linux-stable.git/drivers/video/fbdev, branch v7.2.4

fbdev: uvesafb: unregister connector callback on init failure

2026-09-07T15:36:53+00:00

commit de8db23aa7c337e606fca9faf48b3ba72968597a upstream.

uvesafb_init() registers the v86d connector callback before registering
the platform driver. If platform_driver_register() fails, the function
returns the error directly and leaves the connector callback registered.

The later platform-device failure path already unregisters the callback.
Add the same cleanup before the final return when platform-driver
registration fails.

This issue was identified during our ongoing static-analysis research while
reviewing kernel code.

Fixes: 8bdb3a2d7df4 ("uvesafb: the driver core")
Cc: stable@vger.kernel.org
Co-developed-by: Ijae Kim 
Signed-off-by: Ijae Kim 
Signed-off-by: Myeonghun Pak 
Signed-off-by: Helge Deller 
Signed-off-by: Greg Kroah-Hartman

fbdev: ssd1307fb: defer I2C transfers from damage callbacks

2026-09-07T15:36:53+00:00

commit 9ad709afdfa32509ed64938a6d9cd00db3cd54c2 upstream.

The fbdev damage callbacks may run from fbcon while printk has disabled
preemption.  They currently update the display synchronously, which enters
the sleeping I2C transfer path from atomic context.

A complete report from an RK3566 system follows:

