CVE-2019-19807

In the Linux kernel before 5.3.11, sound/core/timer.c has a use-after-free caused by erroneous code refactoring, aka CID-e7af6307a8a5. This is related to snd_timer_open and snd_timer_close_locked. The timeri variable was originally intended to be for a newly created timer instance, but was used for a different purpose after refactoring.

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 Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.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://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.3.11
• https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=e7af6307a8a54f0b873960b32b6a644f2d0fbd97
• https://github.com/torvalds/linux/commit/e7af6307a8a54f0b873960b32b6a644f2d0fbd97
• https://security.netapp.com/advisory/ntap-20200103-0001/
• https://usn.ubuntu.com/4225-1/
• https://usn.ubuntu.com/4227-1/
• https://usn.ubuntu.com/4227-2/
• https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.3.11
• https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=e7af6307a8a54f0b873960b32b6a644f2d0fbd97
• https://github.com/torvalds/linux/commit/e7af6307a8a54f0b873960b32b6a644f2d0fbd97
• https://security.netapp.com/advisory/ntap-20200103-0001/
• https://usn.ubuntu.com/4225-1/
• https://usn.ubuntu.com/4227-1/
• https://usn.ubuntu.com/4227-2/