CVE-2024-42115 jffs2: Fix potential illegal address access in jffs2_free_inode

High 7.8 Published 30 Jul 2024 Updated 5 Aug 2026

A use-after-free vulnerability in the JFFS2 file system allows attackers to cause a kernel crash via illegal memory access.

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-2024-42115?

CVE-2024-42115 is a high-severity use after free vulnerability in Linux kernel, published on 30 Jul 2024. 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:

jffs2: Fix potential illegal address access in jffs2_free_inode

During the stress testing of the jffs2 file system,the following abnormal printouts were found: [ 2430.649000] Unable to handle kernel paging request at virtual address 0069696969696948 [ 2430.649622] Mem abort info: [ 2430.649829] ESR = 0x96000004 [ 2430.650115] EC = 0x25: DABT (current EL), IL = 32 bits [ 2430.650564] SET = 0, FnV = 0 [ 2430.650795] EA = 0, S1PTW = 0 [ 2430.651032] FSC = 0x04: level 0 translation fault [ 2430.651446] Data abort info: [ 2430.651683] ISV = 0, ISS = 0x00000004 [ 2430.652001] CM = 0, WnR = 0 [ 2430.652558] [0069696969696948] address between user and kernel address ranges [ 2430.653265] Internal error: Oops: 96000004 [#1] PREEMPT SMP [ 2430.654512] CPU: 2 PID: 20919 Comm: cat Not tainted 5.15.25-g512f31242bf6 #33 [ 2430.655008] Hardware name: linux,dummy-virt (DT) [ 2430.655517] pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 2430.656142] pc : kfree+0x78/0x348 [ 2430.656630] lr : jffs2_free_inode+0x24/0x48 [ 2430.657051] sp : ffff800009eebd10 [ 2430.657355] x29: ffff800009eebd10 x28: 0000000000000001 x27: 0000000000000000 [ 2430.658327] x26: ffff000038f09d80 x25: 0080000000000000 x24: ffff800009d38000 [ 2430.658919] x23: 5a5a5a5a5a5a5a5a x22: ffff000038f09d80 x21: ffff8000084f0d14 [ 2430.659434] x20: ffff0000bf9a6ac0 x19: 0169696969696940 x18: 0000000000000000 [ 2430.659969] x17: ffff8000b6506000 x16: ffff800009eec000 x15: 0000000000004000 [ 2430.660637] x14: 0000000000000000 x13: 00000001000820a1 x12: 00000000000d1b19 [ 2430.661345] x11: 0004000800000000 x10: 0000000000000001 x9 : ffff8000084f0d14 [ 2430.662025] x8 : ffff0000bf9a6b40 x7 : ffff0000bf9a6b48 x6 : 0000000003470302 [ 2430.662695] x5 : ffff00002e41dcc0 x4 : ffff0000bf9aa3b0 x3 : 0000000003470342 [ 2430.663486] x2 : 0000000000000000 x1 : ffff8000084f0d14 x0 : fffffc0000000000 [ 2430.664217] Call trace: [ 2430.664528] kfree+0x78/0x348 [ 2430.664855] jffs2_free_inode+0x24/0x48 [ 2430.665233] i_callback+0x24/0x50 [ 2430.665528] rcu_do_batch+0x1ac/0x448 [ 2430.665892] rcu_core+0x28c/0x3c8 [ 2430.666151] rcu_core_si+0x18/0x28 [ 2430.666473] __do_softirq+0x138/0x3cc [ 2430.666781] irq_exit+0xf0/0x110 [ 2430.667065] handle_domain_irq+0x6c/0x98 [ 2430.667447] gic_handle_irq+0xac/0xe8 [ 2430.667739] call_on_irq_stack+0x28/0x54 The parameter passed to kfree was 5a5a5a5a, which corresponds to the target field of the jffs_inode_info structure. It was found that all variables in the jffs_inode_info structure were 5a5a5a5a, except for the first member sem. It is suspected that these variables are not initialized because they were set to 5a5a5a5a during memory testing, which is meant to detect uninitialized memory.The sem variable is initialized in the function jffs2_i_init_once, while other members are initialized in the function jffs2_init_inode_info.

The function jffs2_init_inode_info is called after iget_locked, but in the iget_locked function, the destroy_inode process is triggered, which releases the inode and consequently, the target member of the inode is not initialized.In concurrent high pressure scenarios, iget_locked may enter the destroy_inode branch as described in the code.

Since the destroy_inode functionality of jffs2 only releases the target, the fix method is to set target to NULL in jffs2_i_init_once.

Which versions are affected by CVE-2024-42115?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-42115?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2024-42115 being exploited?

There is no known exploitation of CVE-2024-42115 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2024-42115, DEBIAN-CVE-2024-42115, GHSA-cwhh-7pp8-9f8w, UBUNTU-CVE-2024-42115.