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authorGustavo A. R. Silva <gustavo@embeddedor.com>2018-08-16 22:30:38 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-09-18 15:51:30 +0200
commite97267cb4d1ee01ca0929638ec0fcbb0904f903d (patch)
tree33978ca9804f54d40f9e00d6fc8c81f4c8a52d25 /drivers/tty/vt
parenttty: Drop tty->count on tty_reopen() failure (diff)
downloadlinux-e97267cb4d1ee01ca0929638ec0fcbb0904f903d.tar.xz
linux-e97267cb4d1ee01ca0929638ec0fcbb0904f903d.zip
tty: vt_ioctl: fix potential Spectre v1
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>
Diffstat (limited to 'drivers/tty/vt')
-rw-r--r--drivers/tty/vt/vt_ioctl.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index a78ad10a119b..73cdc0d633dd 100644
--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -32,6 +32,8 @@
#include <asm/io.h>
#include <linux/uaccess.h>
+#include <linux/nospec.h>
+
#include <linux/kbd_kern.h>
#include <linux/vt_kern.h>
#include <linux/kbd_diacr.h>
@@ -700,6 +702,8 @@ 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);