在 2022/7/31 20:37, Greg KH 写道: > On Fri, Jul 29, 2022 at 03:11:38AM +0000, Chen Jun wrote: >> refer to https://lore.kernel.org/all/20220706150253.2186-1-deller@xxxxxx/ >> 3 patches are provided to fix CVE-2021-3365 (When sending malicous data >> to kernel by ioctl cmd FBIOPUT_VSCREENINFO,kernel will write memory out >> of bounds. https://nvd.nist.gov/vuln/detail/CVE-2021-33655) in mainline. >> >> But only >> commit 65a01e601dbb ("fbcon: Disallow setting font bigger than screen size") >> was backported to stable (4.19,4.14). >> >> without other two commit >> commit e64242caef18 ("fbcon: Prevent that screen size is smaller than font size") >> commit 6c11df58fd1a ("fbmem: Check virtual screen sizes in fb_set_var()") >> The problem still exists. >> >> static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, unsigned long arg) >> fb_set_var(info, &var); >> fb_notifier_call_chain(evnt, &event); // evnt = FB_EVENT_MODE_CHANGE >> >> static int fbcon_event_notify(struct notifier_block *self, >> unsigned long action, void *data) >> fbcon_modechanged(info); >> updatescrollmode(p, info, vc); >> ... >> p->vrows = vyres/fh; >> if (yres > (fh * (vc->vc_rows + 1))) >> p->vrows -= (yres - (fh * vc->vc_rows)) / fh; >> if ((yres % fh) && (vyres % fh < yres % fh)) >> p->vrows--; [1] >> [1]: p->vrows could be -1, like what CVE-2021-3365 described. >> >> I think, the two commits should be backported to 4.19 and 4.14. >> >> Helge Deller (2): >> fbcon: Prevent that screen size is smaller than font size >> fbmem: Check virtual screen sizes in fb_set_var() >> >> drivers/video/fbdev/core/fbcon.c | 28 ++++++++++++++++++++++++++++ >> drivers/video/fbdev/core/fbmem.c | 20 +++++++++++++++++--- >> include/linux/fbcon.h | 4 ++++ >> 3 files changed, 49 insertions(+), 3 deletions(-) >> >> -- >> 2.17.1 >> > > This breaks the build on 4.14.y, did you test it there? > > The error is: > ERROR: "is_console_locked" [drivers/video/fbdev/core/fb.ko] undefined! > if CONFIG_FRAMEBUFFER_CONSOLE = M, "d48de54a9dab printk: Export is_console_locked" is needed, which merged in 4.19. I will sent the patch. > Can you please fix this up and also do a 4.9.y version? > ok, I will do it. > thanks, > > greg k-h > -- Regards Chen Jun
