Description
In the Linux kernel, the following vulnerability has been resolved:

ubifs: authentication: Fix use-after-free in ubifs_tnc_end_commit

After an insertion in TNC, the tree might split and cause a node to
change its `znode->parent`. A further deletion of other nodes in the
tree (which also could free the nodes), the aforementioned node's
`znode->cparent` could still point to a freed node. This
`znode->cparent` may not be updated when getting nodes to commit in
`ubifs_tnc_start_commit()`. This could then trigger a use-after-free
when accessing the `znode->cparent` in `write_index()` in
`ubifs_tnc_end_commit()`.

This can be triggered by running

rm -f /etc/test-file.bin
dd if=/dev/urandom of=/etc/test-file.bin bs=1M count=60 conv=fsync

in a loop, and with `CONFIG_UBIFS_FS_AUTHENTICATION`. KASAN then
reports:

BUG: KASAN: use-after-free in ubifs_tnc_end_commit+0xa5c/0x1950
Write of size 32 at addr ffffff800a3af86c by task ubifs_bgt0_20/153

Call trace:
dump_backtrace+0x0/0x340
show_stack+0x18/0x24
dump_stack_lvl+0x9c/0xbc
print_address_description.constprop.0+0x74/0x2b0
kasan_report+0x1d8/0x1f0
kasan_check_range+0xf8/0x1a0
memcpy+0x84/0xf4
ubifs_tnc_end_commit+0xa5c/0x1950
do_commit+0x4e0/0x1340
ubifs_bg_thread+0x234/0x2e0
kthread+0x36c/0x410
ret_from_fork+0x10/0x20

Allocated by task 401:
kasan_save_stack+0x38/0x70
__kasan_kmalloc+0x8c/0xd0
__kmalloc+0x34c/0x5bc
tnc_insert+0x140/0x16a4
ubifs_tnc_add+0x370/0x52c
ubifs_jnl_write_data+0x5d8/0x870
do_writepage+0x36c/0x510
ubifs_writepage+0x190/0x4dc
__writepage+0x58/0x154
write_cache_pages+0x394/0x830
do_writepages+0x1f0/0x5b0
filemap_fdatawrite_wbc+0x170/0x25c
file_write_and_wait_range+0x140/0x190
ubifs_fsync+0xe8/0x290
vfs_fsync_range+0xc0/0x1e4
do_fsync+0x40/0x90
__arm64_sys_fsync+0x34/0x50
invoke_syscall.constprop.0+0xa8/0x260
do_el0_svc+0xc8/0x1f0
el0_svc+0x34/0x70
el0t_64_sync_handler+0x108/0x114
el0t_64_sync+0x1a4/0x1a8

Freed by task 403:
kasan_save_stack+0x38/0x70
kasan_set_track+0x28/0x40
kasan_set_free_info+0x28/0x4c
__kasan_slab_free+0xd4/0x13c
kfree+0xc4/0x3a0
tnc_delete+0x3f4/0xe40
ubifs_tnc_remove_range+0x368/0x73c
ubifs_tnc_remove_ino+0x29c/0x2e0
ubifs_jnl_delete_inode+0x150/0x260
ubifs_evict_inode+0x1d4/0x2e4
evict+0x1c8/0x450
iput+0x2a0/0x3c4
do_unlinkat+0x2cc/0x490
__arm64_sys_unlinkat+0x90/0x100
invoke_syscall.constprop.0+0xa8/0x260
do_el0_svc+0xc8/0x1f0
el0_svc+0x34/0x70
el0t_64_sync_handler+0x108/0x114
el0t_64_sync+0x1a4/0x1a8

The offending `memcpy()` in `ubifs_copy_hash()` has a use-after-free
when a node becomes root in TNC but still has a `cparent` to an already
freed node. More specifically, consider the following TNC:

zroot
/
/
zp1
/
/
zn

Inserting a new node `zn_new` with a key smaller then `zn` will trigger
a split in `tnc_insert()` if `zp1` is full:

zroot
/ \
/ \
zp1 zp2
/ \
/ \
zn_new zn

`zn->parent` has now been moved to `zp2`, *but* `zn->cparent` still
points to `zp1`.

