From: Jakob Koschel <jakobkoschel@gmail.com> stable inclusion from stable-v5.10.101 commit 778302ca09498b448620edd372dc908bebf80bdf bugzilla: https://gitee.com/openeuler/kernel/issues/I5669Z Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 61cc70d9e8ef5b042d4ed87994d20100ec8896d9 upstream. array_index_nospec ensures that an out-of-bounds value is set to zero on the transient path. Decreasing the value by one afterwards causes a transient integer underflow. vsa.console should be decreased first and then sanitized with array_index_nospec. Kasper Acknowledgements: Jakob Koschel, Brian Johannesmeyer, Kaveh Razavi, Herbert Bos, Cristiano Giuffrida from the VUSec group at VU Amsterdam. Co-developed-by: Brian Johannesmeyer <bjohannesmeyer@gmail.com> Signed-off-by: Brian Johannesmeyer <bjohannesmeyer@gmail.com> Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com> Link: https://lore.kernel.org/r/20220127144406.3589293-1-jakobkoschel@gmail.com Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yu Liao <liaoyu15@huawei.com> Reviewed-by: Wei Li <liwei391@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- drivers/tty/vt/vt_ioctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c index 90e4fcd3dc39..1e627ecab6af 100644 --- a/drivers/tty/vt/vt_ioctl.c +++ b/drivers/tty/vt/vt_ioctl.c @@ -699,8 +699,8 @@ static int vt_setactivate(struct vt_setactivate __user *sa) if (vsa.console == 0 || vsa.console > MAX_NR_CONSOLES) return -ENXIO; - vsa.console = array_index_nospec(vsa.console, MAX_NR_CONSOLES + 1); vsa.console--; + vsa.console = array_index_nospec(vsa.console, MAX_NR_CONSOLES); console_lock(); ret = vc_allocate(vsa.console); if (ret) { -- 2.20.1