In the Linux kernel 5.0.21 and 5.3.11, mounting a crafted btrfs filesystem image, performing some operations, and then making a syncfs system call can lead to a use-after-free in try_merge_free_space in fs/btrfs/free-space-cache.c because the pointer to a left data structure can be the same as the pointer to a right data structure.
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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
| Link | Tags |
|---|---|
| https://github.com/bobfuzzer/CVE/tree/master/CVE-2019-19448 | third party advisory exploit |
| https://security.netapp.com/advisory/ntap-20200103-0001/ | third party advisory |
| https://lists.debian.org/debian-lts-announce/2020/09/msg00025.html | third party advisory mailing list |
| https://usn.ubuntu.com/4578-1/ | third party advisory vendor advisory |
| https://lists.debian.org/debian-lts-announce/2020/10/msg00032.html | third party advisory mailing list |
| https://lists.debian.org/debian-lts-announce/2020/10/msg00034.html | third party advisory mailing list |