CVE-2024-26755 md: Don't suspend the array for interrupted reshape

What is CVE-2024-26755?

CVE-2024-26755 is a medium-severity denial of service vulnerability in Linux kernel, published on 3 Apr 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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

md: Don't suspend the array for interrupted reshape

md_start_sync() will suspend the array if there are spares that can be added or removed from conf, however, if reshape is still in progress, this won't happen at all or data will be corrupted(remove_and_add_spares won't be called from md_choose_sync_action for reshape), hence there is no need to suspend the array if reshape is not done yet.

Meanwhile, there is a potential deadlock for raid456:

1) reshape is interrupted;

2) set one of the disk WantReplacement, and add a new disk to the array, however, recovery won't start until the reshape is finished;

3) then issue an IO across reshpae position, this IO will wait for reshape to make progress;

4) continue to reshape, then md_start_sync() found there is a spare disk that can be added to conf, mddev_suspend() is called;

Step 4 and step 3 is waiting for each other, deadlock triggered. Noted this problem is found by code review, and it's not reporduced yet.

Fix this porblem by don't suspend the array for interrupted reshape, this is safe because conf won't be changed until reshape is done.

Weakness: CWE-129

Which versions are affected by CVE-2024-26755?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-26755?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2024-26755 being exploited?

There is no known exploitation of CVE-2024-26755 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2024-26755, DEBIAN-CVE-2024-26755, GHSA-f2c7-w7wj-2qjw, UBUNTU-CVE-2024-26755.