CVE-2026-46121

01/Description

In the Linux kernel, the following vulnerability has been resolved: mm/damon/sysfs-schemes: protect memcg_path kfree() with damon_sysfs_lock Patch series "mm/damon/sysfs-schemes: fix use-after-free for [memcg_]path". Reads of 'memcg_path' and 'path' files in DAMON sysfs interface could race with their writes, results in use-after-free. Fix those. This patch (of 2): damon_sysfs_scheme_filter->mmecg_path can be read and written by users, via DAMON sysfs memcg_path file. It can also be indirectly read, for the parameters {on,off}line committing to DAMON. The reads for parameters committing are protected by damon_sysfs_lock to avoid the sysfs files being destroyed while any of the parameters are being read. But the user-driven direct reads and writes are not protected by any lock, while the write is deallocating the memcg_path-pointing buffer. As a result, the readers could read the already freed buffer (user-after-free). Note that the user-reads don't race when the same open file is used by the writer, due to kernfs's open file locking. Nonetheless, doing the reads and writes with separate open files would be common. Fix it by protecting both the user-direct reads and writes with damon_sysfs_lock.

02/Affected products

linux: linux kernel

03/References5

• git.kernel.org/stable/c/1e68eb96e8beb1abefd12dd22c5637795d8a877e Patch
• git.kernel.org/stable/c/b1e9f2d5870776347edef927f9bb3ea19b8e3abb Patch
• git.kernel.org/stable/c/baecc45ad60e621ef14d6c1e7f41ef36bbfdf910 Patch
• git.kernel.org/stable/c/c88802d0e8edd14b6cd2daf3000f99adbc4c85c5 Patch
• git.kernel.org/stable/c/eafd6f5372d29b0dd213799b92c2c9c7ad31d7da Patch