CVE-2022-49802 ftrace: Fix null pointer dereference in ftrace_add_mod()

Medium 5.5 Published 1 May 2025 Updated 11 May 2026

A null pointer dereference in the Linux kernel ftrace module can cause a kernel panic and system crash when memory allocation fails.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2022-49802?

CVE-2022-49802 is a medium-severity vulnerability in Linux kernel, published on 1 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

ftrace: Fix null pointer dereference in ftrace_add_mod()

The @ftrace_mod is allocated by kzalloc(), so both the members {prev,next} of @ftrace_mode->list are NULL, it's not a valid state to call list_del(). If kstrdup() for @ftrace_mod->{func|module} fails, it goes to @out_free tag and calls free_ftrace_mod() to destroy @ftrace_mod, then list_del() will write prev->next and next->prev, where null pointer dereference happens.

BUG: kernel NULL pointer dereference, address: 0000000000000008 Oops: 0002 [#1] PREEMPT SMP NOPTI Call Trace: <TASK> ftrace_mod_callback+0x20d/0x220 ? do_filp_open+0xd9/0x140 ftrace_process_regex.isra.51+0xbf/0x130 ftrace_regex_write.isra.52.part.53+0x6e/0x90 vfs_write+0xee/0x3a0 ? __audit_filter_op+0xb1/0x100 ? auditd_test_task+0x38/0x50 ksys_write+0xa5/0xe0 do_syscall_64+0x3a/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd Kernel panic - not syncing: Fatal exception

So call INIT_LIST_HEAD() to initialize the list member to fix this issue.

Weakness: CWE-476

Which versions are affected by CVE-2022-49802?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2022-49802?

Apply the vendor's patch.

Is CVE-2022-49802 being exploited?

There is no known exploitation of CVE-2022-49802 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as DEBIAN-CVE-2022-49802, GHSA-5fcv-vwgv-jrcx, UBUNTU-CVE-2022-49802.