kernel.git/drivers/video/fbdev/core, branch linux-5.12.y

fbmem: Do not delete the mode that is still in use

2021-07-20T14:02:01Z

commit 0af778269a522c988ef0b4188556aba97fb420cc upstream. The execution of fb_delete_videomode() is not based on the result of the previous fbcon_mode_deleted(). As a result, the mode is directly deleted, regardless of whether it is still in use, which may cause UAF. ================================================================== BUG: KASAN: use-after-free in fb_mode_is_equal+0x36e/0x5e0 \ drivers/video/fbdev/core/modedb.c:924 Read of size 4 at addr ffff88807e0ddb1c by task syz-executor.0/18962 CPU: 2 PID: 18962 Comm: syz-executor.0 Not tainted 5.10.45-rc1+ #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ... Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x137/0x1be lib/dump_stack.c:118 print_address_description+0x6c/0x640 mm/kasan/report.c:385 __kasan_report mm/kasan/report.c:545 [inline] kasan_report+0x13d/0x1e0 mm/kasan/report.c:562 fb_mode_is_equal+0x36e/0x5e0 drivers/video/fbdev/core/modedb.c:924 fbcon_mode_deleted+0x16a/0x220 drivers/video/fbdev/core/fbcon.c:2746 fb_set_var+0x1e1/0xdb0 drivers/video/fbdev/core/fbmem.c:975 do_fb_ioctl+0x4d9/0x6e0 drivers/video/fbdev/core/fbmem.c:1108 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 18960: kasan_save_stack mm/kasan/common.c:48 [inline] kasan_set_track+0x3d/0x70 mm/kasan/common.c:56 kasan_set_free_info+0x17/0x30 mm/kasan/generic.c:355 __kasan_slab_free+0x108/0x140 mm/kasan/common.c:422 slab_free_hook mm/slub.c:1541 [inline] slab_free_freelist_hook+0xd6/0x1a0 mm/slub.c:1574 slab_free mm/slub.c:3139 [inline] kfree+0xca/0x3d0 mm/slub.c:4121 fb_delete_videomode+0x56a/0x820 drivers/video/fbdev/core/modedb.c:1104 fb_set_var+0x1f3/0xdb0 drivers/video/fbdev/core/fbmem.c:978 do_fb_ioctl+0x4d9/0x6e0 drivers/video/fbdev/core/fbmem.c:1108 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fixes: 13ff178ccd6d ("fbcon: Call fbcon_mode_deleted/new_modelist directly") Signed-off-by: Zhen Lei Cc: # v5.3+ Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20210712085544.2828-1-thunder.leizhen@huawei.com Signed-off-by: Greg Kroah-Hartman

tty: vt: always invoke vc->vc_sw->con_resize callback

2021-05-26T10:59:14Z

commit ffb324e6f874121f7dce5bdae5e05d02baae7269 upstream. syzbot is reporting OOB write at vga16fb_imageblit() [1], for resize_screen() from ioctl(VT_RESIZE) returns 0 without checking whether requested rows/columns fit the amount of memory reserved for the graphical screen if current mode is KD_GRAPHICS. ---------- #include #include #include #include #include #include int main(int argc, char *argv[]) { const int fd = open("/dev/char/4:1", O_RDWR); struct vt_sizes vt = { 0x4100, 2 }; ioctl(fd, KDSETMODE, KD_GRAPHICS); ioctl(fd, VT_RESIZE, &vt); ioctl(fd, KDSETMODE, KD_TEXT); return 0; } ---------- Allow framebuffer drivers to return -EINVAL, by moving vc->vc_mode != KD_GRAPHICS check from resize_screen() to fbcon_resize(). Link: https://syzkaller.appspot.com/bug?extid=1f29e126cf461c4de3b3 [1] Reported-by: syzbot Suggested-by: Linus Torvalds Signed-off-by: Tetsuo Handa Tested-by: syzbot Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

