CVE-2025-38214

In the Linux kernel, the following vulnerability has been resolved: fbdev: Fix fb_set_var to prevent null-ptr-deref in fb_videomode_to_var 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.
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:*

Configuration 2 (hide)

cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

History

18 Dec 2025, 21:10

Type Values Removed Values Added
CPE cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:*
References () https://git.kernel.org/stable/c/05f6e183879d9785a3cdf2f08a498bc31b7a20aa - () https://git.kernel.org/stable/c/05f6e183879d9785a3cdf2f08a498bc31b7a20aa - Patch
References () https://git.kernel.org/stable/c/1a10d91766eb6ddfd5414e4785611e33a4fe0f9b - () https://git.kernel.org/stable/c/1a10d91766eb6ddfd5414e4785611e33a4fe0f9b - Patch
References () https://git.kernel.org/stable/c/3ca78032a388a0795201792b36e6fc9b6e6e8eed - () https://git.kernel.org/stable/c/3ca78032a388a0795201792b36e6fc9b6e6e8eed - Patch
References () https://git.kernel.org/stable/c/8a3a2887794b2c8e78b3e5d6e3de724527c9f41b - () https://git.kernel.org/stable/c/8a3a2887794b2c8e78b3e5d6e3de724527c9f41b - Patch
References () https://git.kernel.org/stable/c/b3071bb463ea1e6c686d0dc9638fc940f2f5cf17 - () https://git.kernel.org/stable/c/b3071bb463ea1e6c686d0dc9638fc940f2f5cf17 - Patch
References () https://git.kernel.org/stable/c/ee20216f12d9482cd70e44dae5e7fabb38367c71 - () https://git.kernel.org/stable/c/ee20216f12d9482cd70e44dae5e7fabb38367c71 - Patch
References () https://git.kernel.org/stable/c/fab201d72fde38d081e2c5d4ad25595c535b7b22 - () https://git.kernel.org/stable/c/fab201d72fde38d081e2c5d4ad25595c535b7b22 - Patch
References () https://git.kernel.org/stable/c/ff0e037241173b574b385bff53d67567b9816db5 - () https://git.kernel.org/stable/c/ff0e037241173b574b385bff53d67567b9816db5 - Patch
References () https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html - () https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html - Third Party Advisory, Mailing List
References () https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html - () https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html - Third Party Advisory, Mailing List
First Time Linux
Debian
Debian debian Linux
Linux linux Kernel
CVSS v2 : unknown
v3 : unknown
v2 : unknown
v3 : 5.5
CWE CWE-476

03 Nov 2025, 18:16

Type Values Removed Values Added
References
  • () https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html -
  • () https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html -

08 Jul 2025, 16:18

Type Values Removed Values Added
Summary
  • (es) En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: fbdev: Corregir fb_set_var para evitar la desreferencia null-ptr en fb_videomode_to_var Si fb_add_videomode() en fb_set_var() no puede asignar memoria para fb_videomode, más tarde puede conducir a una desreferencia null-ptr en fb_videomode_to_var(), ya que fb_info se registra sin tener el modo en modelist que se espera que esté allí, es decir, el que se describe en 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 ================================================================ El motivo es que fb_info->var se modifica en fb_set_var() y, a continuación, se llama a fb_videomode_to_var(). Si no se logra agregar el modo a fb_info->modelist, fb_set_var() devuelve un error, pero no restaura el valor anterior de fb_info->var. Si falla, restaure fb_info->var de la misma forma que se hizo anteriormente en la función. Encontrado por el Centro de Verificación de Linux (linuxtesting.org) con Syzkaller.

04 Jul 2025, 14:15

Type Values Removed Values Added
New CVE

Information

Published : 2025-07-04 14:15

Updated : 2025-12-18 21:10


NVD link : CVE-2025-38214

Mitre link : CVE-2025-38214

CVE.ORG link : CVE-2025-38214


JSON object : View

Products Affected

debian

  • debian_linux

linux

  • linux_kernel
CWE
CWE-476

NULL Pointer Dereference