CVE-2022-50344

ext4: fix null-ptr-deref in ext4_write_info

MEDIUM

5.5

CVSS Score

Published: September 16, 2025 at 04:11 PM UTC

Updated: June 17, 2026 at 05:23 AM UTC

1 product affected across 1 vendorLinux Kernel

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Severity

MEDIUM5.5

Exploit prediction

EPSS 0.2%

SSVC

No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: fix null-ptr-deref in ext4_write_info 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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Linux Kernel · Linux

95%

v < 4.9.3313.6 ≤ v < 4.14.2963.6 ≤ v < 4.19.2623.6 ≤ v < 4.9.3313.6 ≤ v < 5.10.1503.6 ≤ v < 5.15.753.6 ≤ v < 5.19.173.6 ≤ v < 5.4.2203.6 ≤ v < 6.0.33.6 ≤ v < 6.14.10 ≤ v < 4.14.2964.15 ≤ v < 4.19.2624.20 ≤ v < 5.4.2205.11 ≤ v < 5.15.755.16 ≤ v < 5.19.175.5 ≤ v < 5.10.1506.0 ≤ v < 6.0.33.6a1177825719ccef3f76ef39bbfd5ebb6087d53c7

Vendor states this is fixed in 3638aa1c7d87c0ca0aef23cf58cae2c48e7daca4 (fixed)

Vendor states this is fixed in 4a657319cfabd6199fd0b7b65bbebf6ded7a11c1 (fixed)

Vendor states this is fixed in 533c60a0b97cee5daab376933f486207e6680fb7 (fixed)

Vendor states this is fixed in 947264e00c46de19a016fd81218118c708fed2f3 (fixed)

Vendor states this is fixed in bb420e8afc854d2a1caaa23a0c129839acfb7888 (fixed)

Vendor states this is fixed in dc451578446afd03c0c21913993c08898a691435 (fixed)

Vendor states this is fixed in f34ab95162763cd7352f46df169296eec28b688d (fixed)

Vendor states this is fixed in f4b5ff0b794aa94afac7269c494550ca2f66511b (fixed)

Vendor states this is fixed in f9c1f248607d5546075d3f731e7607d5571f2b60 (fixed)

Vendor states this is fixed in 3.6 (unaffected)

Vendor states this is fixed in 4.14.296 (unaffected)

Vendor states this is fixed in 4.19.262 (unaffected)

Vendor states this is fixed in 4.9.331 (unaffected)

Vendor states this is fixed in 5.10.150 (unaffected)

Vendor states this is fixed in 5.15.75 (unaffected)

Vendor states this is fixed in 5.19.17 (unaffected)

Vendor states this is fixed in 5.4.220 (unaffected)

Vendor states this is fixed in 6.0.3 (unaffected)

Vendor states this is fixed in 6.1 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references