kernel/linux.git/drivers/video/fbdev/core/fbcon.c, branch v5.15.219

fbcon: Use correct type for vc_resize() return value

2026-08-23T12:17:18+00:00

[ Upstream commit 84202754fb1727dc3ee87f47104e4162ecc8ba3a ] The return value of vc_resize() is int, but fbcon_set_disp() stores it in an unsigned long variable. While the !ret check happens to work correctly by coincidence (negative values become large positive values), the types should match. Use int instead. Eliminates the following W=3 warning: drivers/video/fbdev/core/fbcon.c: In function 'fbcon_set_disp': drivers/video/fbdev/core/fbcon.c:1494:14: warning: implicit conversion from 'int' to 'unsigned long' [-Wconversion] Fixes: af0db3c1f898 ("fbdev: Fix vmalloc out-of-bounds write in fast_imageblit") Cc: stable@vger.kernel.org # v6.17+ Signed-off-by: Jiacheng Yu Reviewed-by: Thomas Zimmermann Signed-off-by: Helge Deller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

fbcon: Rename struct fbcon_ops to struct fbcon_par

2026-08-23T12:17:18+00:00

[ Upstream commit a6adbbc4c32a016146e117b1e9e5242724a75e10 ] The type struct fbcon_ops contains fbcon state and callbacks. As the callbacks will be removed from struct fbcon_ops, rename the data type to struct fbcon_par. Also rename the variables from ops to par. The _par postfix ("private access registers") is used throughout the fbdev subsystem for per-driver state. The fbcon pointer within struct fb_info is also named fbcon_par. Hence, the new naming fits existing practice. v2: - rename struct fbcon_ops to struct fbcon_par - fix build for CONFIG_FB_TILEBITTING=n (kernel test robot) - fix indention Signed-off-by: Thomas Zimmermann Reviewed-by: Sam Ravnborg Link: https://lore.kernel.org/r/20250909124616.143365-3-tzimmermann@suse.de Stable-dep-of: 84202754fb17 ("fbcon: Use correct type for vc_resize() return value") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

fbcon: fix NULL pointer dereference for a console without vc_data

2026-07-24T13:51:27+00:00

commit 5fae9a928482d4845bca169a3a098789203a1ca4 upstream. fbcon_new_modelist() runs when a framebuffer's modelist changes. For each console mapped to it with fb_display[i].mode set, it reads vc_cons[i].d and passes the vc_num to fbcon_set_disp(). This assumes a console with a mode set has a vc_data, but it can be NULL. fbcon_set_disp() sets fb_display[i].mode before it checks vc_data, and fbcon_deinit() leaves the mode set after the vc_data is freed. fbcon_new_modelist() then dereferences the NULL vc_data. Keep fb_display[i].mode set only while the console has a vc_data. Check vc_data before setting the mode in fbcon_set_disp(), and clear the mode in fbcon_deinit(). The existing mode check in fbcon_new_modelist() then skips such consoles. Reported-by: syzbot+42525d636f430fd5d983@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=42525d636f430fd5d983 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: fbcon: fix out-of-bounds read in err_out of fbcon_do_set_font()

2026-07-24T13:51:17+00:00

[ Upstream commit 8fdc8c2057eea08d40ce2c8eed41ff9e451c65c2 ] When fbcon_do_set_font() fails (e.g., due to a memory allocation failure inside vc_resize() under heavy memory pressure), it jumps to the `err_out` label to roll back the console state. However, the current rollback logic forgets to restore the `hi_font` state, leading to a severe state machine corruption. Earlier in the function, `set_vc_hi_font()` might be called to change `vc->vc_hi_font_mask` and mutate the screen buffer. If `vc_resize()` subsequently fails, the `err_out` path restores `vc_font.charcount` but entirely skips rolling back the `vc_hi_font_mask` and the screen buffer. This mismatch leaves the terminal in a desynchronized state. Because `vc_hi_font_mask` remains set, the VT subsystem will still accept character indices greater than 255 from userspace and write them to the screen buffer. Subsequent rendering calls (e.g., `fbcon_putcs()`) will then use these inflated indices to access the reverted, 256-character font array, leading to a deterministic out-of-bounds read and potential kernel memory disclosure. Fix this by adding the missing rollback logic for the `hi_font` mask and screen buffer in the error path. Fixes: a5a923038d70 ("fbdev: fbcon: Properly revert changes when vc_resize() failed") Cc: stable@vger.kernel.org Signed-off-by: Mingyu Wang <25181214217@stu.xidian.edu.cn> Reviewed-by: Thomas Zimmermann Signed-off-by: Helge Deller [ Adjust context ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

