CVE-2022-50332
Vulnérabilité non évaluée dans Linux (Linux)
Description
In the Linux kernel, the following vulnerability has been resolved: video/aperture: Call sysfb_disable() before removing PCI devices Call sysfb_disable() from aperture_remove_conflicting_pci_devices() before removing PCI devices. Without, simpledrm can still bind to simple-framebuffer devices after the hardware driver has taken over the hardware. Both drivers interfere with each other and results are undefined. Reported modesetting errors [1] are shown below. ---- snap ---- rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 13-.... } 7 jiffies s: 165 root: 0x2000/. rcu: blocking rcu_node structures (internal RCU debug): Task dump for CPU 13: task:X state:R running task stack: 0 pid: 4242 ppid: 4228 flags:0x00000008 Call Trace: <TASK> ? commit_tail+0xd7/0x130 ? drm_atomic_helper_commit+0x126/0x150 ? drm_atomic_commit+0xa4/0xe0 ? drm_plane_get_damage_clips.cold+0x1c/0x1c ? drm_atomic_helper_dirtyfb+0x19e/0x280 ? drm_mode_dirtyfb_ioctl+0x10f/0x1e0 ? drm_mode_getfb2_ioctl+0x2d0/0x2d0 ? drm_ioctl_kernel+0xc4/0x150 ? drm_ioctl+0x246/0x3f0 ? drm_mode_getfb2_ioctl+0x2d0/0x2d0 ? __x64_sys_ioctl+0x91/0xd0 ? do_syscall_64+0x60/0xd0 ? entry_SYSCALL_64_after_hwframe+0x4b/0xb5 </TASK> ... rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 13-.... } 30 jiffies s: 169 root: 0x2000/. rcu: blocking rcu_node structures (internal RCU debug): Task dump for CPU 13: task:X state:R running task stack: 0 pid: 4242 ppid: 4228 flags:0x0000400e Call Trace: <TASK> ? memcpy_toio+0x76/0xc0 ? memcpy_toio+0x1b/0xc0 ? drm_fb_memcpy_toio+0x76/0xb0 ? drm_fb_blit_toio+0x75/0x2b0 ? simpledrm_simple_display_pipe_update+0x132/0x150 ? drm_atomic_helper_commit_planes+0xb6/0x230 ? drm_atomic_helper_commit_tail+0x44/0x80 ? commit_tail+0xd7/0x130 ? drm_atomic_helper_commit+0x126/0x150 ? drm_atomic_commit+0xa4/0xe0 ? drm_plane_get_damage_clips.cold+0x1c/0x1c ? drm_atomic_helper_dirtyfb+0x19e/0x280 ? drm_mode_dirtyfb_ioctl+0x10f/0x1e0 ? drm_mode_getfb2_ioctl+0x2d0/0x2d0 ? drm_ioctl_kernel+0xc4/0x150 ? drm_ioctl+0x246/0x3f0 ? drm_mode_getfb2_ioctl+0x2d0/0x2d0 ? __x64_sys_ioctl+0x91/0xd0 ? do_syscall_64+0x60/0xd0 ? entry_SYSCALL_64_after_hwframe+0x4b/0xb5 </TASK> The problem was added by commit 5e0137612430 ("video/aperture: Disable and unregister sysfb devices via aperture helpers") to v6.0.3 and does not exist in the mainline branch. The mainline commit 5e0137612430 ("video/aperture: Disable and unregister sysfb devices via aperture helpers") has been backported from v6.0-rc1 to stable v6.0.3 from a larger patch series [2] that reworks fbdev framebuffer ownership. The backport misses a change to aperture_remove_conflicting_pci_devices(). Mainline itself is fine, because the function does not exist there as a result of the patch series. Instead of backporting the whole series, fix the additional function.
Gravité et risque d'exploitation
CVE-2022-50332 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 0.14 %, ce qui la place devant 2.9 % des CVE référencées.
Que faire ?
- Vérifiez si Linux (versions 6.0.3, <25a6688f27ff54f97adf7cce1d7e18c38bf51eb4, cfecfc98a78d97a49807531b5b224459bda877de, <6.0.6) 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.