fbdev: zero-fill colormap in fbcmap.c

2021-05-12T06:39:33Z

commit 19ab233989d0f7ab1de19a036e247afa4a0a1e9c upstream. Use kzalloc() rather than kmalloc() for the dynamically allocated parts of the colormap in fb_alloc_cmap_gfp, to prevent a leak of random kernel data to userspace under certain circumstances. Fixes a KMSAN-found infoleak bug reported by syzbot at: https://syzkaller.appspot.com/bug?id=741578659feabd108ad9e06696f0c1f2e69c4b6e Reported-by: syzbot+47fa9c9c648b765305b9@syzkaller.appspotmail.com Cc: stable Reviewed-by: Geert Uytterhoeven Signed-off-by: Phillip Potter Link: https://lore.kernel.org/r/20210331220719.1499743-1-phil@philpotter.co.uk Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman

drivers: video: fbcon: fix NULL dereference in fbcon_cursor()

2021-03-23T14:15:17Z

add null-check on function pointer before dereference on ops->cursor Reported-by: syzbot+b67aaae8d3a927f68d20@syzkaller.appspotmail.com Cc: stable Signed-off-by: Du Cheng Link: https://lore.kernel.org/r/20210312081421.452405-1-ducheng2@gmail.com Signed-off-by: Greg Kroah-Hartman

video: fbdev: core: Fix kernel-doc warnings in fbmon + fb_notify

2020-12-08T17:31:56Z

Fix kernel-doc warnings reported when using W=1 v2: - Improve subject (Lee) v3: - Add RETURNS documentation (Thomas) v4: - Use Return: not RETURNS (Randy) Signed-off-by: Sam Ravnborg Acked-by: Randy Dunlap Cc: Lee Jones Cc: Sam Ravnborg Cc: Randy Dunlap Cc: Bartlomiej Zolnierkiewicz Cc: Daniel Vetter Cc: "Alexander A. Klimov" Link: https://patchwork.freedesktop.org/patch/msgid/20201206205132.GA1869030@ravnborg.org

video: fbcon: Fix warnings by using pr_debug() in fbcon

2020-11-29T21:44:48Z

Replacing DPRINTK() statements with pr_debug fixes set but not used warnings. And moves to a more standard logging setup at the same time. v2: - Fix indent (Joe) Signed-off-by: Sam Ravnborg Acked-by: Thomas Zimmermann Cc: Joe Perches Cc: Greg Kroah-Hartman Cc: Daniel Vetter Cc: Bartlomiej Zolnierkiewicz Cc: Sam Ravnborg Cc: Jiri Slaby Cc: Peilin Ye Cc: Tetsuo Handa Cc: George Kennedy Cc: Nathan Chancellor Cc: Peter Rosin Link: https://patchwork.freedesktop.org/patch/msgid/20201128224114.1033617-3-sam@ravnborg.org

fbcon: Drop EXPORT_SYMBOL

2020-11-17T10:00:43Z

Every since commit 6104c37094e729f3d4ce65797002112735d49cd1 Author: Daniel Vetter Date: Tue Aug 1 17:32:07 2017 +0200 fbcon: Make fbcon a built-time depency for fbdev these are no longer distinct loadable modules, so exporting symbols is kinda pointless. Acked-by: Thomas Zimmermann Signed-off-by: Daniel Vetter Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: Daniel Vetter Cc: Tetsuo Handa Cc: Helge Deller Cc: Peilin Ye Link: https://patchwork.freedesktop.org/patch/msgid/20201029101428.4058311-2-daniel.vetter@ffwll.ch

