diff options
| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2018-08-16 15:30:38 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-09-29 03:08:53 -0700 |
| commit | 1aa698b65186c13ed775896ed1dfec7c26c73d60 (patch) | |
| tree | 6313ff0915898b7ff0bd8ce0603ff765f66d27bf | |
| parent | 64436716c3a538ed65413c5257c6176dae5d807c (diff) | |
tty: vt_ioctl: fix potential Spectre v1
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>
| -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 97d5a74558a3..a86bc7afb3b2 100644 --- 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); |