CVE-2024-50280

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

dm cache: fix flushing uninitialized delayed_work on cache_ctr error

An unexpected WARN_ON from flush_work() may occur when cache creation fails, caused by destroying the uninitialized delayed_work waker in the error path of cache_create(). For example, the warning appears on the superblock checksum error.

Reproduce steps:

dmsetup create cmeta –table 0 8192 linear /dev/sdc 0 dmsetup create cdata –table 0 65536 linear /dev/sdc 8192 dmsetup create corig –table 0 524288 linear /dev/sdc 262144 dd if=/dev/urandom of=/dev/mapper/cmeta bs=4k count=1 oflag=direct dmsetup create cache –table 0 524288 cache /dev/mapper/cmeta /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0

Kernel logs:

(snip) WARNING: CPU: 0 PID: 84 at kernel/workqueue.c:4178 __flush_work+0x5d4/0x890

Fix by pulling out the cancel_delayed_work_sync() from the constructors error path. This patch doesnt affect the use-after-free fix for concurrent dm_resume and dm_destroy (commit 6a459d8edbdb (dm cache: Fix UAF in destroy())) as cache_dtr is not changed.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/135496c208ba26fd68cdef10b64ed7a91ac9a7ff
• https://git.kernel.org/stable/c/40fac0271c7aedf60d81ed8214e80851e5b26312
• https://git.kernel.org/stable/c/5a754d3c771280f2d06bf8ab716d6a0d36ca256e
• https://git.kernel.org/stable/c/8cc12dab635333c4ea28e72d7b947be7d0543c2c
• https://git.kernel.org/stable/c/aee3ecda73ce13af7c3e556383342b57e6bd0718
• https://git.kernel.org/stable/c/d154b333a5667b6c1b213a11a41ad7aaccd10c3d