Bug 2376394 (CVE-2025-38198) - CVE-2025-38198 kernel: fbcon: Make sure modelist not set on unregistered console
Summary: CVE-2025-38198 kernel: fbcon: Make sure modelist not set on unregistered console
Keywords:
Status: NEW
Alias: CVE-2025-38198
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2025-07-04 14:03 UTC by OSIDB Bzimport
Modified: 2025-07-14 05:40 UTC (History)
0 users

Fixed In Version:
Clone Of:
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Description OSIDB Bzimport 2025-07-04 14:03:38 UTC
In the Linux kernel, the following vulnerability has been resolved:

fbcon: Make sure modelist not set on unregistered console

It looks like attempting to write to the "store_modes" sysfs node will
run afoul of unregistered consoles:

UBSAN: array-index-out-of-bounds in drivers/video/fbdev/core/fbcon.c:122:28
index -1 is out of range for type 'fb_info *[32]'
...
 fbcon_info_from_console+0x192/0x1a0 drivers/video/fbdev/core/fbcon.c:122
 fbcon_new_modelist+0xbf/0x2d0 drivers/video/fbdev/core/fbcon.c:3048
 fb_new_modelist+0x328/0x440 drivers/video/fbdev/core/fbmem.c:673
 store_modes+0x1c9/0x3e0 drivers/video/fbdev/core/fbsysfs.c:113
 dev_attr_store+0x55/0x80 drivers/base/core.c:2439

static struct fb_info *fbcon_registered_fb[FB_MAX];
...
static signed char con2fb_map[MAX_NR_CONSOLES];
...
static struct fb_info *fbcon_info_from_console(int console)
...
        return fbcon_registered_fb[con2fb_map[console]];

If con2fb_map contains a -1 things go wrong here. Instead, return NULL,
as callers of fbcon_info_from_console() are trying to compare against
existing "info" pointers, so error handling should kick in correctly.

Comment 1 Avinash Hanwate 2025-07-07 04:40:05 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025070417-CVE-2025-38198-b902@gregkh/T


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