CVE-2021-47638

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).

The following products are affected by CVE-2021-47638 vulnerability.

Here, you will find a curated list of external links that provide in-depth information to CVE-2021-47638.

URL	Resource
https://git.kernel.org/stable/c/14276d38c89a170363e90b6ac0a53c3cf61b87fc
https://git.kernel.org/stable/c/2ad07009c459e56ebdcc089d850d664660fdb742
https://git.kernel.org/stable/c/2b3236ecf96db7af5836e1366ce39ace8ce832fa
https://git.kernel.org/stable/c/40a8f0d5e7b3999f096570edab71c345da812e3e
https://git.kernel.org/stable/c/6d7a158a7363c1f6604aa47ae1a280a5c65123dd
https://git.kernel.org/stable/c/8b3c7be16f3f4dfd6e15ac651484e59d3fa36274
https://git.kernel.org/stable/c/a90e2dbe66d2647ff95a0442ad2e86482d977fd8
https://git.kernel.org/stable/c/b9a937f096e608b3368c1abc920d4d640ba2c94f
https://lore.kernel.org/linux-cve-announce/2025022647-CVE-2021-47638-5ede@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2021-47638
https://www.cve.org/CVERecord?id=CVE-2021-47638