fbcon: always restore the old font data in fbcon_do_set_font… (CVE-2024-26798)

Summary

fbcon: always restore the old font data in fbcon_do_set_font()

Original description

The description as published by the source.

In the Linux kernel, the following vulnerability has been resolved:

fbcon: always restore the old font data in fbcon_do_set_font()

Commit a5a923038d70 (fbdev: fbcon: Properly revert changes when
vc_resize() failed) started restoring old font data upon failure (of
vc_resize()). But it performs so only for user fonts. It means that the
"system"/internal fonts are not restored at all. So in result, the very
first call to fbcon_do_set_font() performs no restore at all upon
failing vc_resize().

This can be reproduced by Syzkaller to crash the system on the next
invocation of font_get(). It's rather hard to hit the allocation failure
in vc_resize() on the first font_set(), but not impossible. Esp. if
fault injection is used to aid the execution/failure. It was
demonstrated by Sirius:
BUG: unable to handle page fault for address: fffffffffffffff8
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD cb7b067 P4D cb7b067 PUD cb7d067 PMD 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 8007 Comm: poc Not tainted 6.7.0-g9d1694dc91ce #20
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
RIP: 0010:fbcon_get_font+0x229/0x800 drivers/video/fbdev/core/fbcon.c:2286
Call Trace:

con_font_get drivers/tty/vt/vt.c:4558 [inline]
con_font_op+0x1fc/0xf20 drivers/tty/vt/vt.c:4673
vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline]
vt_ioctl+0x632/0x2ec0 drivers/tty/vt/vt_ioctl.c:752
tty_ioctl+0x6f8/0x…

Source: OSV.dev (Open Source Vulnerabilities) NVD OSV

Affected packages

Linux Kernel

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.15.151"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.81"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.0.0"},{"fixed":"6.6.21"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.7.9"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

Debian DEBIAN-CVE-2024-26798 linux Fixed in: 6.1.82-1
Ubuntu UBUNTU-CVE-2024-26798 linux-hwe-edge

Summary

Original description

Affected packages

Fix status by distribution

References