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Amazon Linux 2023: CVE-2024-26798: Medium priority package update for kernel (Multiple Advisories)

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Amazon Linux 2023: CVE-2024-26798: Medium priority package update for kernel (Multiple Advisories)

Severity
5
CVSS
(AV:L/AC:L/Au:S/C:N/I:N/A:C)
Published
04/04/2024
Created
02/14/2025
Added
02/14/2025
Modified
02/14/2025

Description

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.) A  vulnerability was found in the Linux kernel in the framebuffer console (`fbcon`). The`fbcon_do_set_font()` function failed to restore the old font data correctly. This flaw could lead to improper font rendering and display issues on the console.

Solution(s)

  • amazon-linux-2023-upgrade-bpftool
  • amazon-linux-2023-upgrade-bpftool-debuginfo
  • amazon-linux-2023-upgrade-kernel
  • amazon-linux-2023-upgrade-kernel-debuginfo
  • amazon-linux-2023-upgrade-kernel-debuginfo-common-aarch64
  • amazon-linux-2023-upgrade-kernel-debuginfo-common-x86-64
  • amazon-linux-2023-upgrade-kernel-devel
  • amazon-linux-2023-upgrade-kernel-headers
  • amazon-linux-2023-upgrade-kernel-libbpf
  • amazon-linux-2023-upgrade-kernel-libbpf-devel
  • amazon-linux-2023-upgrade-kernel-libbpf-static
  • amazon-linux-2023-upgrade-kernel-livepatch-6-1-82-99-168
  • amazon-linux-2023-upgrade-kernel-modules-extra
  • amazon-linux-2023-upgrade-kernel-modules-extra-common
  • amazon-linux-2023-upgrade-kernel-tools
  • amazon-linux-2023-upgrade-kernel-tools-debuginfo
  • amazon-linux-2023-upgrade-kernel-tools-devel
  • amazon-linux-2023-upgrade-perf
  • amazon-linux-2023-upgrade-perf-debuginfo
  • amazon-linux-2023-upgrade-python3-perf
  • amazon-linux-2023-upgrade-python3-perf-debuginfo

References

  • https://attackerkb.com/topics/cve-2024-26798
  • CVE - 2024-26798
  • https://alas.aws.amazon.com/AL2023/ALAS-2024-603.html
  • https://alas.aws.amazon.com/AL2023/ALAS-2024-784.html
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