fbcon: Disable accelerated scrolling

2020-11-17T10:00:29Z

So ever since syzbot discovered fbcon, we have solid proof that it's full of bugs. And often the solution is to just delete code and remove features, e.g. 50145474f6ef ("fbcon: remove soft scrollback code"). Now the problem is that most modern-ish drivers really only treat fbcon as an dumb kernel console until userspace takes over, and Oops printer for some emergencies. Looking at drm drivers and the basic vesa/efi fbdev drivers shows that only 3 drivers support any kind of acceleration: - nouveau, seems to be enabled by default - omapdrm, when a DMM remapper exists using remapper rewriting for y/xpanning - gma500, but that is getting deleted now for the GTT remapper trick, and the accelerated copyarea never set the FBINFO_HWACCEL_COPYAREA flag, so unused (and could be deleted already I think). No other driver supportes accelerated fbcon. And fbcon is the only user of this accel code (it's not exposed as uapi through ioctls), which means we could garbage collect fairly enormous amounts of code if we kill this. Plus because syzbot only runs on virtual hardware, and none of the drivers for that have acceleration, we'd remove a huge gap in testing. And there's no other even remotely comprehensive testing aside from syzbot. This patch here just disables the acceleration code by always redrawing when scrolling. The plan is that once this has been merged for well over a year in released kernels, we can start to go around and delete a lot of code. v2: - Drop a few more unused local variables, somehow I missed the compiler warnings (Sam) - Fix typo in comment (Jiri) - add a todo entry for the cleanup (Thomas) v3: Remove more unused variables (0day) Reviewed-by: Tomi Valkeinen Reviewed-by: Thomas Zimmermann Reviewed-by: Greg Kroah-Hartman Acked-by: Sam Ravnborg Cc: Jiri Slaby Cc: Bartlomiej Zolnierkiewicz Cc: Greg Kroah-Hartman Cc: Linus Torvalds Cc: Ben Skeggs Cc: nouveau@lists.freedesktop.org Cc: Tomi Valkeinen Cc: Daniel Vetter Cc: Jiri Slaby Cc: "Gustavo A. R. Silva" Cc: Tetsuo Handa Cc: Peilin Ye Cc: George Kennedy Cc: Nathan Chancellor Cc: Peter Rosin Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20201029132229.4068359-1-daniel.vetter@ffwll.ch

video: fix some kernel-doc markups

2020-11-16T17:23:16Z

Some identifiers have different names between their prototypes and the kernel-doc markup. Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/21661aed9892a1bacc7ef76a5dc9f5c7b37f5d8f.1605521731.git.mchehab+huawei@kernel.org

fbcon: Avoid using FNTCHARCNT() and hard-coded built-in font charcount

2020-11-16T15:33:12Z

For user-provided fonts, the framebuffer layer is using a magic negative-indexing macro, FNTCHARCNT(), to keep track of their number of characters: #define FNTCHARCNT(fd) (((int *)(fd))[-3]) For built-in fonts, it is using hard-coded values (256). This results in something like the following: map.length = (ops->p->userfont) ? FNTCHARCNT(ops->p->fontdata) : 256; This is unsatisfactory. In fact, there is already a `charcount` field in our virtual console descriptor (see `struct console_font` inside `struct vc_data`), let us use it: map.length = vc->vc_font.charcount; Recently we added a `charcount` field to `struct font_desc`. Use it to set `vc->vc_font.charcount` properly. The idea is: - We only use FNTCHARCNT() on `vc->vc_font.data` and `p->fontdata`. Assume FNTCHARCNT() is working as intended; - Whenever `vc->vc_font.data` is set, also set `vc->vc_font.charcount` properly; - We can now replace `FNTCHARCNT(vc->vc_font.data)` with `vc->vc_font.charcount`; - Since `p->fontdata` always point to the same font data buffer with `vc->vc_font.data`, we can also replace `FNTCHARCNT(p->fontdata)` with `vc->vc_font.charcount`. In conclusion, set `vc->vc_font.charcount` properly in fbcon_startup(), fbcon_init(), fbcon_set_disp() and fbcon_do_set_font(), then replace FNTCHARCNT() with `vc->vc_font.charcount`. No more if-else between negative-indexing macros and hard-coded values. Do not include in fbcon_rotate.c and tileblit.c, since they no longer need it. Depends on patch "Fonts: Add charcount field to font_desc". Suggested-by: Daniel Vetter Signed-off-by: Peilin Ye Reviewed-by: Greg Kroah-Hartman Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/e460a5780e54e3022661d5f09555144583b4cc59.1605169912.git.yepeilin.cs@gmail.com