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:
<TASK>
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+0x6f8/0x1570 drivers/tty/tty_io.c:2803
vfs_ioctl fs/ioctl.c:51 [inline]
...
So restore the font data in any case, not only for user fonts. Note the
later 'if' is now protected by 'old_userfont' and not 'old_data' as the
latter is always set now. (And it is supposed to be non-NULL. Otherwise
we would see the bug above again.)
Metrics
Affected Vendors & Products
References
History
Tue, 01 Apr 2025 21:00:00 +0000
Type | Values Removed | Values Added |
---|---|---|
First Time appeared |
Linux
Linux linux Kernel |
|
Weaknesses | CWE-770 | |
CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.8:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.8:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.8:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.8:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.8:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.8:rc6:*:*:*:*:*:* |
|
Vendors & Products |
Linux
Linux linux Kernel |
Wed, 06 Nov 2024 08:15:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Metrics |
ssvc
|
Thu, 19 Sep 2024 10:45:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Weaknesses | CWE-366 |

Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2024-12-19T08:47:39.931Z
Reserved: 2024-02-19T14:20:24.179Z
Link: CVE-2024-26798

Updated: 2024-08-02T00:14:13.539Z

Status : Analyzed
Published: 2024-04-04T09:15:08.897
Modified: 2025-04-01T20:35:32.650
Link: CVE-2024-26798
