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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	Alan Cox <alan@linux.intel.com>
Subject: [PATCH 4.4 19/28] tty: vt_ioctl: fix potential Spectre v1
Date: Thu, 27 Sep 2018 11:06:43 +0200	[thread overview]
Message-ID: <20180927090638.488067328@linuxfoundation.org> (raw)
In-Reply-To: <20180927090637.687829444@linuxfoundation.org>

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

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

From: Gustavo A. R. Silva <gustavo@embeddedor.com>

commit e97267cb4d1ee01ca0929638ec0fcbb0904f903d upstream.

vsa.console is indirectly controlled by user-space, hence leading to
a potential exploitation of the Spectre variant 1 vulnerability.

This issue was detected with the help of Smatch:

drivers/tty/vt/vt_ioctl.c:711 vt_ioctl() warn: potential spectre issue
'vc_cons' [r]

Fix this by sanitizing vsa.console before using it to index vc_cons

Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -31,6 +31,8 @@
 #include <asm/io.h>
 #include <asm/uaccess.h>
 
+#include <linux/nospec.h>
+
 #include <linux/kbd_kern.h>
 #include <linux/vt_kern.h>
 #include <linux/kbd_diacr.h>
@@ -703,6 +705,8 @@ int vt_ioctl(struct tty_struct *tty,
 		if (vsa.console == 0 || vsa.console > MAX_NR_CONSOLES)
 			ret = -ENXIO;
 		else {
+			vsa.console = array_index_nospec(vsa.console,
+							 MAX_NR_CONSOLES + 1);
 			vsa.console--;
 			console_lock();
 			ret = vc_allocate(vsa.console);



  parent reply	other threads:[~2018-09-27  9:33 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-27  9:06 [PATCH 4.4 00/28] 4.4.159-stable review Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 01/28] NFC: Fix possible memory corruption when handling SHDLC I-Frame commands Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 02/28] NFC: Fix the number of pipes Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 03/28] ASoC: cs4265: fix MMTLR Data switch control Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 04/28] ALSA: bebob: use address returned by kmalloc() instead of kernel stack for streaming DMA mapping Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 05/28] ALSA: emu10k1: fix possible info leak to userspace on SNDRV_EMU10K1_IOCTL_INFO Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 06/28] platform/x86: alienware-wmi: Correct a memory leak Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 07/28] xen/netfront: dont bug in case of too many frags Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 08/28] xen/x86/vpmu: Zero struct pt_regs before calling into sample handling code Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 09/28] ring-buffer: Allow for rescheduling when removing pages Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 10/28] mm: shmem.c: Correctly annotate new inodes for lockdep Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 11/28] gso_segment: Reset skb->mac_len after modifying network header Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 12/28] ipv6: fix possible use-after-free in ip6_xmit() Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 13/28] net/appletalk: fix minor pointer leak to userspace in SIOCFINDIPDDPRT Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 14/28] net: hp100: fix always-true check for link up state Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 15/28] neighbour: confirm neigh entries when ARP packet is received Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 16/28] scsi: target: iscsi: Use hex2bin instead of a re-implementation Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 17/28] ocfs2: fix ocfs2 read block panic Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 18/28] drm/nouveau/drm/nouveau: Use pm_runtime_get_noresume() in connector_detect() Greg Kroah-Hartman
2018-09-27  9:06 ` Greg Kroah-Hartman [this message]
2018-09-27  9:06 ` [PATCH 4.4 20/28] ext4: avoid divide by zero fault when deleting corrupted inline directories Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 21/28] ext4: recalucate superblock checksum after updating free blocks/inodes Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 22/28] ext4: fix online resizes handling of a too-small final block group Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 23/28] ext4: fix online resizing for bigalloc file systems with a 1k block size Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 24/28] ext4: dont mark mmp buffer head dirty Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 25/28] arm64: Add trace_hardirqs_off annotation in ret_to_user Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 26/28] HID: sony: Update device ids Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 27/28] HID: sony: Support DS4 dongle Greg Kroah-Hartman
2018-09-27  9:06 ` [PATCH 4.4 28/28] iw_cxgb4: only allow 1 flush on user qps Greg Kroah-Hartman
2018-09-27 18:58 ` [PATCH 4.4 00/28] 4.4.159-stable review Nathan Chancellor
2018-09-27 19:47 ` Rafael David Tinoco
2018-09-27 20:19 ` Shuah Khan
2018-09-27 23:05 ` Guenter Roeck

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