linux-stable.git/drivers/video/fbdev/core, branch v6.12.95

fbdev: modedb: Fix misaligned fields in the 1920x1080-60 mode

2026-07-04T11:43:35+00:00

commit d894c48a57d78206e4df9c90d4acfaf39394806a upstream.

The 1920x1080@60 modedb entry has one too many initializers before
its sync field: a stray "0" occupies the sync slot, which shifts the
remaining values by one field. The entry therefore decodes as
sync = 0, vmode = FB_SYNC_HOR_HIGH_ACT | FB_SYNC_VERT_HIGH_ACT (0x3,
i.e. FB_VMODE_INTERLACED | FB_VMODE_DOUBLE), and flag =
FB_VMODE_NONINTERLACED, instead of the intended sync = positive H/V,
vmode = non-interlaced.

fb_find_mode() then returns a 1920x1080 mode flagged as interlaced +
doublescan with active-low syncs. Drivers that honour var->vmode and
var->sync when programming display timing enable doublescan and the
wrong sync polarity, corrupting the output.

Drop the stray initializer so sync and vmode hold their intended
values (positive H/V sync, non-interlaced), matching the adjacent
1920x1200 entry.

Fixes: c8902258b2b8 ("fbdev: modedb: Add 1920x1080 at 60 Hz video mode")
Cc: stable@vger.kernel.org
Signed-off-by: Steffen Persvold 
Signed-off-by: Helge Deller 
Signed-off-by: Greg Kroah-Hartman

fbdev: modedb: fix a possible UAF in fb_find_mode()

2026-07-04T11:43:35+00:00

commit 85b6256469cebdac395e7447147e06b2e151014f upstream.

If mode_option is NULL, it is assigned from mode_option_buf:

  if (!mode_option) {
    fb_get_options(NULL, &mode_option_buf);
    mode_option = mode_option_buf;
  }

Later, name is assigned from mode_option:

  const char *name = mode_option;

However, mode_option_buf is freed before name is no longer used:

  kfree(mode_option_buf);

while name is still accessed by:

  if ((name_matches(db[i], name, namelen) ||

Since name aliases mode_option_buf, this may result in a
use-after-free.

Fix this by extending the lifetime of mode_option_buf until the end of the
function by using scope-based resource management for cleanup.

Signed-off-by: Tuo Li 
Cc: stable@vger.kernel.org # v6.5+
Signed-off-by: Helge Deller 
Signed-off-by: Greg Kroah-Hartman

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

2026-07-04T11:43:35+00:00

commit 7f08fc10fa3d3366dc3af723970bd03d7d6d10e3 upstream.

info->var, a framebuffer's current mode, is expected to have a matching
entry in info->modelist. var_to_display() relies on this and treats a
failed fb_match_mode() as "This should not happen". fb_set_var() keeps it
true by adding the mode to the list on every change, and
do_register_framebuffer() does the same at registration.

store_modes() replaces the modelist from userspace. fb_new_modelist()
validates the new modes but does not check that info->var still has a
match. It relies on fbcon_new_modelist() to re-point consoles, but that
only handles consoles mapped to the framebuffer. With fbcon unbound there
are none, so info->var is left describing a mode that is no longer in the
list.

A later console takeover runs var_to_display(), where fb_match_mode()
returns NULL and leaves fb_display[i].mode NULL. fbcon_switch() passes it
to display_to_var(), and fb_videomode_to_var() dereferences the NULL mode.

Keep the current mode in the list in fb_new_modelist(), the same way
fb_set_var() does.

Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Ian Bridges 
Signed-off-by: Helge Deller 
Signed-off-by: Greg Kroah-Hartman

fbdev: fix use-after-free in store_modes()

2026-07-04T11:43:32+00:00

commit 2c1c805c65fb7dc7524e20376d6987721e73a0b1 upstream.

store_modes() replaces a framebuffer's modelist with modes from userspace.
On success it frees the old modelist with fb_destroy_modelist(). Two
fields still point into that freed list.