  [  258.129004] watchdog: watchdog0: watchdog did not stop!
  [  258.129067] BUG: scheduling while atomic: systemd/1/0x00000003
  [  258.129076] Modules linked in: algif_hash algif_skcipher af_alg bnep
  binfmt_misc lz4hc lz4 zram snd_soc_hdmi_codec brcmfmac_wcc hci_uart
  fb_ssd1306(C) fbtft(C) btqca btrtl btintel btsdio snd_soc_simple_card
  motorcomm pwm_fan snd_soc_simple_card_utils ssd130x_spi nls_iso8859_1
  ssd130x btbcm drm_shmem_helper display_connector brcmfmac ssd1307fb
  brcmutil bluetooth cfg80211 rfkill snd_soc_rockchip_i2s_tdm
  snd_soc_rk817 hantro_vpu snd_soc_core snd_compress snd_pcm_dmaengine
  v4l2_vp9 snd_pcm v4l2_h264 rockchip_rga snd_timer rk_crypto2
  spi_rockchip_sfc videobuf2_dma_contig snd sm3_generic v4l2_mem2mem
  videobuf2_dma_sg dwmac_rk sm3 soundcore videobuf2_memops videobuf2_v4l2
  stmmac_platform dw_hdmi_cec videodev videobuf2_common dw_hdmi_i2s_audio
  stmmac rk817_charger pcs_xpcs mc cpufreq_dt sch_fq_codel ip_tables
  x_tables autofs4
  [  258.129215] Preemption disabled at:
  [  258.129216] [] vprintk_emit+0x11c/0x340
  [  258.129234] CPU: 0 PID: 1 Comm: systemd Tainted: G         C
  6.6.0-rc5-rockchip-rk356x #4
  [  258.129239] Hardware name: Rockchip RK3566 OPi 3B (DT)
  [  258.129243] Call trace:
  [  258.129245]  dump_backtrace+0xa0/0x128
  [  258.129252]  show_stack+0x20/0x38
  [  258.129256]  dump_stack_lvl+0x60/0xb0
  [  258.129265]  dump_stack+0x18/0x28
  [  258.129269]  __schedule_bug+0xa0/0xc8
  [  258.129274]  __schedule+0x9ac/0xd30
  [  258.129279]  schedule+0x60/0x100
  [  258.129282]  schedule_timeout+0x194/0x338
  [  258.129289]  rk3x_i2c_xfer_common.isra.0+0x384/0x498
  [  258.129296]  rk3x_i2c_xfer+0x20/0x60
  [  258.129300]  __i2c_transfer+0x194/0x648
  [  258.129308]  i2c_transfer+0x9c/0x130
  [  258.129313]  i2c_transfer_buffer_flags+0x64/0x98
  [  258.129318]  ssd1307fb_update_rect+0x42c/0x560 [ssd1307fb]
  [  258.129334]  ssd1307fb_defio_imageblit+0x34/0x50 [ssd1307fb]
  [  258.129343]  soft_cursor+0x13c/0x210
  [  258.129350]  bit_cursor+0x2dc/0x550
  [  258.129354]  fbcon_cursor+0xec/0x108
  [  258.129359]  hide_cursor+0x44/0xc8
  [  258.129365]  vt_console_print+0x398/0x3b0
  [  258.129370]  console_flush_all.isra.0+0x17c/0x410
  [  258.129377]  console_unlock+0x4c/0x100
  [  258.129382]  vprintk_emit+0x1c8/0x340
  [  258.129386]  vprintk_default+0x40/0x58
  [  258.129389]  vprintk+0xb8/0xd0
  [  258.129392]  _printk+0x68/0x98
  [  258.129398]  watchdog_release+0x170/0x230
  [  258.129404]  __fput+0xbc/0x288
  [  258.129409]  __fput_sync+0x58/0x70
  [  258.129413]  __arm64_sys_close+0x40/0x90
  [  258.129419]  invoke_syscall+0x4c/0x118
  [  258.129426]  el0_svc_common.constprop.0+0x48/0xf0
  [  258.129432]  do_el0_svc+0x24/0x38
  [  258.129437]  el0_svc+0x48/0x100
  [  258.129443]  el0t_64_sync_handler+0xc0/0xc8
  [  258.129448]  el0t_64_sync+0x190/0x198
  [  258.573087] ------------[ cut here ]------------
  [  258.573098] DEBUG_LOCKS_WARN_ON(val > preempt_count())
  [  258.573111] WARNING: CPU: 0 PID: 1 at kernel/sched/core.c:5871
  preempt_count_sub+0x9c/0x148
  [  258.573130] Modules linked in: algif_hash algif_skcipher af_alg bnep
  binfmt_misc lz4hc lz4 zram snd_soc_hdmi_codec brcmfmac_wcc hci_uart
  fb_ssd1306(C) fbtft(C) btqca btrtl btintel btsdio snd_soc_simple_card
  motorcomm pwm_fan snd_soc_simple_card_utils ssd130x_spi nls_iso8859_1
  ssd130x btbcm drm_shmem_helper display_connector brcmfmac ssd1307fb
  brcmutil bluetooth cfg80211 rfkill snd_soc_rockchip_i2s_tdm
  snd_soc_rk817 hantro_vpu snd_soc_core snd_compress snd_pcm_dmaengine
  v4l2_vp9 snd_pcm v4l2_h264 rockchip_rga snd_timer rk_crypto2
  spi_rockchip_sfc videobuf2_dma_contig snd sm3_generic v4l2_mem2mem
  videobuf2_dma_sg dwmac_rk sm3 soundcore videobuf2_memops videobuf2_v4l2
  stmmac_platform dw_hdmi_cec videodev videobuf2_common dw_hdmi_i2s_audio
  stmmac rk817_charger pcs_xpcs mc cpufreq_dt sch_fq_codel ip_tables
  x_tables autofs4
  [  258.573268] CPU: 0 PID: 1 Comm: systemd Tainted: G        WC
  6.6.0-rc5-rockchip-rk356x #4
  [  258.573274] Hardware name: Rockchip RK3566 OPi 3B (DT)
  ** 37 printk messages dropped **
  [  258.574064] Preemption disabled at:
  ** 42 printk messages dropped **
  [  259.190237] Preemption disabled at:

Track damage in the driver's private data under a spinlock and merge
multiple updates into a bounding rectangle.  Queue the existing
deferred-I/O work immediately for damage reported by fbdev drawing and
write helpers, so allocation and I2C transfers run from process context
without adding the configured mmap refresh delay.  Keep full-screen
updates for dirty mmap pages, for which no precise rectangle is available.

Tested on an RK3566 board with a 128x64 OLED by running five rounds of 250
KERN_EMERG messages in total while issuing framebuffer writes every 15 ms.
No atomic-sleep, preemption, or lockdep warning occurred.  Kprobe tracing
also confirmed that cursor-only damage remained an 8x16 partial update.

Fixes: a2ed00da5047 ("drivers/video: add support for the Solomon SSD1307 OLED Controller")
Cc: stable@vger.kernel.org
Signed-off-by: Hui Su 
Signed-off-by: Helge Deller 
Signed-off-by: Greg Kroah-Hartman

fbdev: pvr2fb: correct user pointer annotation and sentinel initializer

2026-09-07T15:36:53+00:00

commit 5dc2e70dd74b1f03e2e13bfb6922111d9e0adf90 upstream.

