A use-after-free flaw was found in fs/userfaultfd.c in the Linux kernel before 4.13.6. The issue is related to the handling of fork failure when dealing with event messages. Failure to fork correctly can lead to a situation where a fork event will be removed from an already freed list of events with userfaultfd_ctx_put().
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.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 |
|---|---|
| http://www.securityfocus.com/bid/102516 | third party advisory vdb entry |
| http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=384632e67e0829deb8015ee6ad916b180049d252 | vendor advisory |
| https://bugzilla.redhat.com/show_bug.cgi?id=1523481 | third party advisory issue tracking |
| https://access.redhat.com/errata/RHSA-2018:1062 | third party advisory vendor advisory |
| https://github.com/torvalds/linux/commit/384632e67e0829deb8015ee6ad916b180049d252 | third party advisory |
| https://access.redhat.com/errata/RHSA-2018:0676 | third party advisory vendor advisory |
| https://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.13.6 | vendor advisory |
| https://access.redhat.com/security/cve/CVE-2017-15126 | third party advisory |