One pointer is fb_display[i].mode, the mode a console is using.
fbcon_new_modelist() moves these pointers to the new list. It only does so
for consoles still mapped to the framebuffer. An unmapped console is
skipped and keeps its stale pointer. Unbinding fbcon, for example, sets
con2fb_map[i] to -1 but leaves fb_display[i].mode set. An
FBIOPUT_VSCREENINFO ioctl with FB_ACTIVATE_INV_MODE later reaches
fbcon_mode_deleted(). That function reads the stale fb_display[i].mode
through fb_mode_is_equal(). The read is a use-after-free.

The other pointer is fb_info->mode, the current mode. It is set through
the mode sysfs attribute. store_modes() does not update fb_info->mode, so
it is left pointing into the freed list. show_mode(), the attribute's read
handler, dereferences the stale fb_info->mode through mode_string(). The
read is a use-after-free.

Clear both pointers before freeing the list. Commit a1f305893074 ("fbcon:
Set fb_display[i]->mode to NULL when the mode is released") added the
helper fbcon_delete_modelist(). It clears every fb_display[i].mode that
points into a given list. So far it is called only from the unregister
path. Call it from store_modes() too, and set fb_info->mode to NULL.

Reported-by: syzbot+81c7c6b52649fd07299d@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=81c7c6b52649fd07299d
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/ajjoDhAi2y4ArSlz@dev/
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Ian Bridges 
Signed-off-by: Helge Deller 
Signed-off-by: Greg Kroah-Hartman

fbcon: Avoid OOB font access if console rotation fails

2026-05-17T15:14:34+00:00

[ Upstream commit e4ef723d8975a2694cc90733a6b888a5e2841842 ]

Clear the font buffer if the reallocation during console rotation fails
in fbcon_rotate_font(). The putcs implementations for the rotated buffer
will return early in this case. See [1] for an example.

Currently, fbcon_rotate_font() keeps the old buffer, which is too small
for the rotated font. Printing to the rotated console with a high-enough
character code will overflow the font buffer.

v2:
- fix typos in commit message

Signed-off-by: Thomas Zimmermann 
Fixes: 6cc50e1c5b57 ("[PATCH] fbcon: Console Rotation - Add support to rotate font bitmap")
Cc: stable@vger.kernel.org # v2.6.15+
Link: https://elixir.bootlin.com/linux/v6.19/source/drivers/video/fbdev/core/fbcon_ccw.c#L144 # [1]
Signed-off-by: Helge Deller 
[ renamed `par` to `ops` to match the 6.12 local pointer name ]
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

fbdev: defio: Disconnect deferred I/O from the lifetime of struct fb_info

2026-05-14T13:29:28+00:00

[ Upstream commit 9ded47ad003f09a94b6a710b5c47f4aa5ceb7429 ]

Hold state of deferred I/O in struct fb_deferred_io_state. Allocate an
instance as part of initializing deferred I/O and remove it only after
the final mapping has been closed. If the fb_info and the contained
deferred I/O meanwhile goes away, clear struct fb_deferred_io_state.info
to invalidate the mapping. Any access will then result in a SIGBUS
signal.

Fixes a long-standing problem, where a device hot-unplug happens while
user space still has an active mapping of the graphics memory. The hot-
unplug frees the instance of struct fb_info. Accessing the memory will
operate on undefined state.

Signed-off-by: Thomas Zimmermann 
Fixes: 60b59beafba8 ("fbdev: mm: Deferred IO support")
Cc: Helge Deller 
Cc: linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: stable@vger.kernel.org # v2.6.22+
Signed-off-by: Helge Deller 
[ replaced `kzalloc_obj()` with `kzalloc(sizeof(*fbdefio_state), GFP_KERNEL)` ]
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

fbcon: Remove struct fbcon_display.inverse

2026-03-04T12:21:58+00:00

[ Upstream commit 30baedeeeab524172abc0b58cb101e8df86b5be8 ]

The field inverse in struct fbcon_display is unused. Remove it.

