# CVE-2021-47599: linux: In the Linux kernel, the following vulnerability has been resolved:  btrfs: use latest_dev in btrfs_show_devname  The...

CVE-2021-47599 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47599, released June 19, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-47599
- Priority: Routine
- CVSS: 4.7 (medium)
- EPSS: 0.0015
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 19, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  btrfs: use latest_dev in btrfs_show_devname  The test case btrfs/238 reports the warning below:   WARNING: CPU: 3 PID: 481 at fs/btrfs/super.c:2509 btrfs_show_devname+0x104/0x1e8 [btrfs]  CPU: 2 PID: 1 Comm: systemd Tainted: G        W  O 5.14.0-rc1-custom #72  Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015  Call trace:    btrfs_show_devname+0x108/0x1b4 [btrfs]    show_mountinfo+0x234/0x2c4    m_show+0x28/0x34    seq_read_iter+0x12c/0x3c4    vfs_read+0x29c/0x2c8    ksys_read+0x80/0xec    __arm64_sys_read+0x28/0x34    invoke_syscall+0x50/0xf8    do_el0_svc+0x88/0x138    el0_svc+0x2c/0x8c    el0t_64_sync_handler+0x84/0xe4    el0t_64_sync+0x198/0x19c  Reason: While btrfs_prepare_sprout() moves the fs_devices::devices into fs_devices::seed_list, the btrfs_show_devname() searches for the devices and found none, leading to the warning as in above.  Fix: latest_dev is updated according to the changes to the device list. That means we could use the latest_dev->name to show the device name in /proc/self/mounts, the pointer will be always valid as it's assigned before the device is deleted from the list in remove or replace. The RCU protection is sufficient as the device structure is freed after synchronization.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.15.15-1 | [DEBIAN-CVE-2021-47599](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47599.md) | Jun 19, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.15.15-1 | [DEBIAN-CVE-2021-47599](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47599.md) | Jun 19, 2024 |
| Linux | linux Debian 14 | 5.15.15-1 | [DEBIAN-CVE-2021-47599](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47599.md) | Jun 19, 2024 |

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