fbcon: Set fb_display[i]->mode to NULL when the mode is released

2026-04-18T08:33:35+00:00

[ Upstream commit a1f3058930745d2b938b6b4f5bd9630dc74b26b7 ] Recently, we discovered the following issue through syzkaller: BUG: KASAN: slab-use-after-free in fb_mode_is_equal+0x285/0x2f0 Read of size 4 at addr ff11000001b3c69c by task syz.xxx ... Call Trace: dump_stack_lvl+0xab/0xe0 print_address_description.constprop.0+0x2c/0x390 print_report+0xb9/0x280 kasan_report+0xb8/0xf0 fb_mode_is_equal+0x285/0x2f0 fbcon_mode_deleted+0x129/0x180 fb_set_var+0xe7f/0x11d0 do_fb_ioctl+0x6a0/0x750 fb_ioctl+0xe0/0x140 __x64_sys_ioctl+0x193/0x210 do_syscall_64+0x5f/0x9c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Based on experimentation and analysis, during framebuffer unregistration, only the memory of fb_info->modelist is freed, without setting the corresponding fb_display[i]->mode to NULL for the freed modes. This leads to UAF issues during subsequent accesses. Here's an example of reproduction steps: 1. With /dev/fb0 already registered in the system, load a kernel module to register a new device /dev/fb1; 2. Set fb1's mode to the global fb_display[] array (via FBIOPUT_CON2FBMAP); 3. Switch console from fb to VGA (to allow normal rmmod of the ko); 4. Unload the kernel module, at this point fb1's modelist is freed, leaving a wild pointer in fb_display[]; 5. Trigger the bug via system calls through fb0 attempting to delete a mode from fb0. Add a check in do_unregister_framebuffer(): if the mode to be freed exists in fb_display[], set the corresponding mode pointer to NULL. [ The context change is due to the commit 2c0c19b681d5 ("fbdev: fbmem: Fix double free of 'fb_info->pixmap.addr'") in v5.16 which is irrelevant to the logic of this patch. ] Signed-off-by: Quanmin Yan Reviewed-by: Thomas Zimmermann Signed-off-by: Helge Deller Cc: stable@vger.kernel.org Signed-off-by: Johnny Hao Signed-off-by: Sasha Levin

fbcon: check return value of con2fb_acquire_newinfo()

2026-04-18T08:33:08+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

fbcon: move more common code into fb_open()

2026-04-18T08:33:08+00:00

[ Upstream commit d443d93864726ad68c0a741d1e7b03934a9af143 ] No idea why con2fb_acquire_newinfo() initializes much less than fbcon_startup(), but so be it. From a quick look most of the un-initialized stuff should be fairly harmless, but who knows. Note that the error handling for the con2fb_acquire_newinfo() failure case was very strange: Callers updated con2fb_map to the new value before calling this function, but upon error con2fb_acquire_newinfo reset it to the old value. Since I removed the call to fbcon_release anyway that strange error path was sticking out like a sore thumb, hence I removed it. Which also allows us to remove the oldidx parameter from that function. v2: Explain what's going on with oldidx and error paths (Sam) v3: Drop unused variable (0day) v4: Rebased over bisect fix in previous patch, unchagend end result. Acked-by: Sam Ravnborg (v2) Acked-by: Thomas Zimmermann Cc: kernel test robot Signed-off-by: Daniel Vetter Cc: Daniel Vetter Cc: Greg Kroah-Hartman Cc: Tetsuo Handa Cc: Thomas Zimmermann Cc: Claudio Suarez Cc: Du Cheng Link: https://patchwork.freedesktop.org/patch/msgid/20220405210335.3434130-12-daniel.vetter@ffwll.ch Stable-dep-of: 011a0502801c ("fbcon: check return value of con2fb_acquire_newinfo()") Signed-off-by: Sasha Levin

fbcon: Extract fbcon_open/release helpers

2026-04-18T08:33:07+00:00

[ Upstream commit bd6026a8c4e6b7edf4bafcb71da885b284b8f4fd ] There's two minor behaviour changes in here: - in error paths we now consistently call fb_ops->fb_release - fb_release really can't fail (fbmem.c ignores it too) and there's no reasonable cleanup we can do anyway. Note that everything in fbcon.c is protected by the big console_lock() lock (especially all the global variables), so the minor changes in ordering of setup/cleanup do not matter. v2: Explain a bit better why this is all correct (Sam) Acked-by: Sam Ravnborg Signed-off-by: Daniel Vetter Cc: Daniel Vetter Cc: Claudio Suarez Cc: Greg Kroah-Hartman Cc: Tetsuo Handa Cc: Du Cheng Link: https://patchwork.freedesktop.org/patch/msgid/20220405210335.3434130-10-daniel.vetter@ffwll.ch Stable-dep-of: 011a0502801c ("fbcon: check return value of con2fb_acquire_newinfo()") Signed-off-by: Sasha Levin

fbcon: Use delayed work for cursor

2026-04-18T08:33:07+00:00

[ Upstream commit 3b0fb6ab25dda03f6077bf8fce9407bb0d4db6ea ] Allows us to delete a bunch of hand-rolled stuff using a timer plus a separate work). Also to simplify the code we initialize the cursor_work completely when we allocate the fbcon_ops structure, instead of trying to cope with console re-initialization. The motiviation here is that fbcon code stops using the fb_info.queue, which helps with locking issues around cleanup and all that in a later patch. Also note that this allows us to ditch the hand-rolled work cleanup in fbcon_exit - we already call fbcon_del_cursor_timer, which takes care of everything. Plus this was racy anyway. v2: - Only INIT_DELAYED_WORK when kzalloc succeeded (Tetsuo) - Explain that we replace both the timer and a work with the combined delayed_work (Javier) Reviewed-by: Javier Martinez Canillas Acked-by: Thomas Zimmermann Signed-off-by: Daniel Vetter Cc: Daniel Vetter Cc: Claudio Suarez Cc: Du Cheng Cc: Thomas Zimmermann Cc: Greg Kroah-Hartman Cc: Tetsuo Handa Link: https://patchwork.freedesktop.org/patch/msgid/20220405210335.3434130-7-daniel.vetter@ffwll.ch Stable-dep-of: 011a0502801c ("fbcon: check return value of con2fb_acquire_newinfo()") Signed-off-by: Sasha Levin

fbcon: Fix OOB access in font allocation

2025-10-02T11:39:14+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