CVE-2022-49626: sfc: fix use after free when disabling sriov
First published: Wed Feb 26 2025(Updated: )
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
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | ||
| Linux Kernel | >=4.2<4.9.324 | |
| Linux Kernel | >=4.10<4.14.289 | |
| Linux Kernel | >=4.15<4.19.253 | |
| Linux Kernel | >=4.20<5.4.207 | |
| Linux Kernel | >=5.5<5.10.132 | |
| Linux Kernel | >=5.11<5.15.56 | |
| Linux Kernel | >=5.16<5.18.13 | |
| Linux Kernel | =5.19-rc1 | |
| Linux Kernel | =5.19-rc2 | |
| Linux Kernel | =5.19-rc3 | |
| Linux Kernel | =5.19-rc4 | |
| Linux Kernel | =5.19-rc5 | |
| Linux Kernel | =5.19-rc6 |
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Reference Links
- 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
Frequently Asked Questions
What is the severity of CVE-2022-49626?
CVE-2022-49626 has a high severity due to the potential for use after free vulnerabilities in the Linux kernel.
How do I fix CVE-2022-49626?
To fix CVE-2022-49626, upgrade to a patched version of the Linux kernel that resolves the use after free issue.
Which versions of the Linux kernel are affected by CVE-2022-49626?
CVE-2022-49626 affects multiple versions of the Linux kernel from 4.2 up to 5.19 release candidates.
What is the main issue described in CVE-2022-49626?
The main issue in CVE-2022-49626 is a use after free vulnerability when disabling SR-IOV in the Linux kernel.
Is CVE-2022-49626 specific to certain Linux distributions?
CVE-2022-49626 impacts all Linux distributions that use the affected versions of the kernel.
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