Signed-off-by: Thomas Zimmermann 
Cc:  # v6.0+
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin

fbcon: check return value of con2fb_acquire_newinfo()

2026-03-04T12:21:57+00:00

[ Upstream commit 011a0502801c8536f64141a2b61362c14f456544 ]

If fbcon_open() fails when called from con2fb_acquire_newinfo() then
info->fbcon_par pointer remains NULL which is later dereferenced.

Add check for return value of the function con2fb_acquire_newinfo() to
avoid it.

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

Fixes: d1baa4ffa677 ("fbcon: set_con2fb_map fixes")
Cc: stable@vger.kernel.org
Signed-off-by: Andrey Vatoropin 
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin

drm, fbcon, vga_switcheroo: Avoid race condition in fbcon setup

2025-12-06T21:25:03+00:00

[ Upstream commit eb76d0f5553575599561010f24c277cc5b31d003 ]

Protect vga_switcheroo_client_fb_set() with console lock. Avoids OOB
access in fbcon_remap_all(). Without holding the console lock the call
races with switching outputs.

VGA switcheroo calls fbcon_remap_all() when switching clients. The fbcon
function uses struct fb_info.node, which is set by register_framebuffer().
As the fb-helper code currently sets up VGA switcheroo before registering
the framebuffer, the value of node is -1 and therefore not a legal value.
For example, fbcon uses the value within set_con2fb_map() [1] as an index
into an array.

Moving vga_switcheroo_client_fb_set() after register_framebuffer() can
result in VGA switching that does not switch fbcon correctly.

Therefore move vga_switcheroo_client_fb_set() under fbcon_fb_registered(),
which already holds the console lock. Fbdev calls fbcon_fb_registered()
from within register_framebuffer(). Serializes the helper with VGA
switcheroo's call to fbcon_remap_all().

Although vga_switcheroo_client_fb_set() takes an instance of struct fb_info
as parameter, it really only needs the contained fbcon state. Moving the
call to fbcon initialization is therefore cleaner than before. Only amdgpu,
i915, nouveau and radeon support vga_switcheroo. For all other drivers,
this change does nothing.

Signed-off-by: Thomas Zimmermann 
Link: https://elixir.bootlin.com/linux/v6.17/source/drivers/video/fbdev/core/fbcon.c#L2942 # [1]
Fixes: 6a9ee8af344e ("vga_switcheroo: initial implementation (v15)")
Acked-by: Javier Martinez Canillas 
Acked-by: Alex Deucher 
Cc: dri-devel@lists.freedesktop.org
Cc: nouveau@lists.freedesktop.org
Cc: amd-gfx@lists.freedesktop.org
Cc: linux-fbdev@vger.kernel.org
Cc:  # v2.6.34+
Link: https://patch.msgid.link/20251105161549.98836-1-tzimmermann@suse.de
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds

2025-11-13T20:34:35+00:00

[ Upstream commit 3637d34b35b287ab830e66048841ace404382b67 ]

Add bounds checking to prevent writes past framebuffer boundaries when
rendering text near screen edges. Return early if the Y position is off-screen
and clip image height to screen boundary. Break from the rendering loop if the
X position is off-screen. When clipping image width to fit the screen, update
the character count to match the clipped width to prevent buffer size
mismatches.

Without the character count update, bit_putcs_aligned and bit_putcs_unaligned
receive mismatched parameters where the buffer is allocated for the clipped
width but cnt reflects the original larger count, causing out-of-bounds writes.

Reported-by: syzbot+48b0652a95834717f190@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=48b0652a95834717f190
Suggested-by: Helge Deller 
Tested-by: syzbot+48b0652a95834717f190@syzkaller.appspotmail.com
Signed-off-by: Albin Babu Varghese 
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin