CVE-2021-47638
"Ubiquitous Filesystem (Ubifs) Double Free Vulnerability"
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).
INFO
Published Date :
Feb. 26, 2025, 6:37 a.m.
Last Modified :
March 18, 2025, 7:08 p.m.
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Remotely Exploitable :
No
Impact Score :
3.6
Exploitability Score :
1.8
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2021-47638.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2021-47638 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2021-47638 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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Initial Analysis by [email protected]
Mar. 18, 2025
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-415 Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 4.20 up to (excluding) 5.4.189 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.11 up to (excluding) 5.15.33 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.17 up to (excluding) 5.17.2 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 4.15 up to (excluding) 4.19.238 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.5 up to (excluding) 5.10.110 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.16 up to (excluding) 5.16.19 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 4.9 up to (excluding) 4.14.276 Added Reference Type kernel.org: https://git.kernel.org/stable/c/14276d38c89a170363e90b6ac0a53c3cf61b87fc Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/2ad07009c459e56ebdcc089d850d664660fdb742 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/2b3236ecf96db7af5836e1366ce39ace8ce832fa Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/40a8f0d5e7b3999f096570edab71c345da812e3e Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/6d7a158a7363c1f6604aa47ae1a280a5c65123dd Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/8b3c7be16f3f4dfd6e15ac651484e59d3fa36274 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/a90e2dbe66d2647ff95a0442ad2e86482d977fd8 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/b9a937f096e608b3368c1abc920d4d640ba2c94f Types: Patch -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Feb. 26, 2025
Action Type Old Value New Value Added 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). Added Reference https://git.kernel.org/stable/c/14276d38c89a170363e90b6ac0a53c3cf61b87fc Added Reference https://git.kernel.org/stable/c/2ad07009c459e56ebdcc089d850d664660fdb742 Added Reference https://git.kernel.org/stable/c/2b3236ecf96db7af5836e1366ce39ace8ce832fa Added Reference https://git.kernel.org/stable/c/40a8f0d5e7b3999f096570edab71c345da812e3e Added Reference https://git.kernel.org/stable/c/6d7a158a7363c1f6604aa47ae1a280a5c65123dd Added Reference https://git.kernel.org/stable/c/8b3c7be16f3f4dfd6e15ac651484e59d3fa36274 Added Reference https://git.kernel.org/stable/c/a90e2dbe66d2647ff95a0442ad2e86482d977fd8 Added Reference https://git.kernel.org/stable/c/b9a937f096e608b3368c1abc920d4d640ba2c94f
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2021-47638 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2021-47638
weaknesses.