CVE-2026-23266

fbdev: rivafb: fix divide error in nv3_arb()

Severity Score

"-"

*CVSS v-

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

In the Linux kernel, the following vulnerability has been resolved: fbdev: rivafb: fix divide error in nv3_arb() A userspace program can trigger the RIVA NV3 arbitration code by calling
the FBIOPUT_VSCREENINFO ioctl on /dev/fb*. When doing so, the driver
recomputes FIFO arbitration parameters in nv3_arb(), using state->mclk_khz
(derived from the PRAMDAC MCLK PLL) as a divisor without validating it
first. In a normal setup, state->mclk_khz is provided by the real hardware and is
non-zero. However, an attacker can construct a malicious or misconfigured
device (e.g. a crafted/emulated PCI device) that exposes a bogus PLL
configuration, causing state->mclk_khz to become zero. Once
nv3_get_param() calls nv3_arb(), the division by state->mclk_khz in the gns
calculation causes a divide error and crashes the kernel. Fix this by checking whether state->mclk_khz is zero and bailing out before
doing the division. The following log reveals it: rivafb: setting virtual Y resolution to 2184
divide error: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 0 PID: 2187 Comm: syz-executor.0 Not tainted 5.18.0-rc1+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
RIP: 0010:nv3_arb drivers/video/fbdev/riva/riva_hw.c:439 [inline]
RIP: 0010:nv3_get_param+0x3ab/0x13b0 drivers/video/fbdev/riva/riva_hw.c:546
Call Trace: nv3CalcArbitration.constprop.0+0x255/0x460 drivers/video/fbdev/riva/riva_hw.c:603 nv3UpdateArbitrationSettings drivers/video/fbdev/riva/riva_hw.c:637 [inline] CalcStateExt+0x447/0x1b90 drivers/video/fbdev/riva/riva_hw.c:1246 riva_load_video_mode+0x8a9/0xea0 drivers/video/fbdev/riva/fbdev.c:779 rivafb_set_par+0xc0/0x5f0 drivers/video/fbdev/riva/fbdev.c:1196 fb_set_var+0x604/0xeb0 drivers/video/fbdev/core/fbmem.c:1033 do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1109 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1188 __x64_sys_ioctl+0x122/0x190 fs/ioctl.c:856

En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta: fbdev: rivafb: corrige error de división en nv3_arb() Un programa de espacio de usuario puede activar el código de arbitraje RIVA NV3 llamando al ioctl FBIOPUT_VSCREENINFO en /dev/fb*. Al hacerlo, el controlador recalcula los parámetros de arbitraje FIFO en nv3_arb(), usando state->mclk_khz (derivado del PRAMDAC MCLK PLL) como divisor sin validarlo primero. En una configuración normal, state->mclk_khz es proporcionado por el hardware real y no es cero. Sin embargo, un atacante puede construir un dispositivo malicioso o mal configurado (p. ej., un dispositivo PCI manipulado/emulado) que expone una configuración PLL falsa, haciendo que state->mclk_khz se vuelva cero. Una vez que nv3_get_param() llama a nv3_arb(), la división por state->mclk_khz en el cálculo de gns causa un error de división y bloquea el kernel. Solucione esto verificando si state->mclk_khz es cero y saliendo antes de realizar la división. El siguiente registro lo revela: rivafb: estableciendo la resolución Y virtual a 2184
error de división: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 0 PID: 2187 Comm: syz-executor.0 No contaminado 5.18.0-rc1+ #1
Nombre del hardware: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
RIP: 0010:nv3_arb drivers/video/fbdev/riva/riva_hw.c:439 [inline]
RIP: 0010:nv3_get_param+0x3ab/0x13b0 drivers/video/fbdev/riva/riva_hw.c:546
Traza de llamada: nv3CalcArbitration.constprop.0+0x255/0x460 drivers/video/fbdev/riva/riva_hw.c:603 nv3UpdateArbitrationSettings drivers/video/fbdev/riva/riva_hw.c:637 [inline] CalcStateExt+0x447/0x1b90 drivers/video/fbdev/riva/riva_hw.c:1246 riva_load_video_mode+0x8a9/0xea0 drivers/video/fbdev/riva/fbdev.c:779 rivafb_set_par+0xc0/0x5f0 drivers/video/fbdev/riva/fbdev.c:1196 fb_set_var+0x604/0xeb0 drivers/video/fbdev/core/fbmem.c:1033 do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1109 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1188 __x64_sys_ioctl+0x122/0x190 fs/ioctl.c:856

*Credits: N/A

CVSS Scores

Attack Vector

Attack Complexity

Privileges Required

User Interaction

Scope

Confidentiality

Integrity

Availability

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2026-01-13 CVE Reserved
2026-03-18 CVE Published
2026-04-19 EPSS Updated
2026-05-11 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CAPEC

References (9)

URL	Tag	Source
https://git.kernel.org/stable/c/1da177e4c3f41524e886b7f1b8a0c1fc7321cac2	Vuln. Introduced

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/ec5a58f4fd581875593ea92a65485e1906a53c0f	2026-02-19
https://git.kernel.org/stable/c/52916878db2b8e3769743a94484729f0844352df	2026-02-19
https://git.kernel.org/stable/c/526460a96c5443e2fc0fd231edd1f9c49d2de26b	2026-02-19
https://git.kernel.org/stable/c/78daf5984d96edec3b920c72a93bd6821b8710b7	2026-02-19
https://git.kernel.org/stable/c/9efa0dc46270a8723c158c64afbcf1dead72b28c	2026-02-19
https://git.kernel.org/stable/c/3e4cbd1d46c246dfa684c8e9d8c20ae0b960c50a	2026-02-19
https://git.kernel.org/stable/c/73f0391e92d404da68f7484e57c106c5e673dc7e	2026-02-19
https://git.kernel.org/stable/c/0209e21e3c372fa2da04c39214bec0b64e4eb5f4	2026-02-14

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.12 < 5.10.251 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.12 < 5.10.251"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.12 < 5.15.201 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.12 < 5.15.201"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.12 < 6.1.164 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.12 < 6.1.164"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.12 < 6.6.127 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.12 < 6.6.127"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.12 < 6.12.74 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.12 < 6.12.74"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.12 < 6.18.13 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.12 < 6.18.13"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.12 < 6.19.3 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.12 < 6.19.3"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.12 < 7.0 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.12 < 7.0"		en		Affected