On Wed, Jan 29, 2020 at 3:59 PM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > > On Wed, Jan 29, 2020 at 3:40 PM Sergey Senozhatsky > <sergey.senozhatsky@xxxxxxxxx> wrote: > > > > Cc-ing Dmitry and Tetsuo > > > > Original Message-id: CAA=061EoW8AmjUrBLsJy5nTDz-1jeArLeB+z6HJuyZud0zZXug@xxxxxxxxxxxxxx > > > > On (20/01/29 23:17), Sergey Senozhatsky wrote: > > > > Hmm. There is something strange about it. I use vga console quite > > > > often, and scrolling happens all the time, yet I can't get the same > > > > out-of-bounds report (nor have I ever seen it in the past), even with > > > > the reproducer. Is it supposed to be executed as it is, or are there > > > > any preconditions? Any chance that something that runs prior to that > > > > reproducer somehow impacts the system? Just asking. > > > > > > These questions were addressed to anon anon (742991625abc@xxxxxxxxx), > > > not to Bartlomiej. > > > > Could this be GCC_PLUGIN related? > > syzkaller repros are meant to be self-contained, but they don't > capture the image and VM setup (or actual hardware). I suspect it may > have something to do with these bugs. > syzbot has reported a bunch of similar bugs in one of our internal kernels: > > KASAN: slab-out-of-bounds Read in vgacon_scroll > KASAN: slab-out-of-bounds Read in vgacon_invert_region > KASAN: use-after-free Write in vgacon_scroll > KASAN: use-after-free Read in vgacon_scroll > KASAN: use-after-free Read in vgacon_invert_region > BUG: unable to handle kernel paging request in vgacon_scroll > > But none on upstream kernels. That may be some difference in config? > I actually don't know what affects these things. When I tried to get > at least some coverage of that code in syzkaller I just understood > that relations between all these > tty/pty/ptmx/vt/pt/ldisc/vcs/vcsu/fb/con/dri/drm/etc are complex to > say the least... It would also be good to figure out how we can cover this on syzbot/upstream. Our upstream config is: $ grep VGA upstream-kasan.config CONFIG_VGA_ARB=y CONFIG_VGA_ARB_MAX_GPUS=16 # CONFIG_VGA_SWITCHEROO is not set CONFIG_FB_VGA16=y CONFIG_VGASTATE=y CONFIG_VGA_CONSOLE=y CONFIG_VGACON_SOFT_SCROLLBACK=y CONFIG_VGACON_SOFT_SCROLLBACK_SIZE=64 # CONFIG_VGACON_SOFT_SCROLLBACK_PERSISTENT_ENABLE_BY_DEFAULT is not set CONFIG_LOGO_LINUX_VGA16=y # CONFIG_USB_SISUSBVGA is not set # CONFIG_VFIO_PCI_VGA is not set where anon's is: CONFIG_VGA_ARB=y CONFIG_VGA_ARB_MAX_GPUS=16 # CONFIG_VGA_SWITCHEROO is not set # CONFIG_FB_VGA16 is not set CONFIG_VGA_CONSOLE=y CONFIG_VGACON_SOFT_SCROLLBACK=y CONFIG_VGACON_SOFT_SCROLLBACK_SIZE=64 # CONFIG_VGACON_SOFT_SCROLLBACK_PERSISTENT_ENABLE_BY_DEFAULT is not set # CONFIG_LOGO_LINUX_VGA16 is not set # CONFIG_USB_SISUSBVGA is not set And the one on which are catching the bugs in vgacon on internal kernel is: CONFIG_VGA_ARB=y CONFIG_VGA_ARB_MAX_GPUS=16 # CONFIG_VGA_SWITCHEROO is not set # CONFIG_VGASTATE is not set CONFIG_VGA_CONSOLE=y # CONFIG_VGACON_SOFT_SCROLLBACK is not set # CONFIG_USB_SISUSBVGA is not set # CONFIG_VFIO_PCI_VGA is not set May it be related to CONFIG_VGASTATE? _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
