| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-50217: btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids() |
| |
| Mounting btrfs from two images (which have the same one fsid and two |
| different dev_uuids) in certain executing order may trigger an UAF for |
| variable 'device->bdev_file' in __btrfs_free_extra_devids(). And |
| following are the details: |
| |
| 1. Attach image_1 to loop0, attach image_2 to loop1, and scan btrfs |
| devices by ioctl(BTRFS_IOC_SCAN_DEV): |
| |
| / btrfs_device_1 → loop0 |
| fs_device |
| \ btrfs_device_2 → loop1 |
| 2. mount /dev/loop0 /mnt |
| btrfs_open_devices |
| btrfs_device_1->bdev_file = btrfs_get_bdev_and_sb(loop0) |
| btrfs_device_2->bdev_file = btrfs_get_bdev_and_sb(loop1) |
| btrfs_fill_super |
| open_ctree |
| fail: btrfs_close_devices // -ENOMEM |
| btrfs_close_bdev(btrfs_device_1) |
| fput(btrfs_device_1->bdev_file) |
| // btrfs_device_1->bdev_file is freed |
| btrfs_close_bdev(btrfs_device_2) |
| fput(btrfs_device_2->bdev_file) |
| |
| 3. mount /dev/loop1 /mnt |
| btrfs_open_devices |
| btrfs_get_bdev_and_sb(&bdev_file) |
| // EIO, btrfs_device_1->bdev_file is not assigned, |
| // which points to a freed memory area |
| btrfs_device_2->bdev_file = btrfs_get_bdev_and_sb(loop1) |
| btrfs_fill_super |
| open_ctree |
| btrfs_free_extra_devids |
| if (btrfs_device_1->bdev_file) |
| fput(btrfs_device_1->bdev_file) // UAF ! |
| |
| Fix it by setting 'device->bdev_file' as 'NULL' after closing the |
| btrfs_device in btrfs_close_one_device(). |
| |
| The Linux kernel CVE team has assigned CVE-2024-50217 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.8 with commit 142388194191a3edc9ba01cfcfd8b691e0971fb2 and fixed in 6.11.7 with commit 47a83f8df39545f3f552bb6a1b6d9c30e37621dd |
| Issue introduced in 4.8 with commit 142388194191a3edc9ba01cfcfd8b691e0971fb2 and fixed in 6.12 with commit aec8e6bf839101784f3ef037dcdb9432c3f32343 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2024-50217 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| fs/btrfs/volumes.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/47a83f8df39545f3f552bb6a1b6d9c30e37621dd |
| https://git.kernel.org/stable/c/aec8e6bf839101784f3ef037dcdb9432c3f32343 |
