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

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 fbcon 中的 fbcon_do_set_font 存在安全问题。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.33% · P24

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 868749a7456dc48e93887a8474194e2ee6d6c21f< ae68f57df3335679653868fafccd8c88ef84ae98 affected
ebd6f886aa2447fcfcdce5450c9e1028e1d681bb< 20a4b5214f7bee13c897477168c77bbf79683c3d affected
a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24< 2f91a96b892fab2f2543b4a55740c5bee36b1a6b affected
a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24< 73a6bd68a1342f3a44cac9dffad81ad6a003e520 affected
a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24< a2c881413dcc5d801bdc9535e51270cc88cb9cd8 affected
a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24< 00d6a284fcf3fad1b7e1b5bc3cd87cbfb60ce03f affected
f08ccb792d3eaf1dc62d8cbf6a30d6522329f660 affected
5.15.64< 5.15.151 affected
… +8 more rows
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I. Basic Information for CVE-2024-26798

Vulnerability Information
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Vulnerability Title
fbcon: always restore the old font data in fbcon_do_set_font()
Source: CVE Program / CVE List V5
Vulnerability 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.)
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 fbcon 中的 fbcon_do_set_font 存在安全问题。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 868749a7456dc48e93887a8474194e2ee6d6c21f ~ ae68f57df3335679653868fafccd8c88ef84ae98 -
Linux Linux 6.0 -

II. Public POCs for CVE-2024-26798

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III. Intelligence Information for CVE-2024-26798

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Other References for CVE-2024-26798 (4)

Same Patch Batch · Linux · 2024-04-04 · 32 CVEs total

CVE-2024-26782 9.8 CRITICAL mptcp: fix double-free on socket dismantle
CVE-2024-26800 9.8 CRITICAL tls: fix use-after-free on failed backlog decryption
CVE-2024-26801 8.8 HIGH Bluetooth: Avoid potential use-after-free in hci_error_reset
CVE-2024-26792 7.8 HIGH btrfs: fix double free of anonymous device after snapshot creation failure
CVE-2024-26809 7.8 HIGH netfilter: nft_set_pipapo: release elements in clone only from destroy path
CVE-2024-26808 7.8 HIGH netfilter: nft_chain_filter: handle NETDEV_UNREGISTER for inet/ingress basechain
CVE-2024-26807 7.8 HIGH spi: cadence-qspi: fix pointer reference in runtime PM hooks
CVE-2024-26804 7.8 HIGH net: ip_tunnel: prevent perpetual headroom growth
CVE-2024-26802 7.8 HIGH stmmac: Clear variable when destroying workqueue
CVE-2024-26797 7.8 HIGH drm/amd/display: Prevent potential buffer overflow in map_hw_resources
CVE-2024-26795 7.8 HIGH riscv: Sparse-Memory/vmemmap out-of-bounds fix
CVE-2024-26793 7.8 HIGH gtp: fix use-after-free and null-ptr-deref in gtp_newlink()
CVE-2024-26786 7.8 HIGH iommufd: Fix iopt_access_list_id overwrite bug
CVE-2024-26789 7.8 HIGH crypto: arm64/neonbs - fix out-of-bounds access on short input
CVE-2024-26799 7.0 HIGH ASoC: qcom: Fix uninitialized pointer dmactl
CVE-2024-26785 iommufd: Fix protection fault in iommufd_test_syz_conv_iova
CVE-2024-26746 dmaengine: idxd: Ensure safe user copy of completion record
CVE-2024-26750 af_unix: Drop oob_skb ref before purging queue in GC.
CVE-2024-26780 af_unix: Fix task hung while purging oob_skb in GC.
CVE-2024-26806 spi: cadence-qspi: remove system-wide suspend helper calls from runtime PM hooks

Showing top 20 of 32 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2024-26798

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