From: George Kennedy george.kennedy@oracle.com
stable inclusion from linux-4.19.143 commit 1221d11e5c35db18323ade3d4b2130bde89cc9df
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commit bc5269ca765057a1b762e79a1cfd267cd7bf1c46 upstream.
vc_resize() can return with an error after failure. Change VT_RESIZEX ioctl to save struct vc_data values that are modified and restore the original values in case of error.
Signed-off-by: George Kennedy george.kennedy@oracle.com Cc: stable stable@vger.kernel.org Reported-by: syzbot+38a3699c7eaf165b97a6@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/1596213192-6635-2-git-send-email-george.kennedy@or... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/tty/vt/vt_ioctl.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c index 5de81431c835..6a82030cf1ef 100644 --- a/drivers/tty/vt/vt_ioctl.c +++ b/drivers/tty/vt/vt_ioctl.c @@ -893,12 +893,22 @@ int vt_ioctl(struct tty_struct *tty, console_lock(); vcp = vc_cons[i].d; if (vcp) { + int ret; + int save_scan_lines = vcp->vc_scan_lines; + int save_font_height = vcp->vc_font.height; + if (v.v_vlin) vcp->vc_scan_lines = v.v_vlin; if (v.v_clin) vcp->vc_font.height = v.v_clin; vcp->vc_resize_user = 1; - vc_resize(vcp, v.v_cols, v.v_rows); + ret = vc_resize(vcp, v.v_cols, v.v_rows); + if (ret) { + vcp->vc_scan_lines = save_scan_lines; + vcp->vc_font.height = save_font_height; + console_unlock(); + return ret; + } } console_unlock(); }