Now, consider a removal of all the nodes _except_ `zn`. Just when
`tnc_delete()` is about to delete `zroot` and `zp2`:

zroot
\
\
zp2
\
\
zn

`zroot` and `zp2` get freed and the tree collapses:

zn

`zn` now becomes the new `zroot`.

`get_znodes_to_commit()` will now only find `zn`, the new `zroot`, and
`write_index()` will check its `znode->cparent` that wrongly points to
the already freed `zp1`. `ubifs_copy_hash()` thus gets wrongly called
with `znode->cparent->zbranch[znode->iip].hash` that triggers the
use-after-free!

Fix this by explicitly setting `znode->cparent` to `NULL` in
`get_znodes_to_commit()` for the root node. The search for the dirty
nodes
---truncated---
Published: 2024-12-27
Score: 7.8 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4075-1 linux security update
Debian DLA Debian DLA DLA-4076-1 linux-6.1 security update
EUVD EUVD EUVD-2024-51843 In the Linux kernel, the following vulnerability has been resolved: ubifs: authentication: Fix use-after-free in ubifs_tnc_end_commit After an insertion in TNC, the tree might split and cause a node to change its `znode->parent`. A further deletion of other nodes in the tree (which also could free the nodes), the aforementioned node's `znode->cparent` could still point to a freed node. This `znode->cparent` may not be updated when getting nodes to commit in `ubifs_tnc_start_commit()`. This could then trigger a use-after-free when accessing the `znode->cparent` in `write_index()` in `ubifs_tnc_end_commit()`. This can be triggered by running rm -f /etc/test-file.bin dd if=/dev/urandom of=/etc/test-file.bin bs=1M count=60 conv=fsync in a loop, and with `CONFIG_UBIFS_FS_AUTHENTICATION`. KASAN then reports: BUG: KASAN: use-after-free in ubifs_tnc_end_commit+0xa5c/0x1950 Write of size 32 at addr ffffff800a3af86c by task ubifs_bgt0_20/153 Call trace: dump_backtrace+0x0/0x340 show_stack+0x18/0x24 dump_stack_lvl+0x9c/0xbc print_address_description.constprop.0+0x74/0x2b0 kasan_report+0x1d8/0x1f0 kasan_check_range+0xf8/0x1a0 memcpy+0x84/0xf4 ubifs_tnc_end_commit+0xa5c/0x1950 do_commit+0x4e0/0x1340 ubifs_bg_thread+0x234/0x2e0 kthread+0x36c/0x410 ret_from_fork+0x10/0x20 Allocated by task 401: kasan_save_stack+0x38/0x70 __kasan_kmalloc+0x8c/0xd0 __kmalloc+0x34c/0x5bc tnc_insert+0x140/0x16a4 ubifs_tnc_add+0x370/0x52c ubifs_jnl_write_data+0x5d8/0x870 do_writepage+0x36c/0x510 ubifs_writepage+0x190/0x4dc __writepage+0x58/0x154 write_cache_pages+0x394/0x830 do_writepages+0x1f0/0x5b0 filemap_fdatawrite_wbc+0x170/0x25c file_write_and_wait_range+0x140/0x190 ubifs_fsync+0xe8/0x290 vfs_fsync_range+0xc0/0x1e4 do_fsync+0x40/0x90 __arm64_sys_fsync+0x34/0x50 invoke_syscall.constprop.0+0xa8/0x260 do_el0_svc+0xc8/0x1f0 el0_svc+0x34/0x70 el0t_64_sync_handler+0x108/0x114 el0t_64_sync+0x1a4/0x1a8 Freed by task 403: kasan_save_stack+0x38/0x70 kasan_set_track+0x28/0x40 kasan_set_free_info+0x28/0x4c __kasan_slab_free+0xd4/0x13c kfree+0xc4/0x3a0 tnc_delete+0x3f4/0xe40 ubifs_tnc_remove_range+0x368/0x73c ubifs_tnc_remove_ino+0x29c/0x2e0 ubifs_jnl_delete_inode+0x150/0x260 ubifs_evict_inode+0x1d4/0x2e4 evict+0x1c8/0x450 iput+0x2a0/0x3c4 do_unlinkat+0x2cc/0x490 __arm64_sys_unlinkat+0x90/0x100 invoke_syscall.constprop.0+0xa8/0x260 do_el0_svc+0xc8/0x1f0 el0_svc+0x34/0x70 el0t_64_sync_handler+0x108/0x114 el0t_64_sync+0x1a4/0x1a8 The offending `memcpy()` in `ubifs_copy_hash()` has a use-after-free when a node becomes root in TNC but still has a `cparent` to an already freed node. More specifically, consider the following TNC: zroot / / zp1 / / zn Inserting a new node `zn_new` with a key smaller then `zn` will trigger a split in `tnc_insert()` if `zp1` is full: zroot / \ / \ zp1 zp2 / \ / \ zn_new zn `zn->parent` has now been moved to `zp2`, *but* `zn->cparent` still points to `zp1`. Now, consider a removal of all the nodes _except_ `zn`. Just when `tnc_delete()` is about to delete `zroot` and `zp2`: zroot \ \ zp2 \ \ zn `zroot` and `zp2` get freed and the tree collapses: zn `zn` now becomes the new `zroot`. `get_znodes_to_commit()` will now only find `zn`, the new `zroot`, and `write_index()` will check its `znode->cparent` that wrongly points to the already freed `zp1`. `ubifs_copy_hash()` thus gets wrongly called with `znode->cparent->zbranch[znode->iip].hash` that triggers the use-after-free! Fix this by explicitly setting `znode->cparent` to `NULL` in `get_znodes_to_commit()` for the root node. The search for the dirty nodes ---truncated---
Ubuntu USN Ubuntu USN USN-7276-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7277-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7310-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7387-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7387-2 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7387-3 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-7388-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7389-1 Linux kernel (NVIDIA Tegra) vulnerabilities
Ubuntu USN Ubuntu USN USN-7390-1 Linux kernel (Xilinx ZynqMP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7391-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7392-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7392-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7392-3 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7392-4 Linux kernel (AWS FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7393-1 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7401-1 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7407-1 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-7413-1 Linux kernel (IoT) vulnerabilities
Ubuntu USN Ubuntu USN USN-7421-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-7449-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7449-2 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-7450-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7451-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7452-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7453-1 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-7458-1 Linux kernel (IBM) vulnerabilities
Ubuntu USN Ubuntu USN USN-7459-1 Linux kernel (Intel IoTG) vulnerabilities
Ubuntu USN Ubuntu USN USN-7459-2 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7463-1 Linux kernel (IBM) vulnerabilities
Ubuntu USN Ubuntu USN USN-7468-1 Linux kernel (Azure, N-Series) vulnerabilities
Ubuntu USN Ubuntu USN USN-7523-1 Linux kernel (Raspberry Pi Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-7524-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-7539-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-7540-1 Linux kernel (Raspberry Pi) vulnerabilities
History