Add __user annotation to buf, as it is passed as a user pointer in
pin_user_pages_fast(). Use an empty initializer for the sentinel
board-table entry to avoid initializing a function pointer with an
integer literal.

Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202607131247.fpQ6eTc7-lkp@intel.com/
Cc: stable@vger.kernel.org
Signed-off-by: Florian Fuchs 
Signed-off-by: Helge Deller 
Signed-off-by: Greg Kroah-Hartman

fbdev: omapfb: panel-dsi-cm: initialize lock before registering display

2026-09-07T15:36:53+00:00

commit f8e43fe0f22b7137ce456e6fe3581d3098174f74 upstream.

dsicm_probe() registers the display before initializing ddata->lock.
Once omapdss_register_display() publishes the display, another consumer
can reach a dsicm callback that takes this mutex while it is still
uninitialized.

Initialize the mutex before registering the display so the published
callbacks always see a valid lock.

Fixes: f76ee892a99e ("omapfb: copy omapdss & displays for omapfb")
Cc: stable@vger.kernel.org
Signed-off-by: Runyu Xiao 
Signed-off-by: Helge Deller 
Signed-off-by: Greg Kroah-Hartman

fbdev: bitblit: bound-check glyph index in bit_cursor()

2026-08-08T06:08:58+00:00

bit_cursor() fetches the glyph under the cursor with

	c = scr_readw(vc_pos);
	src = vc_font.data + ((c & charmask) * w * height);

where charmask is 0x1ff when vc_hi_font_mask is set. The screen buffer
value comes directly from scr_readw() and may be larger than the current
font's glyph count.

Syzkaller triggers this via vcs_write(). The Call Trace shows
vcs_write() in vc_screen.c writing an arbitrary 16-bit value with
writev() to /dev/vcsa, which vcs_write_buf() in vc_screen.c stores via
vcs_scr_writew() without checking charcount. The stored value is later
read in bit_cursor() in bitblit.c.

When the font is changed from a font with 512 glyphs to a font with
256 glyphs, the screen buffer can retain characters with the high
bit set from the previous mode, which could also produce the same
out-of-bounds access.

  BUG: KASAN: global-out-of-bounds in soft_cursor+0x378/0x6bc drivers/video/fbdev/core/softcursor.c:70
  Read of size 16 at addr ffff800086c57970

  Call Trace:
   soft_cursor+0x378/0x6bc drivers/video/fbdev/core/softcursor.c:70
   bit_cursor+0xa90/0x1108 drivers/video/fbdev/core/bitblit.c:365
   fbcon_cursor+0x344/0x498 drivers/video/fbdev/core/fbcon.c:1427
   hide_cursor+0xdc/0x2d0 drivers/tty/vt/vt.c:883
   update_region+0x100/0x18c drivers/tty/vt/vt.c:669
   vcs_write+0x8ec/0xaf0 drivers/tty/vt/vc_screen.c:685

bit_putcs_aligned() and bit_putcs_unaligned() already clamp the glyph
index to vc_font.charcount. Apply the same clamp in bit_cursor() after
extracting the attribute and masking, before indexing fontdata.

The fix completes the bounds checking started in commit 18c4ef4e765a
("fbdev: bitblit: bound-check glyph index in bit_putcs*"), which missed
the cursor path.

This change should be safe because the clamp reuses the existing
contract from fbcon: charcount is maintained under console_lock in
con_font_set() and fbcon_font_set(), and hi_font_mask is cleared when
switching from 512 to 256 glyphs. When stale screen data with high bits
remains after a font switch, or when vcs_write() stores an arbitrary
value, clamping the index to 0 prevents the out-of-bounds read without
changing cursor semantics — the same fallback bit_putcs uses.

