From: Jakob Koschel jakobkoschel@gmail.com

stable inclusion from stable-v4.19.230 commit 170325aba4608bde3e7d21c9c19b7bc266ac0885 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IADG0Z CVE: CVE-2022-48804

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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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: Cai Xinchen caixinchen1@huawei.com --- drivers/tty/vt/vt_ioctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c index 915b0173b4f8..9a1ede70f403 100644 --- a/drivers/tty/vt/vt_ioctl.c +++ b/drivers/tty/vt/vt_ioctl.c @@ -673,9 +673,9 @@ 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--; + vsa.console = array_index_nospec(vsa.console, + MAX_NR_CONSOLES); console_lock(); ret = vc_allocate(vsa.console); if (ret == 0) {