CVE-2022-49626

Description

In the Linux kernel, the following vulnerability has been resolved: sfc: fix use after free when disabling sriov Use after free is detected by kfence when disabling sriov. What was read after being freed was vf->pci_dev: it was freed from pci_disable_sriov and later read in efx_ef10_sriov_free_vf_vports, called from efx_ef10_sriov_free_vf_vswitching. Set the pointer to NULL at release time to not trying to read it later. Reproducer and dmesg log (note that kfence doesn't detect it every time): $ echo 1 > /sys/class/net/enp65s0f0np0/device/sriov_numvfs $ echo 0 > /sys/class/net/enp65s0f0np0/device/sriov_numvfs BUG: KFENCE: use-after-free read in efx_ef10_sriov_free_vf_vswitching+0x82/0x170 [sfc] Use-after-free read at 0x00000000ff3c1ba5 (in kfence-#224): efx_ef10_sriov_free_vf_vswitching+0x82/0x170 [sfc] efx_ef10_pci_sriov_disable+0x38/0x70 [sfc] efx_pci_sriov_configure+0x24/0x40 [sfc] sriov_numvfs_store+0xfe/0x140 kernfs_fop_write_iter+0x11c/0x1b0 new_sync_write+0x11f/0x1b0 vfs_write+0x1eb/0x280 ksys_write+0x5f/0xe0 do_syscall_64+0x5c/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae kfence-#224: 0x00000000edb8ef95-0x00000000671f5ce1, size=2792, cache=kmalloc-4k allocated by task 6771 on cpu 10 at 3137.860196s: pci_alloc_dev+0x21/0x60 pci_iov_add_virtfn+0x2a2/0x320 sriov_enable+0x212/0x3e0 efx_ef10_sriov_configure+0x67/0x80 [sfc] efx_pci_sriov_configure+0x24/0x40 [sfc] sriov_numvfs_store+0xba/0x140 kernfs_fop_write_iter+0x11c/0x1b0 new_sync_write+0x11f/0x1b0 vfs_write+0x1eb/0x280 ksys_write+0x5f/0xe0 do_syscall_64+0x5c/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae freed by task 6771 on cpu 12 at 3170.991309s: device_release+0x34/0x90 kobject_cleanup+0x3a/0x130 pci_iov_remove_virtfn+0xd9/0x120 sriov_disable+0x30/0xe0 efx_ef10_pci_sriov_disable+0x57/0x70 [sfc] efx_pci_sriov_configure+0x24/0x40 [sfc] sriov_numvfs_store+0xfe/0x140 kernfs_fop_write_iter+0x11c/0x1b0 new_sync_write+0x11f/0x1b0 vfs_write+0x1eb/0x280 ksys_write+0x5f/0xe0 do_syscall_64+0x5c/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae

Gravité et risque d'exploitation

CVE-2022-49626 obtient un score CVSS de 7.8/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.28 %, ce qui la place devant 18.8 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <4.2, 5.18.13, 3c5eb87605e85146a78de589b5070a37862425db, 0, <3199e34912d84cdfb8a93a984c5ae5c73fb13e84, 5.19, 5.15.56, 4.9.324, <=4.9.*, <=5.10.*, <bcad880865bfb421885364b1f0c7351280fe2b97, <=4.14.*, <c9e75bb22a26e391f189f5a5133dd63dcb57fdaa, <=5.18.*, <=5.4.*, 4.19.253, <9c854ae512b89229aeee93849e9bd4c115b37909, <=4.19.*, 5.10.132, <e435c4aeeaa073091f7f3b7735af2ef5c97d63f2, 4.2, <c2240500817b3b4b996cdf2a461a3a5679f49b94, <=*, <58d93e9d160c0de6d867c7eb4c2206671a351eb1, <=5.15.*, <ebe41da5d47ac0fff877e57bd14c54dccf168827, 5.4.207, 4.14.289) 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

• https://git.kernel.org/stable/c/3199e34912d84cdfb8a93a984c5ae5c73fb13e84
• https://git.kernel.org/stable/c/c9e75bb22a26e391f189f5a5133dd63dcb57fdaa
• https://git.kernel.org/stable/c/9c854ae512b89229aeee93849e9bd4c115b37909
• https://git.kernel.org/stable/c/bcad880865bfb421885364b1f0c7351280fe2b97
• https://git.kernel.org/stable/c/c2240500817b3b4b996cdf2a461a3a5679f49b94
• https://git.kernel.org/stable/c/58d93e9d160c0de6d867c7eb4c2206671a351eb1
• https://git.kernel.org/stable/c/e435c4aeeaa073091f7f3b7735af2ef5c97d63f2
• https://git.kernel.org/stable/c/ebe41da5d47ac0fff877e57bd14c54dccf168827