69aaaa0e766ca0ce445b477698dc6a9f55a upstream.

KMSAN reported an infoleak when reading from /dev/vcs*:

  BUG: KMSAN: kernel-infoleak in vcs_read+0x18ba/0x1cc0
  Call Trace:
  ...
   kmsan_copy_to_user+0x7a/0x160 mm/kmsan/kmsan.c:1253
   copy_to_user ./include/linux/uaccess.h:184
   vcs_read+0x18ba/0x1cc0 drivers/tty/vt/vc_screen.c:352
   __vfs_read+0x1b2/0x9d0 fs/read_write.c:416
   vfs_read+0x36c/0x6b0 fs/read_write.c:452
  ...
  Uninit was created at:
   kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279
   kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:189
   kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:315
   __kmalloc+0x13a/0x350 mm/slub.c:3818
   kmalloc ./include/linux/slab.h:517
   vc_allocate+0x438/0x800 drivers/tty/vt/vt.c:787
   con_install+0x8c/0x640 drivers/tty/vt/vt.c:2880
   tty_driver_install_tty drivers/tty/tty_io.c:1224
   tty_init_dev+0x1b5/0x1020 drivers/tty/tty_io.c:1324
   tty_open_by_driver drivers/tty/tty_io.c:1959
   tty_open+0x17b4/0x2ed0 drivers/tty/tty_io.c:2007
   chrdev_open+0xc25/0xd90 fs/char_dev.c:417
   do_dentry_open+0xccc/0x1440 fs/open.c:794
   vfs_open+0x1b6/0x2f0 fs/open.c:908
  ...
  Bytes 0-79 of 240 are uninitialized

Consistently allocating |vc_screenbuf| with kzalloc() fixes the problem

Reported-by: syzbot+17a8efdf800000@syzkaller.appspotmail.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/tty/vt/vt.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -784,7 +784,7 @@ int vc_allocate(unsigned int currcons)	/
 	if (!*vc->vc_uni_pagedir_loc)
 		con_set_default_unimap(vc);
 
-	vc->vc_screenbuf = kmalloc(vc->vc_screenbuf_size, GFP_KERNEL);
+	vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_KERNEL);
 	if (!vc->vc_screenbuf)
 		goto err_free;
 
@@ -871,7 +871,7 @@ static int vc_do_resize(struct tty_struc
 
 	if (new_screen_size > (4 << 20))
 		return -EINVAL;
-	newscreen = kmalloc(new_screen_size, GFP_USER);
+	newscreen = kzalloc(new_screen_size, GFP_USER);
 	if (!newscreen)
 		return -ENOMEM;
 



  parent reply	other threads:[~2018-07-06  5:49 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-06  5:46 [PATCH 4.17 00/46] 4.17.5-stable review Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 01/46] usb: cdc_acm: Add quirk for Uniden UBC125 scanner Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 02/46] USB: serial: cp210x: add CESINEL device ids Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 03/46] USB: serial: cp210x: add Silicon Labs IDs for Windows Update Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 04/46] usb: dwc2: fix the incorrect bitmaps for the ports of multi_tt hub Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 05/46] usb: typec: tcpm: fix logbuffer index is wrong if _tcpm_log is re-entered Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 06/46] acpi: Add helper for deactivating memory region Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 07/46] usb: typec: ucsi: acpi: Workaround for cache mode issue Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 08/46] usb: typec: ucsi: Fix for incorrect status data issue Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 09/46] xhci: Fix kernel oops in trace_xhci_free_virt_device Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 10/46] n_tty: Fix stall at n_tty_receive_char_special() Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 11/46] n_tty: Access echo_* variables carefully Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 12/46] staging: android: ion: Return an ERR_PTR in ion_map_kernel Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 13/46] iio: mma8452: Fix ignoring MMA8452_INT_DRDY Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 14/46] serial: 8250_pci: Remove stalled entries in blacklist Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 15/46] serdev: fix memleak on module unload Greg Kroah-Hartman
2018-07-06  5:46 ` Greg Kroah-Hartman [this message]
2018-07-06  5:49   ` [PATCH 4.17 16/46] vt: prevent leaking uninitialized data to userspace via /dev/vcs* syzbot
2018-07-06  5:46 ` [PATCH 4.17 22/46] drm/sti: Depend on OF rather than selecting it Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 23/46] drm/amd/display: Clear connectors edid pointer Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 25/46] drm/qxl: Call qxl_bo_unref outside atomic context Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 26/46] drm/atmel-hlcdc: check stride values in the first plane Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 27/46] Revert "drm/sun4i: Handle DRM_BUS_FLAG_PIXDATA_*EDGE" Greg Kroah-Hartman
2018-07-06  5:46 ` [PATCH 4.17 28/46] drm/amdgpu: Dont default to DC support for Kaveri and older Greg Kroah-Hartman
2018-07-06  5:47 ` [PATCH 4.17 40/46] drm/i915: Enable provoking vertex fix on Gen9 systems Greg Kroah-Hartman
2018-07-06  5:47 ` [PATCH 4.17 41/46] netfilter: ip6t_rpfilter: provide input interface for route lookup Greg Kroah-Hartman
2018-07-06  5:47 ` [PATCH 4.17 42/46] netfilter: xt_connmark: fix list corruption on rmmod Greg Kroah-Hartman
2018-07-06  5:47 ` [PATCH 4.17 43/46] netfilter: nf_tables: use WARN_ON_ONCE instead of BUG_ON in nft_do_chain() Greg Kroah-Hartman
2018-07-06  5:47 ` [PATCH 4.17 44/46] ARM64: dts: meson-gxl-s905x-p212: Add phy-supply for usb0 Greg Kroah-Hartman
2018-07-06  5:47 ` [PATCH 4.17 45/46] x86/mm: Dont free P4D table when it is folded at runtime Greg Kroah-Hartman
2018-07-06  5:47 ` [PATCH 4.17 46/46] ARM: dts: imx6q: Use correct SDMA script for SPI5 core Greg Kroah-Hartman
2018-07-06 17:51 ` [PATCH 4.17 00/46] 4.17.5-stable review Dan Rue
2018-07-06 18:09   ` Dan Rue
2018-07-07 14:52   ` Greg Kroah-Hartman
2018-07-07 21:40 ` Guenter Roeck

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180706054525.376507928@linuxfoundation.org \
    --to=gregkh@linuxfoundation.org \
    --cc=glider@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=stable@vger.kernel.org \
    --cc=syzbot+17a8efdf800000@syzkaller.appspotmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).