Deadlock Affecting kernel-rt-devel package, versions *

Note: Versions mentioned in the description apply only to the upstream kernel-rt-devel package and not the kernel-rt-devel package as distributed by Centos. See How to fix? for Centos:7 relevant fixed versions and status.

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

aoe: avoid potential deadlock at set_capacity

Move set_capacity() outside of the section procected by (&d->lock). To avoid possible interrupt unsafe locking scenario:

    CPU0                    CPU1
    ----                    ----

[1] lock(&bdev->bd_size_lock); local_irq_disable(); [2] lock(&d->lock); [3] lock(&bdev->bd_size_lock); <Interrupt> [4] lock(&d->lock);

*** DEADLOCK ***

Where 1 hold by zram_add()->set_capacity(). [2]lock(&d->lock) hold by aoeblk_gdalloc(). And aoeblk_gdalloc() is trying to acquire 3 at set_capacity() call. In this situation an attempt to acquire [4]lock(&d->lock) from aoecmd_cfg_rsp() will lead to deadlock.

So the simplest solution is breaking lock dependency 2 -> 3 by moving set_capacity() outside.

• https://access.redhat.com/security/cve/CVE-2024-26775
• https://git.kernel.org/stable/c/19a77b27163820f793b4d022979ffdca8f659b77
• https://git.kernel.org/stable/c/2d623c94fbba3554f4446ba6f3c764994e8b0d26
• https://git.kernel.org/stable/c/673629018ba04906899dcb631beec34d871f709c
• https://git.kernel.org/stable/c/e169bd4fb2b36c4b2bee63c35c740c85daeb2e86