# CVE-2021-47638: linux: In the Linux kernel, the following vulnerability has been resolved:  ubifs: rename_whiteout: Fix double free for whit...

CVE-2021-47638 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47638, released February 26, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-47638
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0026
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 26, 2025

## Description

In the Linux kernel, the following vulnerability has been resolved:  ubifs: rename_whiteout: Fix double free for whiteout_ui->data  'whiteout_ui->data' will be freed twice if space budget fail for rename whiteout operation as following process:  rename_whiteout   dev = kmalloc   whiteout_ui->data = dev   kfree(whiteout_ui->data)  // Free first time   iput(whiteout)     ubifs_free_inode       kfree(ui->data)	    // Double free!  KASAN reports: ================================================================== BUG: KASAN: double-free or invalid-free in ubifs_free_inode+0x4f/0x70 Call Trace:   kfree+0x117/0x490   ubifs_free_inode+0x4f/0x70 [ubifs]   i_callback+0x30/0x60   rcu_do_batch+0x366/0xac0   __do_softirq+0x133/0x57f  Allocated by task 1506:   kmem_cache_alloc_trace+0x3c2/0x7a0   do_rename+0x9b7/0x1150 [ubifs]   ubifs_rename+0x106/0x1f0 [ubifs]   do_syscall_64+0x35/0x80  Freed by task 1506:   kfree+0x117/0x490   do_rename.cold+0x53/0x8a [ubifs]   ubifs_rename+0x106/0x1f0 [ubifs]   do_syscall_64+0x35/0x80  The buggy address belongs to the object at ffff88810238bed8 which belongs to the cache kmalloc-8 of size 8 ==================================================================  Let ubifs_free_inode() free 'whiteout_ui->data'. BTW, delete unused assignment 'whiteout_ui->data_len = 0', process 'ubifs_evict_inode() -> ubifs_jnl_delete_inode() -> ubifs_jnl_write_inode()' doesn't need it (because 'inc_nlink(whiteout)' won't be excuted by 'goto out_release',  and the nlink of whiteout inode is 0).

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.17.3-1 | [DEBIAN-CVE-2021-47638](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47638.md) | Feb 26, 2025 |
| Linux | linux Debian 13.5 (trixie) | 5.17.3-1 | [DEBIAN-CVE-2021-47638](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47638.md) | Feb 26, 2025 |
| Linux | linux Debian 14 | 5.17.3-1 | [DEBIAN-CVE-2021-47638](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47638.md) | Feb 26, 2025 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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