Reported-by: syzbot+61b1db46218109869c14@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=61b1db46218109869c14
Link: https://lore.kernel.org/all/6a75205c.01d0871a.3a0d52.0032.GAE@google.com/
Fixes: 18c4ef4e765a ("fbdev: bitblit: bound-check glyph index in bit_putcs*")
Cc: stable@vger.kernel.org
Assisted-by: Hermes:muse-spark-1.2 syzkaller
Signed-off-by: Rik van Riel 
Signed-off-by: Helge Deller

fbdev: Fix out-of-bounds access when rotating console after font resize

2026-08-08T06:08:58+00:00

[BUG]
Recently, we encountered a KASAN warning as follows:

BUG: KASAN: slab-out-of-bounds in ccw_putcs+0x8bd/0xa80
Read of size 1 at addr ff11000110067100 by task bash/1209
CPU: 10 UID: 0 PID: 1209 Comm: bash Not tainted 7.2.0-rc3 #69 PREEMPT(full)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014
 Call Trace:
  
  ...
  kasan_report+0xf0/0x120
  ? ccw_putcs+0x8bd/0xa80
  ccw_putcs+0x8bd/0xa80
  ? __pfx_ccw_putcs+0x10/0x10
  fbcon_putcs+0x338/0x410
  ? __pfx_ccw_putcs+0x10/0x10
  do_update_region+0x21d/0x450
  invert_screen+0x29d/0x5e0
  ? __kmalloc_noprof+0x493/0x640
  ? vc_do_resize+0x17c/0xe50
  clear_selection+0x4c/0x60
  vc_do_resize+0xaee/0xe50
  fbcon_modechanged+0x2bd/0x640
  rotate_all_store+0x298/0x380
  ...

reproduce:
1) issue two ioctls: first a KDFONTOP ioctl with op.op = KD_FONT_OP_SET,
op.width = 1 and op.height = 1, then a TIOCL_SETSEL ioctl
2) echo 2 > /sys/devices/virtual/graphics/fbcon/rotate_all
3) issue two ioctls: first a KDFONTOP ioctl with op.op = KD_FONT_OP_SET,
op.width = 8 and op.height = 1, then a TIOCL_SETSEL ioctl
4) echo 3 > /sys/devices/virtual/graphics/fbcon/rotate_all

[CAUSE]
The root cause is that fbcon_modechanged() first sets the current rotate's
corresponding ops. Subsequently, during vc_resize(), it may trigger
clear_selection(), and in fbcon_putcs->ccw_putcs[rotate=3], this can result
in an out-of-bounds access to "src". This happens because par->rotated.buf
is reallocated in fbcon_rotate_font():
1) When rotate=2, its size is (width + 7) / 8 * height
2) When rotate=3, its size is (height + 7) / 8 * width

And the call to fbcon_rotate_font() occurs after clear_selection(). In
other words, the fontbuffer is allocated using the size calculated from the
previous rotation 2, but before reallocating it with the new size,
con_putcs is already using the new rotation 3:

rotate_all_store
 fbcon_rotate_all
  fbcon_set_all_vcs
   fbcon_modechanged
    set_blitting_type
    ...
     par->bitops = &ccw_fbcon_bitops
    vc_resize
    ...
     clear_selection
      highlight
      ...
       do_update_region
	fbcon_putcs
	...
	 image.dy = vyres - ((xx + count) * vc->vc_font.width) [1]  // overflow!
	 ccw_putcs_aligned
	  // old buf size is still being used during the read!
	  src = par->rotated.buf + (scr_readw(s--) & charmask) * cellsize
	  fb_pad_aligned_buffer----[src KASAN!!!]	[2]
	  info->fbops->fb_imageblit(info, image)
	   sys_imageblit
	    fb_imageblit
	     fb_address_forward
	      // offset: image->dy * bits_per_line + image->dx * bpp
	      unsigned int bits = (unsigned int)adr->bits + offset
	      adr->address += (bits & ~(BITS_PER_LONG - 1u)) / BITS_PER_BYTE	[3]
	     fb_bitmap_imageblit
	     ...
	      fb_read_offset	// page fault!	[4]
    update_screen
     redraw_screen
     ...
      ccw_cursor
       soft_cursor
        memcpy(src, image->data, dsize)----[src KASAN again!!!]	[5]
     fbcon_switch
      fbcon_rotate_font
       font_data_rotate
	dst = kmalloc_array(charcount, d_cellsize, GFP_KERNEL)
       // the new size is allocated only here!
       par->rotated.buf = buf	[6]

[FIX]
A fairly obvious approach is to follow fbcon_switch(): in
fbcon_modechanged(), call rotate_font() before vc_resize() so that a
correctly sized buffer is allocated in time, as done in [6]. This fix is
necessary, but it is not sufficient on its own.

