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| author |   Gustavo A. R. Silva <gustavo@embeddedor.com> | 2018-08-16 15:30:38 -0500 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-09-18 15:51:30 +0200 |
| commit | e97267cb4d1ee01ca0929638ec0fcbb0904f903d (patch) | |
| tree | 33978ca9804f54d40f9e00d6fc8c81f4c8a52d25 /drivers/tty/vt | |
| parent | tty: Drop tty->count on tty_reopen() failure (diff) | |
| download | linux-dev-e97267cb4d1ee01ca0929638ec0fcbb0904f903d.tar.xz linux-dev-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.c | 4 |
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); |