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CVE-2024-26798

Vulnérabilité non évaluée dans Linux (Linux)

CVSS 0.0 · Non évaluée
EPSS 0.3%
Linux•Linux•Versions : <=6.1.*, 5.15.151, <5.15.151, <00d6a284fcf3fad1b7e1b5bc3cd87cbfb60ce03f, 0, <ae68f57df3335679653868fafccd8c88ef84ae98, ebd6f886aa2447fcfcdce5450c9e1028e1d681bb, 6.8, 5.15.64, 6.1.81, <=6.6.*, 6.0, <6.0, <2f91a96b892fab2f2543b4a55740c5bee36b1a6b, 5.19.6, <73a6bd68a1342f3a44cac9dffad81ad6a003e520, <5.20, a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24, 868749a7456dc48e93887a8474194e2ee6d6c21f, <=*, <20a4b5214f7bee13c897477168c77bbf79683c3d, <=5.15.*, <=6.7.*, 6.6.21, f08ccb792d3eaf1dc62d8cbf6a30d6522329f660, 6.7.9, <a2c881413dcc5d801bdc9535e51270cc88cb9cd8

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.)

Gravité et risque d'exploitation

CVE-2024-26798 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.33 %, ce qui la place devant 24.3 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, 5.15.151, <5.15.151, <00d6a284fcf3fad1b7e1b5bc3cd87cbfb60ce03f, 0, <ae68f57df3335679653868fafccd8c88ef84ae98, ebd6f886aa2447fcfcdce5450c9e1028e1d681bb, 6.8, 5.15.64, 6.1.81, <=6.6.*, 6.0, <6.0, <2f91a96b892fab2f2543b4a55740c5bee36b1a6b, 5.19.6, <73a6bd68a1342f3a44cac9dffad81ad6a003e520, <5.20, a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24, 868749a7456dc48e93887a8474194e2ee6d6c21f, <=*, <20a4b5214f7bee13c897477168c77bbf79683c3d, <=5.15.*, <=6.7.*, 6.6.21, f08ccb792d3eaf1dc62d8cbf6a30d6522329f660, 6.7.9, <a2c881413dcc5d801bdc9535e51270cc88cb9cd8) est présent sur votre parc.
  • Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
  • À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
  • Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

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