CVE-2022-50344 - ext4: fix null-ptr-deref in ext4_write_info

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MEDIUM

ext4: fix null-ptr-deref in ext4_write_info

Published Sep 16, 2025

5.5

MEDIUM

CVSS 3.1

EPSS 0.16%

Description

I caught a null-ptr-deref bug as follows: ================================================================== KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f] CPU: 1 PID: 1589 Comm: umount Not tainted 5.10.0-02219-dirty #339 RIP: 0010:ext4_write_info+0x53/0x1b0 [...] Call Trace: dquot_writeback_dquots+0x341/0x9a0 ext4_sync_fs+0x19e/0x800 __sync_filesystem+0x83/0x100 sync_filesystem+0x89/0xf0 generic_shutdown_super+0x79/0x3e0 kill_block_super+0xa1/0x110 deactivate_locked_super+0xac/0x130 deactivate_super+0xb6/0xd0 cleanup_mnt+0x289/0x400 __cleanup_mnt+0x16/0x20 task_work_run+0x11c/0x1c0 exit_to_user_mode_prepare+0x203/0x210 syscall_exit_to_user_mode+0x5b/0x3a0 do_syscall_64+0x59/0x70 entry_SYSCALL_64_after_hwframe+0x44/0xa9 ==================================================================

Above issue may happen as follows: ------------------------------------- exit_to_user_mode_prepare task_work_run __cleanup_mnt cleanup_mnt deactivate_super deactivate_locked_super kill_block_super generic_shutdown_super shrink_dcache_for_umount dentry = sb->s_root sb->s_root = NULL <--- Here set NULL sync_filesystem __sync_filesystem sb->s_op->sync_fs > ext4_sync_fs dquot_writeback_dquots sb->dq_op->write_info > ext4_write_info ext4_journal_start(d_inode(sb->s_root), EXT4_HT_QUOTA, 2) d_inode(sb->s_root) s_root->d_inode <--- Null pointer dereference

To solve this problem, we use ext4_journal_start_sb directly to avoid s_root being used.

Affected products

Vendor Linux Product Linux Default
unaffected
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
Vendor Linux Product Linux Default
affected
- Version
  3.6
  Status
  affected
  Constraints
  -
- Version
  0
  Status
  unaffected
  Constraints
  <3.6
- Version
  4.14.296
  Status
  unaffected
  Constraints
  <=4.14.*
- Version
  4.19.262
  Status
  unaffected
  Constraints
  <=4.19.*
- Version
  4.9.331
  Status
  unaffected
  Constraints
  <=4.9.*
- Version
  5.10.150
  Status
  unaffected
  Constraints
  <=5.10.*
- Version
  5.15.75
  Status
  unaffected
  Constraints
  <=5.15.*
- Version
  5.19.17
  Status
  unaffected
  Constraints
  <=5.19.*
- Version
  5.4.220
  Status
  unaffected
  Constraints
  <=5.4.*
- Version
  6.0.3
  Status
  unaffected
  Constraints
  <=6.0.*
- Version
  6.1
  Status
  unaffected
  Constraints
  <=*

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

Linux

unaffected

Version	Status	Constraints
	affected
	affected
	affected
	affected
	affected
	affected
	affected
	affected
	affected

Linux

affected

Version	Status	Constraints
3.6	affected	-
0	unaffected	<3.6
4.14.296	unaffected	<=4.14.*
4.19.262	unaffected	<=4.19.*
4.9.331	unaffected	<=4.9.*
5.10.150	unaffected	<=5.10.*
5.15.75	unaffected	<=5.15.*
5.19.17	unaffected	<=5.19.*
5.4.220	unaffected	<=5.4.*
6.0.3	unaffected	<=6.0.*
6.1	unaffected	<=*

Red Hat Enterprise Linux 8

kernel-0:4.18.0-553.el8_10

Fixed · RHSA-2024:3138
Red Hat Enterprise Linux 9

kernel-0:5.14.0-284.11.1.el9_2

Fixed · RHSA-2023:2458
Red Hat Enterprise Linux 9

kernel-0:5.14.0-284.11.1.el9_2

Fixed · RHSA-2023:2458
Red Hat Enterprise Linux 10

kernel

Not affected
Red Hat Enterprise Linux 6

kernel

Out of support scope
Red Hat Enterprise Linux 7

kernel

Fix deferred
Red Hat Enterprise Linux 7

kernel-rt

Fix deferred
Red Hat Enterprise Linux 8

kernel-rt

Fix deferred
Red Hat Enterprise Linux 9

kernel-rt

Fix deferred

Product	Package	State	Advisory
Red Hat Enterprise Linux 8	kernel-0:4.18.0-553.el8_10	Fixed	RHSA-2024:3138
Red Hat Enterprise Linux 9	kernel-0:5.14.0-284.11.1.el9_2	Fixed	RHSA-2023:2458
Red Hat Enterprise Linux 9	kernel-0:5.14.0-284.11.1.el9_2	Fixed	RHSA-2023:2458
Red Hat Enterprise Linux 10	kernel	Not affected	n/a
Red Hat Enterprise Linux 6	kernel	Out of support scope	n/a
Red Hat Enterprise Linux 7	kernel	Fix deferred	n/a
Red Hat Enterprise Linux 7	kernel-rt	Fix deferred	n/a
Red Hat Enterprise Linux 8	kernel-rt	Fix deferred	n/a
Red Hat Enterprise Linux 9	kernel-rt	Fix deferred	n/a

Remediation

No remediation recorded yet.

Weaknesses (1)

CWE-476

NULL Pointer Dereference

References (15)

Link	Providers	Tags
https://access.redhat.com/security/cve/CVE-2022-50344		Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2395860		Issue Tracking
https://euvd.enisa.europa.eu/vulnerability/EUVD-2022-55618		Advisory
https://git.kernel.org/stable/c/3638aa1c7d87c0ca0aef23cf58cae2c48e7daca4		Patch
https://git.kernel.org/stable/c/4a657319cfabd6199fd0b7b65bbebf6ded7a11c1		Patch
https://git.kernel.org/stable/c/533c60a0b97cee5daab376933f486207e6680fb7		Patch
https://git.kernel.org/stable/c/947264e00c46de19a016fd81218118c708fed2f3		Patch
https://git.kernel.org/stable/c/bb420e8afc854d2a1caaa23a0c129839acfb7888		Patch
https://git.kernel.org/stable/c/dc451578446afd03c0c21913993c08898a691435		Patch
https://git.kernel.org/stable/c/f34ab95162763cd7352f46df169296eec28b688d		Patch
https://git.kernel.org/stable/c/f4b5ff0b794aa94afac7269c494550ca2f66511b		Patch
https://git.kernel.org/stable/c/f9c1f248607d5546075d3f731e7607d5571f2b60		Patch
https://lore.kernel.org/linux-cve-announce/2025091639-CVE-2022-50344-8893@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2022-50344
https://www.cve.org/CVERecord?id=CVE-2022-50344