Mon, 03 Nov 2025 21:30:00 +0000


Wed, 16 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.00027}

epss

{'score': 0.0003}


Tue, 11 Feb 2025 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Tue, 14 Jan 2025 16:45:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Weaknesses CWE-416
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
Metrics cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}


Mon, 30 Dec 2024 01:30:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate


Fri, 27 Dec 2024 14:00:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: ubifs: authentication: Fix use-after-free in ubifs_tnc_end_commit After an insertion in TNC, the tree might split and cause a node to change its `znode->parent`. A further deletion of other nodes in the tree (which also could free the nodes), the aforementioned node's `znode->cparent` could still point to a freed node. This `znode->cparent` may not be updated when getting nodes to commit in `ubifs_tnc_start_commit()`. This could then trigger a use-after-free when accessing the `znode->cparent` in `write_index()` in `ubifs_tnc_end_commit()`. This can be triggered by running rm -f /etc/test-file.bin dd if=/dev/urandom of=/etc/test-file.bin bs=1M count=60 conv=fsync in a loop, and with `CONFIG_UBIFS_FS_AUTHENTICATION`. KASAN then reports: BUG: KASAN: use-after-free in ubifs_tnc_end_commit+0xa5c/0x1950 Write of size 32 at addr ffffff800a3af86c by task ubifs_bgt0_20/153 Call trace: dump_backtrace+0x0/0x340 show_stack+0x18/0x24 dump_stack_lvl+0x9c/0xbc print_address_description.constprop.0+0x74/0x2b0 kasan_report+0x1d8/0x1f0 kasan_check_range+0xf8/0x1a0 memcpy+0x84/0xf4 ubifs_tnc_end_commit+0xa5c/0x1950 do_commit+0x4e0/0x1340 ubifs_bg_thread+0x234/0x2e0 kthread+0x36c/0x410 ret_from_fork+0x10/0x20 Allocated by task 401: kasan_save_stack+0x38/0x70 __kasan_kmalloc+0x8c/0xd0 __kmalloc+0x34c/0x5bc tnc_insert+0x140/0x16a4 ubifs_tnc_add+0x370/0x52c ubifs_jnl_write_data+0x5d8/0x870 do_writepage+0x36c/0x510 ubifs_writepage+0x190/0x4dc __writepage+0x58/0x154 write_cache_pages+0x394/0x830 do_writepages+0x1f0/0x5b0 filemap_fdatawrite_wbc+0x170/0x25c file_write_and_wait_range+0x140/0x190 ubifs_fsync+0xe8/0x290 vfs_fsync_range+0xc0/0x1e4 do_fsync+0x40/0x90 __arm64_sys_fsync+0x34/0x50 invoke_syscall.constprop.0+0xa8/0x260 do_el0_svc+0xc8/0x1f0 el0_svc+0x34/0x70 el0t_64_sync_handler+0x108/0x114 el0t_64_sync+0x1a4/0x1a8 Freed by task 403: kasan_save_stack+0x38/0x70 kasan_set_track+0x28/0x40 kasan_set_free_info+0x28/0x4c __kasan_slab_free+0xd4/0x13c kfree+0xc4/0x3a0 tnc_delete+0x3f4/0xe40 ubifs_tnc_remove_range+0x368/0x73c ubifs_tnc_remove_ino+0x29c/0x2e0 ubifs_jnl_delete_inode+0x150/0x260 ubifs_evict_inode+0x1d4/0x2e4 evict+0x1c8/0x450 iput+0x2a0/0x3c4 do_unlinkat+0x2cc/0x490 __arm64_sys_unlinkat+0x90/0x100 invoke_syscall.constprop.0+0xa8/0x260 do_el0_svc+0xc8/0x1f0 el0_svc+0x34/0x70 el0t_64_sync_handler+0x108/0x114 el0t_64_sync+0x1a4/0x1a8 The offending `memcpy()` in `ubifs_copy_hash()` has a use-after-free when a node becomes root in TNC but still has a `cparent` to an already freed node. More specifically, consider the following TNC: zroot / / zp1 / / zn Inserting a new node `zn_new` with a key smaller then `zn` will trigger a split in `tnc_insert()` if `zp1` is full: zroot / \ / \ zp1 zp2 / \ / \ zn_new zn `zn->parent` has now been moved to `zp2`, *but* `zn->cparent` still points to `zp1`. Now, consider a removal of all the nodes _except_ `zn`. Just when `tnc_delete()` is about to delete `zroot` and `zp2`: zroot \ \ zp2 \ \ zn `zroot` and `zp2` get freed and the tree collapses: zn `zn` now becomes the new `zroot`. `get_znodes_to_commit()` will now only find `zn`, the new `zroot`, and `write_index()` will check its `znode->cparent` that wrongly points to the already freed `zp1`. `ubifs_copy_hash()` thus gets wrongly called with `znode->cparent->zbranch[znode->iip].hash` that triggers the use-after-free! Fix this by explicitly setting `znode->cparent` to `NULL` in `get_znodes_to_commit()` for the root node. The search for the dirty nodes ---truncated---
Title ubifs: authentication: Fix use-after-free in ubifs_tnc_end_commit
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-05-11T20:52:12.907Z

Reserved: 2024-11-19T17:17:25.006Z

Link: CVE-2024-53171

cve-icon Vulnrichment

Updated: 2025-02-11T15:43:47.043Z

cve-icon NVD

Status : Modified

Published: 2024-12-27T14:15:24.300

Modified: 2025-11-03T21:17:36.410

Link: CVE-2024-53171

cve-icon Redhat

Severity : Moderate

Publid Date: 2024-12-27T00:00:00Z

Links: CVE-2024-53171 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses