|
Message-ID: <1973d16e-bb3e-c5b2-74e0-cc2faf9db2bd@redhat.com> Date: Mon, 8 Aug 2022 09:18:27 +0200 From: David Hildenbrand <david@...hat.com> To: oss-security@...ts.openwall.com Subject: CVE-2022-2590: Linux kernel: Modifying shmem/tmpfs files without write permissions Hi, I found a security issue (CVE-2022-2590) in the Linux kernel similar to Dirty COW (CVE-2016-5195), however, restricted to shared memory (shmem / tmpfs). I notified distributions one week ago and the embargo ended today. An unprivileged user can modify file content of a shmem (tmpfs) file, even if that user does not have write permissions to the file. The file could be an executable. The introducing upstream commit ID is: 9ae0f87d009c ("mm/shmem: unconditionally set pte dirty in mfill_atomic_install_pte") Linux >= v5.16 is affected on x86-64 and aarch64 if the kernel is compiled with CONFIG_USERFAULTFD=y. For Linux < v5.19 it's sufficient to revert the problematic commit, which is possible with minor contextual conflicts. For Linux >= v5.19 I'll send a proposal fix today. I have a working reproducer that I will post as reply to this mail in one week (August 15). -- Thanks, David / dhildenb
Powered by blists - more mailing lists
Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.