In [1] it causes an image.dy overflow (ccw_putcs: vyres = 768,
image.dy = 4294967040), because vc_cols has not been updated in time at
this point (it is likewise only updated after clear_selection()). This
allows (xx + count) * width to exceed vyres, causing image.dy to overflow.
Subsequently, address in [3] is incremented by an even larger amount, which
triggers a page fault at [4].

Therefore, a second fix is required in combination with the first: move
clear_selection() earlier, before set_blitting_type() in
fbcon_set_all_vcs(), to prevent the out-of-bounds access. fbcon_rotate()
has a similar problem, so add the same clear there. Since vc_is_sel() is
not exported, the fbdev side is currently forced to call clear_selection()
unconditionally, causing the global selection to be cleared prematurely.
And this will not cause any other significant impact.

Signed-off-by: Zizhi Wo 
Signed-off-by: Helge Deller

fbdev: core: Fix pointer desynchronization in fb_io_read()

2026-08-08T06:08:58+00:00

In fb_io_read(), if copy_to_user() performs a partial copy (e.g., due to
a faulty user buffer), the loop adjusts the chunk size 'c' and updates
the remaining 'count'. However, the hardware 'src' pointer has already
been eagerly advanced by the original chunk size.

If the loop is allowed to continue, the read will resume from an
incorrect, over-advanced offset. Since the remaining 'count' was only
decremented by the successful bytes, this desynchronization causes the
next iterations to execute more hardware reads than originally bounded,
eventually leading to out-of-bounds I/O reads.

Fix this by breaking out of the loop immediately upon a partial
copy_to_user(). A partial copy indicates a faulty user buffer, making
subsequent read attempts futile. Breaking out ensures we return the
number of successfully read bytes without risking out-of-bounds hardware
accesses in subsequent mismatched iterations.

Fixes: 6121cd9ef911 ("fbdev: Move I/O read and write code into helper functions")
Cc: stable@vger.kernel.org
Signed-off-by: Mingyu Wang <25181214217@stu.xidian.edu.cn>
Signed-off-by: Helge Deller

fbdev: serialize mode sysfs access with lock_fb_info()

2026-08-08T06:08:58+00:00

show_mode(), show_modes(), and store_mode() access fb_info->modelist
and fb_info->mode without holding lock_fb_info(). store_modes() takes
lock_fb_info() while replacing the modelist and freeing the old one.

A concurrent reader or writer can load a pointer to an old modelist
entry before store_modes() frees it, then dereference freed memory or
store a stale freed pointer in fb_info->mode.

Take lock_fb_info() in show_mode(), show_modes(), and store_mode() to
serialize with store_modes(). In show_mode(), copy the mode to the
stack and format after dropping the lock. In store_mode(), split
activate() into a _locked variant to avoid double-locking, and hold
the locks for the modelist walk, mode conversion, activation, and
fb_info->mode assignment together.

Cc: stable@vger.kernel.org # v7.1+
Signed-off-by: Melbin K Mathew 
Signed-off-by: Helge Deller

fbdev: clear fb_info->mode before deleting a videomode

2026-08-08T06:08:58+00:00

fb_set_var() can delete a mode from info->modelist when userspace
passes FB_ACTIVATE_INV_MODE through FBIOPUT_VSCREENINFO. The code
checks that the mode being deleted is not the current info->var and
that fbcon is not using it, but it does not check fb_info->mode.

fb_info->mode may still point into the modelist entry being deleted.
If the entry is freed, later mode sysfs reads through show_mode() can
dereference a stale pointer.

Clear fb_info->mode before calling fb_delete_videomode() when it
matches the mode being removed.

Cc: stable@vger.kernel.org # v7.1+
Signed-off-by: Melbin K Mathew 
Signed-off-by: Helge Deller

fbdev: bound mode sysfs output to the sysfs buffer

2026-08-08T06:08:58+00:00

mode_string() uses snprintf() which can return a value larger than the
remaining buffer space. show_modes() accumulates the return value into i
without checking whether i has reached PAGE_SIZE, causing the offset to
advance past the sysfs buffer if the modelist is long enough.

Add a size parameter to mode_string() and use scnprintf() to return
only the bytes actually written. Add an early return when offset
already exceeds the buffer. In show_modes(), stop accumulating once
the buffer is full.

Cc: stable@vger.kernel.org # v7.1+
Signed-off-by: Melbin K Mathew 
Signed-off-by: Helge Deller