# CVE-2024-35979: raid1: fix use-after-free for original bio in raid1_write_request()

> A use-after-free vulnerability in the Linux kernel RAID1 driver allows local attackers to cause a system crash or potentially execute arbitrary code.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** Yes
- **Published:** 20 May 2024
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2024-35979, DEBIAN-CVE-2024-35979, GHSA-q2cp-mh84-p47v, UBUNTU-CVE-2024-35979

## What is CVE-2024-35979?

CVE-2024-35979 is a high-severity use after free vulnerability in Linux kernel, published on 20 May 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:

raid1: fix use-after-free for original bio in raid1_write_request()

r1_bio->bios[] is used to record new bios that will be issued to
underlying disks, however, in raid1_write_request(), r1_bio->bios[]
will set to the original bio temporarily. Meanwhile, if blocked rdev
is set, free_r1bio() will be called causing that all r1_bio->bios[]
to be freed:

raid1_write_request()
 r1_bio = alloc_r1bio(mddev, bio); -> r1_bio->bios[] is NULL
 for (i = 0;  i < disks; i++) -> for each rdev in conf
  // first rdev is normal
  r1_bio->bios[0] = bio; -> set to original bio
  // second rdev is blocked
  if (test_bit(Blocked, &rdev->flags))
   break

 if (blocked_rdev)
  free_r1bio()
   put_all_bios()
    bio_put(r1_bio->bios[0]) -> original bio is freed

Test scripts:

mdadm -CR /dev/md0 -l1 -n4 /dev/sd[abcd] --assume-clean
fio -filename=/dev/md0 -ioengine=libaio -rw=write -bs=4k -numjobs=1 \
    -iodepth=128 -name=test -direct=1
echo blocked > /sys/block/md0/md/rd2/state

Test result:

BUG bio-264 (Not tainted): Object already free
-----------------------------------------------------------------------------

Allocated in mempool_alloc_slab+0x24/0x50 age=1 cpu=1 pid=869
 kmem_cache_alloc+0x324/0x480
 mempool_alloc_slab+0x24/0x50
 mempool_alloc+0x6e/0x220
 bio_alloc_bioset+0x1af/0x4d0
 blkdev_direct_IO+0x164/0x8a0
 blkdev_write_iter+0x309/0x440
 aio_write+0x139/0x2f0
 io_submit_one+0x5ca/0xb70
 __do_sys_io_submit+0x86/0x270
 __x64_sys_io_submit+0x22/0x30
 do_syscall_64+0xb1/0x210
 entry_SYSCALL_64_after_hwframe+0x6c/0x74
Freed in mempool_free_slab+0x1f/0x30 age=1 cpu=1 pid=869
 kmem_cache_free+0x28c/0x550
 mempool_free_slab+0x1f/0x30
 mempool_free+0x40/0x100
 bio_free+0x59/0x80
 bio_put+0xf0/0x220
 free_r1bio+0x74/0xb0
 raid1_make_request+0xadf/0x1150
 md_handle_request+0xc7/0x3b0
 md_submit_bio+0x76/0x130
 __submit_bio+0xd8/0x1d0
 submit_bio_noacct_nocheck+0x1eb/0x5c0
 submit_bio_noacct+0x169/0xd40
 submit_bio+0xee/0x1d0
 blkdev_direct_IO+0x322/0x8a0
 blkdev_write_iter+0x309/0x440
 aio_write+0x139/0x2f0

Since that bios for underlying disks are not allocated yet, fix this
problem by using mempool_free() directly to free the r1_bio.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2024-35979?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-35979?

Apply the vendor's patch.

## Is CVE-2024-35979 being exploited?

There is no known exploitation of CVE-2024-35979 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-35979 and fix it if it is affected.

What it is: CVE-2024-35979 is a high-severity use after free vulnerability in Linux kernel, published on 20 May 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-35979 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-35979/ (Markdown: https://insights.sbomify.com/CVE-2024-35979/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-35979
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-35979
- OSV: https://osv.dev/vulnerability/CVE-2024-35979

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-35979/
Summaries are generated and may contain mistakes; the official description above is the record.